linux/fs/xfs/xfs_log_priv.h

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
* All Rights Reserved.
*/
#ifndef __XFS_LOG_PRIV_H__
#define __XFS_LOG_PRIV_H__
struct xfs_buf;
struct xlog;
struct xlog_ticket;
struct xfs_mount;
struct xfs_log_callback;
/*
* Flags for log structure
*/
#define XLOG_ACTIVE_RECOVERY 0x2 /* in the middle of recovery */
#define XLOG_RECOVERY_NEEDED 0x4 /* log was recovered */
#define XLOG_IO_ERROR 0x8 /* log hit an I/O error, and being
shutdown */
#define XLOG_TAIL_WARN 0x10 /* log tail verify warning issued */
/*
* get client id from packed copy.
*
* this hack is here because the xlog_pack code copies four bytes
* of xlog_op_header containing the fields oh_clientid, oh_flags
* and oh_res2 into the packed copy.
*
* later on this four byte chunk is treated as an int and the
* client id is pulled out.
*
* this has endian issues, of course.
*/
static inline uint xlog_get_client_id(__be32 i)
{
return be32_to_cpu(i) >> 24;
}
/*
* In core log state
*/
#define XLOG_STATE_ACTIVE 0x0001 /* Current IC log being written to */
#define XLOG_STATE_WANT_SYNC 0x0002 /* Want to sync this iclog; no more writes */
#define XLOG_STATE_SYNCING 0x0004 /* This IC log is syncing */
#define XLOG_STATE_DONE_SYNC 0x0008 /* Done syncing to disk */
#define XLOG_STATE_DO_CALLBACK \
0x0010 /* Process callback functions */
#define XLOG_STATE_CALLBACK 0x0020 /* Callback functions now */
#define XLOG_STATE_DIRTY 0x0040 /* Dirty IC log, not ready for ACTIVE status*/
#define XLOG_STATE_IOERROR 0x0080 /* IO error happened in sync'ing log */
#define XLOG_STATE_IOABORT 0x0100 /* force abort on I/O completion (debug) */
#define XLOG_STATE_ALL 0x7FFF /* All possible valid flags */
#define XLOG_STATE_NOTUSED 0x8000 /* This IC log not being used */
/*
* Flags to log ticket
*/
#define XLOG_TIC_INITED 0x1 /* has been initialized */
#define XLOG_TIC_PERM_RESERV 0x2 /* permanent reservation */
xfs: event tracing support Convert the old xfs tracing support that could only be used with the out of tree kdb and xfsidbg patches to use the generic event tracer. To use it make sure CONFIG_EVENT_TRACING is enabled and then enable all xfs trace channels by: echo 1 > /sys/kernel/debug/tracing/events/xfs/enable or alternatively enable single events by just doing the same in one event subdirectory, e.g. echo 1 > /sys/kernel/debug/tracing/events/xfs/xfs_ihold/enable or set more complex filters, etc. In Documentation/trace/events.txt all this is desctribed in more detail. To reads the events do a cat /sys/kernel/debug/tracing/trace Compared to the last posting this patch converts the tracing mostly to the one tracepoint per callsite model that other users of the new tracing facility also employ. This allows a very fine-grained control of the tracing, a cleaner output of the traces and also enables the perf tool to use each tracepoint as a virtual performance counter, allowing us to e.g. count how often certain workloads git various spots in XFS. Take a look at http://lwn.net/Articles/346470/ for some examples. Also the btree tracing isn't included at all yet, as it will require additional core tracing features not in mainline yet, I plan to deliver it later. And the really nice thing about this patch is that it actually removes many lines of code while adding this nice functionality: fs/xfs/Makefile | 8 fs/xfs/linux-2.6/xfs_acl.c | 1 fs/xfs/linux-2.6/xfs_aops.c | 52 - fs/xfs/linux-2.6/xfs_aops.h | 2 fs/xfs/linux-2.6/xfs_buf.c | 117 +-- fs/xfs/linux-2.6/xfs_buf.h | 33 fs/xfs/linux-2.6/xfs_fs_subr.c | 3 fs/xfs/linux-2.6/xfs_ioctl.c | 1 fs/xfs/linux-2.6/xfs_ioctl32.c | 1 fs/xfs/linux-2.6/xfs_iops.c | 1 fs/xfs/linux-2.6/xfs_linux.h | 1 fs/xfs/linux-2.6/xfs_lrw.c | 87 -- fs/xfs/linux-2.6/xfs_lrw.h | 45 - fs/xfs/linux-2.6/xfs_super.c | 104 --- fs/xfs/linux-2.6/xfs_super.h | 7 fs/xfs/linux-2.6/xfs_sync.c | 1 fs/xfs/linux-2.6/xfs_trace.c | 75 ++ fs/xfs/linux-2.6/xfs_trace.h | 1369 +++++++++++++++++++++++++++++++++++++++++ fs/xfs/linux-2.6/xfs_vnode.h | 4 fs/xfs/quota/xfs_dquot.c | 110 --- fs/xfs/quota/xfs_dquot.h | 21 fs/xfs/quota/xfs_qm.c | 40 - fs/xfs/quota/xfs_qm_syscalls.c | 4 fs/xfs/support/ktrace.c | 323 --------- fs/xfs/support/ktrace.h | 85 -- fs/xfs/xfs.h | 16 fs/xfs/xfs_ag.h | 14 fs/xfs/xfs_alloc.c | 230 +----- fs/xfs/xfs_alloc.h | 27 fs/xfs/xfs_alloc_btree.c | 1 fs/xfs/xfs_attr.c | 107 --- fs/xfs/xfs_attr.h | 10 fs/xfs/xfs_attr_leaf.c | 14 fs/xfs/xfs_attr_sf.h | 40 - fs/xfs/xfs_bmap.c | 507 +++------------ fs/xfs/xfs_bmap.h | 49 - fs/xfs/xfs_bmap_btree.c | 6 fs/xfs/xfs_btree.c | 5 fs/xfs/xfs_btree_trace.h | 17 fs/xfs/xfs_buf_item.c | 87 -- fs/xfs/xfs_buf_item.h | 20 fs/xfs/xfs_da_btree.c | 3 fs/xfs/xfs_da_btree.h | 7 fs/xfs/xfs_dfrag.c | 2 fs/xfs/xfs_dir2.c | 8 fs/xfs/xfs_dir2_block.c | 20 fs/xfs/xfs_dir2_leaf.c | 21 fs/xfs/xfs_dir2_node.c | 27 fs/xfs/xfs_dir2_sf.c | 26 fs/xfs/xfs_dir2_trace.c | 216 ------ fs/xfs/xfs_dir2_trace.h | 72 -- fs/xfs/xfs_filestream.c | 8 fs/xfs/xfs_fsops.c | 2 fs/xfs/xfs_iget.c | 111 --- fs/xfs/xfs_inode.c | 67 -- fs/xfs/xfs_inode.h | 76 -- fs/xfs/xfs_inode_item.c | 5 fs/xfs/xfs_iomap.c | 85 -- fs/xfs/xfs_iomap.h | 8 fs/xfs/xfs_log.c | 181 +---- fs/xfs/xfs_log_priv.h | 20 fs/xfs/xfs_log_recover.c | 1 fs/xfs/xfs_mount.c | 2 fs/xfs/xfs_quota.h | 8 fs/xfs/xfs_rename.c | 1 fs/xfs/xfs_rtalloc.c | 1 fs/xfs/xfs_rw.c | 3 fs/xfs/xfs_trans.h | 47 + fs/xfs/xfs_trans_buf.c | 62 - fs/xfs/xfs_vnodeops.c | 8 70 files changed, 2151 insertions(+), 2592 deletions(-) Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2009-12-14 23:14:59 +00:00
#define XLOG_TIC_FLAGS \
{ XLOG_TIC_INITED, "XLOG_TIC_INITED" }, \
{ XLOG_TIC_PERM_RESERV, "XLOG_TIC_PERM_RESERV" }
xfs: event tracing support Convert the old xfs tracing support that could only be used with the out of tree kdb and xfsidbg patches to use the generic event tracer. To use it make sure CONFIG_EVENT_TRACING is enabled and then enable all xfs trace channels by: echo 1 > /sys/kernel/debug/tracing/events/xfs/enable or alternatively enable single events by just doing the same in one event subdirectory, e.g. echo 1 > /sys/kernel/debug/tracing/events/xfs/xfs_ihold/enable or set more complex filters, etc. In Documentation/trace/events.txt all this is desctribed in more detail. To reads the events do a cat /sys/kernel/debug/tracing/trace Compared to the last posting this patch converts the tracing mostly to the one tracepoint per callsite model that other users of the new tracing facility also employ. This allows a very fine-grained control of the tracing, a cleaner output of the traces and also enables the perf tool to use each tracepoint as a virtual performance counter, allowing us to e.g. count how often certain workloads git various spots in XFS. Take a look at http://lwn.net/Articles/346470/ for some examples. Also the btree tracing isn't included at all yet, as it will require additional core tracing features not in mainline yet, I plan to deliver it later. And the really nice thing about this patch is that it actually removes many lines of code while adding this nice functionality: fs/xfs/Makefile | 8 fs/xfs/linux-2.6/xfs_acl.c | 1 fs/xfs/linux-2.6/xfs_aops.c | 52 - fs/xfs/linux-2.6/xfs_aops.h | 2 fs/xfs/linux-2.6/xfs_buf.c | 117 +-- fs/xfs/linux-2.6/xfs_buf.h | 33 fs/xfs/linux-2.6/xfs_fs_subr.c | 3 fs/xfs/linux-2.6/xfs_ioctl.c | 1 fs/xfs/linux-2.6/xfs_ioctl32.c | 1 fs/xfs/linux-2.6/xfs_iops.c | 1 fs/xfs/linux-2.6/xfs_linux.h | 1 fs/xfs/linux-2.6/xfs_lrw.c | 87 -- fs/xfs/linux-2.6/xfs_lrw.h | 45 - fs/xfs/linux-2.6/xfs_super.c | 104 --- fs/xfs/linux-2.6/xfs_super.h | 7 fs/xfs/linux-2.6/xfs_sync.c | 1 fs/xfs/linux-2.6/xfs_trace.c | 75 ++ fs/xfs/linux-2.6/xfs_trace.h | 1369 +++++++++++++++++++++++++++++++++++++++++ fs/xfs/linux-2.6/xfs_vnode.h | 4 fs/xfs/quota/xfs_dquot.c | 110 --- fs/xfs/quota/xfs_dquot.h | 21 fs/xfs/quota/xfs_qm.c | 40 - fs/xfs/quota/xfs_qm_syscalls.c | 4 fs/xfs/support/ktrace.c | 323 --------- fs/xfs/support/ktrace.h | 85 -- fs/xfs/xfs.h | 16 fs/xfs/xfs_ag.h | 14 fs/xfs/xfs_alloc.c | 230 +----- fs/xfs/xfs_alloc.h | 27 fs/xfs/xfs_alloc_btree.c | 1 fs/xfs/xfs_attr.c | 107 --- fs/xfs/xfs_attr.h | 10 fs/xfs/xfs_attr_leaf.c | 14 fs/xfs/xfs_attr_sf.h | 40 - fs/xfs/xfs_bmap.c | 507 +++------------ fs/xfs/xfs_bmap.h | 49 - fs/xfs/xfs_bmap_btree.c | 6 fs/xfs/xfs_btree.c | 5 fs/xfs/xfs_btree_trace.h | 17 fs/xfs/xfs_buf_item.c | 87 -- fs/xfs/xfs_buf_item.h | 20 fs/xfs/xfs_da_btree.c | 3 fs/xfs/xfs_da_btree.h | 7 fs/xfs/xfs_dfrag.c | 2 fs/xfs/xfs_dir2.c | 8 fs/xfs/xfs_dir2_block.c | 20 fs/xfs/xfs_dir2_leaf.c | 21 fs/xfs/xfs_dir2_node.c | 27 fs/xfs/xfs_dir2_sf.c | 26 fs/xfs/xfs_dir2_trace.c | 216 ------ fs/xfs/xfs_dir2_trace.h | 72 -- fs/xfs/xfs_filestream.c | 8 fs/xfs/xfs_fsops.c | 2 fs/xfs/xfs_iget.c | 111 --- fs/xfs/xfs_inode.c | 67 -- fs/xfs/xfs_inode.h | 76 -- fs/xfs/xfs_inode_item.c | 5 fs/xfs/xfs_iomap.c | 85 -- fs/xfs/xfs_iomap.h | 8 fs/xfs/xfs_log.c | 181 +---- fs/xfs/xfs_log_priv.h | 20 fs/xfs/xfs_log_recover.c | 1 fs/xfs/xfs_mount.c | 2 fs/xfs/xfs_quota.h | 8 fs/xfs/xfs_rename.c | 1 fs/xfs/xfs_rtalloc.c | 1 fs/xfs/xfs_rw.c | 3 fs/xfs/xfs_trans.h | 47 + fs/xfs/xfs_trans_buf.c | 62 - fs/xfs/xfs_vnodeops.c | 8 70 files changed, 2151 insertions(+), 2592 deletions(-) Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2009-12-14 23:14:59 +00:00
/*
* Below are states for covering allocation transactions.
* By covering, we mean changing the h_tail_lsn in the last on-disk
* log write such that no allocation transactions will be re-done during
* recovery after a system crash. Recovery starts at the last on-disk
* log write.
*
* These states are used to insert dummy log entries to cover
* space allocation transactions which can undo non-transactional changes
* after a crash. Writes to a file with space
* already allocated do not result in any transactions. Allocations
* might include space beyond the EOF. So if we just push the EOF a
* little, the last transaction for the file could contain the wrong
* size. If there is no file system activity, after an allocation
* transaction, and the system crashes, the allocation transaction
* will get replayed and the file will be truncated. This could
* be hours/days/... after the allocation occurred.
*
* The fix for this is to do two dummy transactions when the
* system is idle. We need two dummy transaction because the h_tail_lsn
* in the log record header needs to point beyond the last possible
* non-dummy transaction. The first dummy changes the h_tail_lsn to
* the first transaction before the dummy. The second dummy causes
* h_tail_lsn to point to the first dummy. Recovery starts at h_tail_lsn.
*
* These dummy transactions get committed when everything
* is idle (after there has been some activity).
*
* There are 5 states used to control this.
*
* IDLE -- no logging has been done on the file system or
* we are done covering previous transactions.
* NEED -- logging has occurred and we need a dummy transaction
* when the log becomes idle.
* DONE -- we were in the NEED state and have committed a dummy
* transaction.
* NEED2 -- we detected that a dummy transaction has gone to the
* on disk log with no other transactions.
* DONE2 -- we committed a dummy transaction when in the NEED2 state.
*
* There are two places where we switch states:
*
* 1.) In xfs_sync, when we detect an idle log and are in NEED or NEED2.
* We commit the dummy transaction and switch to DONE or DONE2,
* respectively. In all other states, we don't do anything.
*
* 2.) When we finish writing the on-disk log (xlog_state_clean_log).
*
* No matter what state we are in, if this isn't the dummy
* transaction going out, the next state is NEED.
* So, if we aren't in the DONE or DONE2 states, the next state
* is NEED. We can't be finishing a write of the dummy record
* unless it was committed and the state switched to DONE or DONE2.
*
* If we are in the DONE state and this was a write of the
* dummy transaction, we move to NEED2.
*
* If we are in the DONE2 state and this was a write of the
* dummy transaction, we move to IDLE.
*
*
* Writing only one dummy transaction can get appended to
* one file space allocation. When this happens, the log recovery
* code replays the space allocation and a file could be truncated.
* This is why we have the NEED2 and DONE2 states before going idle.
*/
#define XLOG_STATE_COVER_IDLE 0
#define XLOG_STATE_COVER_NEED 1
#define XLOG_STATE_COVER_DONE 2
#define XLOG_STATE_COVER_NEED2 3
#define XLOG_STATE_COVER_DONE2 4
#define XLOG_COVER_OPS 5
/* Ticket reservation region accounting */
#define XLOG_TIC_LEN_MAX 15
/*
* Reservation region
* As would be stored in xfs_log_iovec but without the i_addr which
* we don't care about.
*/
typedef struct xlog_res {
uint r_len; /* region length :4 */
uint r_type; /* region's transaction type :4 */
} xlog_res_t;
typedef struct xlog_ticket {
struct list_head t_queue; /* reserve/write queue */
struct task_struct *t_task; /* task that owns this ticket */
xlog_tid_t t_tid; /* transaction identifier : 4 */
atomic_t t_ref; /* ticket reference count : 4 */
int t_curr_res; /* current reservation in bytes : 4 */
int t_unit_res; /* unit reservation in bytes : 4 */
char t_ocnt; /* original count : 1 */
char t_cnt; /* current count : 1 */
char t_clientid; /* who does this belong to; : 1 */
char t_flags; /* properties of reservation : 1 */
/* reservation array fields */
uint t_res_num; /* num in array : 4 */
uint t_res_num_ophdrs; /* num op hdrs : 4 */
uint t_res_arr_sum; /* array sum : 4 */
uint t_res_o_flow; /* sum overflow : 4 */
xlog_res_t t_res_arr[XLOG_TIC_LEN_MAX]; /* array of res : 8 * 15 */
} xlog_ticket_t;
/*
* - A log record header is 512 bytes. There is plenty of room to grow the
* xlog_rec_header_t into the reserved space.
* - ic_data follows, so a write to disk can start at the beginning of
* the iclog.
* - ic_forcewait is used to implement synchronous forcing of the iclog to disk.
* - ic_next is the pointer to the next iclog in the ring.
* - ic_bp is a pointer to the buffer used to write this incore log to disk.
* - ic_log is a pointer back to the global log structure.
* - ic_callback is a linked list of callback function/argument pairs to be
* called after an iclog finishes writing.
* - ic_size is the full size of the header plus data.
* - ic_offset is the current number of bytes written to in this iclog.
* - ic_refcnt is bumped when someone is writing to the log.
* - ic_state is the state of the iclog.
*
* Because of cacheline contention on large machines, we need to separate
* various resources onto different cachelines. To start with, make the
* structure cacheline aligned. The following fields can be contended on
* by independent processes:
*
* - ic_callback_*
* - ic_refcnt
* - fields protected by the global l_icloglock
*
* so we need to ensure that these fields are located in separate cachelines.
* We'll put all the read-only and l_icloglock fields in the first cacheline,
* and move everything else out to subsequent cachelines.
*/
typedef struct xlog_in_core {
wait_queue_head_t ic_force_wait;
wait_queue_head_t ic_write_wait;
struct xlog_in_core *ic_next;
struct xlog_in_core *ic_prev;
struct xfs_buf *ic_bp;
struct xlog *ic_log;
int ic_size;
int ic_offset;
int ic_bwritecnt;
unsigned short ic_state;
char *ic_datap; /* pointer to iclog data */
/* Callback structures need their own cacheline */
spinlock_t ic_callback_lock ____cacheline_aligned_in_smp;
struct xfs_log_callback *ic_callback;
struct xfs_log_callback **ic_callback_tail;
/* reference counts need their own cacheline */
atomic_t ic_refcnt ____cacheline_aligned_in_smp;
xlog_in_core_2_t *ic_data;
#define ic_header ic_data->hic_header
} xlog_in_core_t;
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
/*
* The CIL context is used to aggregate per-transaction details as well be
* passed to the iclog for checkpoint post-commit processing. After being
* passed to the iclog, another context needs to be allocated for tracking the
* next set of transactions to be aggregated into a checkpoint.
*/
struct xfs_cil;
struct xfs_cil_ctx {
struct xfs_cil *cil;
xfs_lsn_t sequence; /* chkpt sequence # */
xfs_lsn_t start_lsn; /* first LSN of chkpt commit */
xfs_lsn_t commit_lsn; /* chkpt commit record lsn */
struct xlog_ticket *ticket; /* chkpt ticket */
int nvecs; /* number of regions */
int space_used; /* aggregate size of regions */
struct list_head busy_extents; /* busy extents in chkpt */
struct xfs_log_vec *lv_chain; /* logvecs being pushed */
struct xfs_log_callback log_cb; /* completion callback hook. */
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
struct list_head committing; /* ctx committing list */
struct work_struct discard_endio_work;
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
};
/*
* Committed Item List structure
*
* This structure is used to track log items that have been committed but not
* yet written into the log. It is used only when the delayed logging mount
* option is enabled.
*
* This structure tracks the list of committing checkpoint contexts so
* we can avoid the problem of having to hold out new transactions during a
* flush until we have a the commit record LSN of the checkpoint. We can
* traverse the list of committing contexts in xlog_cil_push_lsn() to find a
* sequence match and extract the commit LSN directly from there. If the
* checkpoint is still in the process of committing, we can block waiting for
* the commit LSN to be determined as well. This should make synchronous
* operations almost as efficient as the old logging methods.
*/
struct xfs_cil {
struct xlog *xc_log;
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
struct list_head xc_cil;
spinlock_t xc_cil_lock;
struct rw_semaphore xc_ctx_lock ____cacheline_aligned_in_smp;
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
struct xfs_cil_ctx *xc_ctx;
spinlock_t xc_push_lock ____cacheline_aligned_in_smp;
xfs_lsn_t xc_push_seq;
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
struct list_head xc_committing;
wait_queue_head_t xc_commit_wait;
xfs: Reduce log force overhead for delayed logging Delayed logging adds some serialisation to the log force process to ensure that it does not deference a bad commit context structure when determining if a CIL push is necessary or not. It does this by grabing the CIL context lock exclusively, then dropping it before pushing the CIL if necessary. This causes serialisation of all log forces and pushes regardless of whether a force is necessary or not. As a result fsync heavy workloads (like dbench) can be significantly slower with delayed logging than without. To avoid this penalty, copy the current sequence from the context to the CIL structure when they are swapped. This allows us to do unlocked checks on the current sequence without having to worry about dereferencing context structures that may have already been freed. Hence we can remove the CIL context locking in the forcing code and only call into the push code if the current context matches the sequence we need to force. By passing the sequence into the push code, we can check the sequence again once we have the CIL lock held exclusive and abort if the sequence has already been pushed. This avoids a lock round-trip and unnecessary CIL pushes when we have racing push calls. The result is that the regression in dbench performance goes away - this change improves dbench performance on a ramdisk from ~2100MB/s to ~2500MB/s. This compares favourably to not using delayed logging which retuns ~2500MB/s for the same workload. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-08-24 01:40:03 +00:00
xfs_lsn_t xc_current_sequence;
struct work_struct xc_push_work;
} ____cacheline_aligned_in_smp;
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
/*
xfs: force background CIL push under sustained load I have been seeing occasional pauses in transaction throughput up to 30s long under heavy parallel workloads. The only notable thing was that the xfsaild was trying to be active during the pauses, but making no progress. It was running exactly 20 times a second (on the 50ms no-progress backoff), and the number of pushbuf events was constant across this time as well. IOWs, the xfsaild appeared to be stuck on buffers that it could not push out. Further investigation indicated that it was trying to push out inode buffers that were pinned and/or locked. The xfsbufd was also getting woken at the same frequency (by the xfsaild, no doubt) to push out delayed write buffers. The xfsbufd was not making any progress because all the buffers in the delwri queue were pinned. This scan- and-make-no-progress dance went one in the trace for some seconds, before the xfssyncd came along an issued a log force, and then things started going again. However, I noticed something strange about the log force - there were way too many IO's issued. 516 log buffers were written, to be exact. That added up to 129MB of log IO, which got me very interested because it's almost exactly 25% of the size of the log. He delayed logging code is suppose to aggregate the minimum of 25% of the log or 8MB worth of changes before flushing. That's what really puzzled me - why did a log force write 129MB instead of only 8MB? Essentially what has happened is that no CIL pushes had occurred since the previous tail push which cleared out 25% of the log space. That caused all the new transactions to block because there wasn't log space for them, but they kick the xfsaild to push the tail. However, the xfsaild was not making progress because there were buffers it could not lock and flush, and the xfsbufd could not flush them because they were pinned. As a result, both the xfsaild and the xfsbufd could not move the tail of the log forward without the CIL first committing. The cause of the problem was that the background CIL push, which should happen when 8MB of aggregated changes have been committed, is being held off by the concurrent transaction commit load. The background push does a down_write_trylock() which will fail if there is a concurrent transaction commit holding the push lock in read mode. With 8 CPUs all doing transactions as fast as they can, there was enough concurrent transaction commits to hold off the background push until tail-pushing could no longer free log space, and the halt would occur. It should be noted that there is no reason why it would halt at 25% of log space used by a single CIL checkpoint. This bug could definitely violate the "no transaction should be larger than half the log" requirement and hence result in corruption if the system crashed under heavy load. This sort of bug is exactly the reason why delayed logging was tagged as experimental.... The fix is to start blocking background pushes once the threshold has been exceeded. Rework the threshold calculations to keep the amount of log space a CIL checkpoint can use to below that of the AIL push threshold to avoid the problem completely. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Alex Elder <aelder@sgi.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-09-24 08:13:44 +00:00
* The amount of log space we allow the CIL to aggregate is difficult to size.
* Whatever we choose, we have to make sure we can get a reservation for the
* log space effectively, that it is large enough to capture sufficient
* relogging to reduce log buffer IO significantly, but it is not too large for
* the log or induces too much latency when writing out through the iclogs. We
* track both space consumed and the number of vectors in the checkpoint
* context, so we need to decide which to use for limiting.
*
* Every log buffer we write out during a push needs a header reserved, which
* is at least one sector and more for v2 logs. Hence we need a reservation of
* at least 512 bytes per 32k of log space just for the LR headers. That means
* 16KB of reservation per megabyte of delayed logging space we will consume,
* plus various headers. The number of headers will vary based on the num of
* io vectors, so limiting on a specific number of vectors is going to result
* in transactions of varying size. IOWs, it is more consistent to track and
* limit space consumed in the log rather than by the number of objects being
* logged in order to prevent checkpoint ticket overruns.
*
* Further, use of static reservations through the log grant mechanism is
* problematic. It introduces a lot of complexity (e.g. reserve grant vs write
* grant) and a significant deadlock potential because regranting write space
* can block on log pushes. Hence if we have to regrant log space during a log
* push, we can deadlock.
*
* However, we can avoid this by use of a dynamic "reservation stealing"
* technique during transaction commit whereby unused reservation space in the
* transaction ticket is transferred to the CIL ctx commit ticket to cover the
* space needed by the checkpoint transaction. This means that we never need to
* specifically reserve space for the CIL checkpoint transaction, nor do we
* need to regrant space once the checkpoint completes. This also means the
* checkpoint transaction ticket is specific to the checkpoint context, rather
* than the CIL itself.
*
xfs: force background CIL push under sustained load I have been seeing occasional pauses in transaction throughput up to 30s long under heavy parallel workloads. The only notable thing was that the xfsaild was trying to be active during the pauses, but making no progress. It was running exactly 20 times a second (on the 50ms no-progress backoff), and the number of pushbuf events was constant across this time as well. IOWs, the xfsaild appeared to be stuck on buffers that it could not push out. Further investigation indicated that it was trying to push out inode buffers that were pinned and/or locked. The xfsbufd was also getting woken at the same frequency (by the xfsaild, no doubt) to push out delayed write buffers. The xfsbufd was not making any progress because all the buffers in the delwri queue were pinned. This scan- and-make-no-progress dance went one in the trace for some seconds, before the xfssyncd came along an issued a log force, and then things started going again. However, I noticed something strange about the log force - there were way too many IO's issued. 516 log buffers were written, to be exact. That added up to 129MB of log IO, which got me very interested because it's almost exactly 25% of the size of the log. He delayed logging code is suppose to aggregate the minimum of 25% of the log or 8MB worth of changes before flushing. That's what really puzzled me - why did a log force write 129MB instead of only 8MB? Essentially what has happened is that no CIL pushes had occurred since the previous tail push which cleared out 25% of the log space. That caused all the new transactions to block because there wasn't log space for them, but they kick the xfsaild to push the tail. However, the xfsaild was not making progress because there were buffers it could not lock and flush, and the xfsbufd could not flush them because they were pinned. As a result, both the xfsaild and the xfsbufd could not move the tail of the log forward without the CIL first committing. The cause of the problem was that the background CIL push, which should happen when 8MB of aggregated changes have been committed, is being held off by the concurrent transaction commit load. The background push does a down_write_trylock() which will fail if there is a concurrent transaction commit holding the push lock in read mode. With 8 CPUs all doing transactions as fast as they can, there was enough concurrent transaction commits to hold off the background push until tail-pushing could no longer free log space, and the halt would occur. It should be noted that there is no reason why it would halt at 25% of log space used by a single CIL checkpoint. This bug could definitely violate the "no transaction should be larger than half the log" requirement and hence result in corruption if the system crashed under heavy load. This sort of bug is exactly the reason why delayed logging was tagged as experimental.... The fix is to start blocking background pushes once the threshold has been exceeded. Rework the threshold calculations to keep the amount of log space a CIL checkpoint can use to below that of the AIL push threshold to avoid the problem completely. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Alex Elder <aelder@sgi.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-09-24 08:13:44 +00:00
* With dynamic reservations, we can effectively make up arbitrary limits for
* the checkpoint size so long as they don't violate any other size rules.
* Recovery imposes a rule that no transaction exceed half the log, so we are
* limited by that. Furthermore, the log transaction reservation subsystem
* tries to keep 25% of the log free, so we need to keep below that limit or we
* risk running out of free log space to start any new transactions.
*
* In order to keep background CIL push efficient, we will set a lower
* threshold at which background pushing is attempted without blocking current
* transaction commits. A separate, higher bound defines when CIL pushes are
* enforced to ensure we stay within our maximum checkpoint size bounds.
* threshold, yet give us plenty of space for aggregation on large logs.
*/
xfs: force background CIL push under sustained load I have been seeing occasional pauses in transaction throughput up to 30s long under heavy parallel workloads. The only notable thing was that the xfsaild was trying to be active during the pauses, but making no progress. It was running exactly 20 times a second (on the 50ms no-progress backoff), and the number of pushbuf events was constant across this time as well. IOWs, the xfsaild appeared to be stuck on buffers that it could not push out. Further investigation indicated that it was trying to push out inode buffers that were pinned and/or locked. The xfsbufd was also getting woken at the same frequency (by the xfsaild, no doubt) to push out delayed write buffers. The xfsbufd was not making any progress because all the buffers in the delwri queue were pinned. This scan- and-make-no-progress dance went one in the trace for some seconds, before the xfssyncd came along an issued a log force, and then things started going again. However, I noticed something strange about the log force - there were way too many IO's issued. 516 log buffers were written, to be exact. That added up to 129MB of log IO, which got me very interested because it's almost exactly 25% of the size of the log. He delayed logging code is suppose to aggregate the minimum of 25% of the log or 8MB worth of changes before flushing. That's what really puzzled me - why did a log force write 129MB instead of only 8MB? Essentially what has happened is that no CIL pushes had occurred since the previous tail push which cleared out 25% of the log space. That caused all the new transactions to block because there wasn't log space for them, but they kick the xfsaild to push the tail. However, the xfsaild was not making progress because there were buffers it could not lock and flush, and the xfsbufd could not flush them because they were pinned. As a result, both the xfsaild and the xfsbufd could not move the tail of the log forward without the CIL first committing. The cause of the problem was that the background CIL push, which should happen when 8MB of aggregated changes have been committed, is being held off by the concurrent transaction commit load. The background push does a down_write_trylock() which will fail if there is a concurrent transaction commit holding the push lock in read mode. With 8 CPUs all doing transactions as fast as they can, there was enough concurrent transaction commits to hold off the background push until tail-pushing could no longer free log space, and the halt would occur. It should be noted that there is no reason why it would halt at 25% of log space used by a single CIL checkpoint. This bug could definitely violate the "no transaction should be larger than half the log" requirement and hence result in corruption if the system crashed under heavy load. This sort of bug is exactly the reason why delayed logging was tagged as experimental.... The fix is to start blocking background pushes once the threshold has been exceeded. Rework the threshold calculations to keep the amount of log space a CIL checkpoint can use to below that of the AIL push threshold to avoid the problem completely. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Alex Elder <aelder@sgi.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-09-24 08:13:44 +00:00
#define XLOG_CIL_SPACE_LIMIT(log) (log->l_logsize >> 3)
/*
* ticket grant locks, queues and accounting have their own cachlines
* as these are quite hot and can be operated on concurrently.
*/
struct xlog_grant_head {
spinlock_t lock ____cacheline_aligned_in_smp;
struct list_head waiters;
atomic64_t grant;
};
/*
* The reservation head lsn is not made up of a cycle number and block number.
* Instead, it uses a cycle number and byte number. Logs don't expect to
* overflow 31 bits worth of byte offset, so using a byte number will mean
* that round off problems won't occur when releasing partial reservations.
*/
struct xlog {
/* The following fields don't need locking */
struct xfs_mount *l_mp; /* mount point */
struct xfs_ail *l_ailp; /* AIL log is working with */
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
struct xfs_cil *l_cilp; /* CIL log is working with */
struct xfs_buf *l_xbuf; /* extra buffer for log
* wrapping */
struct xfs_buftarg *l_targ; /* buftarg of log */
struct delayed_work l_work; /* background flush work */
uint l_flags;
uint l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */
struct list_head *l_buf_cancel_table;
int l_iclog_hsize; /* size of iclog header */
int l_iclog_heads; /* # of iclog header sectors */
uint l_sectBBsize; /* sector size in BBs (2^n) */
int l_iclog_size; /* size of log in bytes */
int l_iclog_size_log; /* log power size of log */
int l_iclog_bufs; /* number of iclog buffers */
xfs_daddr_t l_logBBstart; /* start block of log */
int l_logsize; /* size of log in bytes */
int l_logBBsize; /* size of log in BB chunks */
/* The following block of fields are changed while holding icloglock */
wait_queue_head_t l_flush_wait ____cacheline_aligned_in_smp;
/* waiting for iclog flush */
int l_covered_state;/* state of "covering disk
* log entries" */
xlog_in_core_t *l_iclog; /* head log queue */
spinlock_t l_icloglock; /* grab to change iclog state */
int l_curr_cycle; /* Cycle number of log writes */
int l_prev_cycle; /* Cycle number before last
* block increment */
int l_curr_block; /* current logical log block */
int l_prev_block; /* previous logical log block */
/*
* l_last_sync_lsn and l_tail_lsn are atomics so they can be set and
* read without needing to hold specific locks. To avoid operations
* contending with other hot objects, place each of them on a separate
* cacheline.
*/
/* lsn of last LR on disk */
atomic64_t l_last_sync_lsn ____cacheline_aligned_in_smp;
/* lsn of 1st LR with unflushed * buffers */
atomic64_t l_tail_lsn ____cacheline_aligned_in_smp;
struct xlog_grant_head l_reserve_head;
struct xlog_grant_head l_write_head;
struct xfs_kobj l_kobj;
/* The following field are used for debugging; need to hold icloglock */
#ifdef DEBUG
void *l_iclog_bak[XLOG_MAX_ICLOGS];
/* log record crc error injection factor */
uint32_t l_badcrc_factor;
#endif
/* log recovery lsn tracking (for buffer submission */
xfs_lsn_t l_recovery_lsn;
};
#define XLOG_BUF_CANCEL_BUCKET(log, blkno) \
((log)->l_buf_cancel_table + ((uint64_t)blkno % XLOG_BC_TABLE_SIZE))
#define XLOG_FORCED_SHUTDOWN(log) ((log)->l_flags & XLOG_IO_ERROR)
/* common routines */
extern int
xlog_recover(
struct xlog *log);
extern int
xlog_recover_finish(
struct xlog *log);
extern int
xlog_recover_cancel(struct xlog *);
2012-11-12 11:54:24 +00:00
extern __le32 xlog_cksum(struct xlog *log, struct xlog_rec_header *rhead,
2012-11-12 11:54:24 +00:00
char *dp, int size);
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
extern kmem_zone_t *xfs_log_ticket_zone;
struct xlog_ticket *
xlog_ticket_alloc(
struct xlog *log,
int unit_bytes,
int count,
char client,
bool permanent,
xfs_km_flags_t alloc_flags);
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
static inline void
xlog_write_adv_cnt(void **ptr, int *len, int *off, size_t bytes)
{
*ptr += bytes;
*len -= bytes;
*off += bytes;
}
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
void xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket);
void xlog_print_trans(struct xfs_trans *);
int
xlog_write(
struct xlog *log,
struct xfs_log_vec *log_vector,
struct xlog_ticket *tic,
xfs_lsn_t *start_lsn,
struct xlog_in_core **commit_iclog,
uint flags);
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
/*
* When we crack an atomic LSN, we sample it first so that the value will not
* change while we are cracking it into the component values. This means we
* will always get consistent component values to work from. This should always
* be used to sample and crack LSNs that are stored and updated in atomic
* variables.
*/
static inline void
xlog_crack_atomic_lsn(atomic64_t *lsn, uint *cycle, uint *block)
{
xfs_lsn_t val = atomic64_read(lsn);
*cycle = CYCLE_LSN(val);
*block = BLOCK_LSN(val);
}
/*
* Calculate and assign a value to an atomic LSN variable from component pieces.
*/
static inline void
xlog_assign_atomic_lsn(atomic64_t *lsn, uint cycle, uint block)
{
atomic64_set(lsn, xlog_assign_lsn(cycle, block));
}
/*
* When we crack the grant head, we sample it first so that the value will not
* change while we are cracking it into the component values. This means we
* will always get consistent component values to work from.
*/
static inline void
xlog_crack_grant_head_val(int64_t val, int *cycle, int *space)
{
*cycle = val >> 32;
*space = val & 0xffffffff;
}
static inline void
xlog_crack_grant_head(atomic64_t *head, int *cycle, int *space)
{
xlog_crack_grant_head_val(atomic64_read(head), cycle, space);
}
static inline int64_t
xlog_assign_grant_head_val(int cycle, int space)
{
return ((int64_t)cycle << 32) | space;
}
static inline void
xlog_assign_grant_head(atomic64_t *head, int cycle, int space)
{
atomic64_set(head, xlog_assign_grant_head_val(cycle, space));
}
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
/*
* Committed Item List interfaces
*/
xfs: prevent deadlock trying to cover an active log Recent analysis of a deadlocked XFS filesystem from a kernel crash dump indicated that the filesystem was stuck waiting for log space. The short story of the hang on the RHEL6 kernel is this: - the tail of the log is pinned by an inode - the inode has been pushed by the xfsaild - the inode has been flushed to it's backing buffer and is currently flush locked and hence waiting for backing buffer IO to complete and remove it from the AIL - the backing buffer is marked for write - it is on the delayed write queue - the inode buffer has been modified directly and logged recently due to unlinked inode list modification - the backing buffer is pinned in memory as it is in the active CIL context. - the xfsbufd won't start buffer writeback because it is pinned - xfssyncd won't force the log because it sees the log as needing to be covered and hence wants to issue a dummy transaction to move the log covering state machine along. Hence there is no trigger to force the CIL to the log and hence unpin the inode buffer and therefore complete the inode IO, remove it from the AIL and hence move the tail of the log along, allowing transactions to start again. Mainline kernels also have the same deadlock, though the signature is slightly different - the inode buffer never reaches the delayed write lists because xfs_buf_item_push() sees that it is pinned and hence never adds it to the delayed write list that the xfsaild flushes. There are two possible solutions here. The first is to simply force the log before trying to cover the log and so ensure that the CIL is emptied before we try to reserve space for the dummy transaction in the xfs_log_worker(). While this might work most of the time, it is still racy and is no guarantee that we don't get stuck in xfs_trans_reserve waiting for log space to come free. Hence it's not the best way to solve the problem. The second solution is to modify xfs_log_need_covered() to be aware of the CIL. We only should be attempting to cover the log if there is no current activity in the log - covering the log is the process of ensuring that the head and tail in the log on disk are identical (i.e. the log is clean and at idle). Hence, by definition, if there are items in the CIL then the log is not at idle and so we don't need to attempt to cover it. When we don't need to cover the log because it is active or idle, we issue a log force from xfs_log_worker() - if the log is idle, then this does nothing. However, if the log is active due to there being items in the CIL, it will force the items in the CIL to the log and unpin them. In the case of the above deadlock scenario, instead of xfs_log_worker() getting stuck in xfs_trans_reserve() attempting to cover the log, it will instead force the log, thereby unpinning the inode buffer, allowing IO to be issued and complete and hence removing the inode that was pinning the tail of the log from the AIL. At that point, everything will start moving along again. i.e. the xfs_log_worker turns back into a watchdog that can alleviate deadlocks based around pinned items that prevent the tail of the log from being moved... Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-10-14 22:17:49 +00:00
int xlog_cil_init(struct xlog *log);
void xlog_cil_init_post_recovery(struct xlog *log);
void xlog_cil_destroy(struct xlog *log);
bool xlog_cil_empty(struct xlog *log);
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
xfs: Reduce log force overhead for delayed logging Delayed logging adds some serialisation to the log force process to ensure that it does not deference a bad commit context structure when determining if a CIL push is necessary or not. It does this by grabing the CIL context lock exclusively, then dropping it before pushing the CIL if necessary. This causes serialisation of all log forces and pushes regardless of whether a force is necessary or not. As a result fsync heavy workloads (like dbench) can be significantly slower with delayed logging than without. To avoid this penalty, copy the current sequence from the context to the CIL structure when they are swapped. This allows us to do unlocked checks on the current sequence without having to worry about dereferencing context structures that may have already been freed. Hence we can remove the CIL context locking in the forcing code and only call into the push code if the current context matches the sequence we need to force. By passing the sequence into the push code, we can check the sequence again once we have the CIL lock held exclusive and abort if the sequence has already been pushed. This avoids a lock round-trip and unnecessary CIL pushes when we have racing push calls. The result is that the regression in dbench performance goes away - this change improves dbench performance on a ramdisk from ~2100MB/s to ~2500MB/s. This compares favourably to not using delayed logging which retuns ~2500MB/s for the same workload. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-08-24 01:40:03 +00:00
/*
* CIL force routines
*/
xfs_lsn_t
xlog_cil_force_lsn(
struct xlog *log,
xfs_lsn_t sequence);
xfs: Reduce log force overhead for delayed logging Delayed logging adds some serialisation to the log force process to ensure that it does not deference a bad commit context structure when determining if a CIL push is necessary or not. It does this by grabing the CIL context lock exclusively, then dropping it before pushing the CIL if necessary. This causes serialisation of all log forces and pushes regardless of whether a force is necessary or not. As a result fsync heavy workloads (like dbench) can be significantly slower with delayed logging than without. To avoid this penalty, copy the current sequence from the context to the CIL structure when they are swapped. This allows us to do unlocked checks on the current sequence without having to worry about dereferencing context structures that may have already been freed. Hence we can remove the CIL context locking in the forcing code and only call into the push code if the current context matches the sequence we need to force. By passing the sequence into the push code, we can check the sequence again once we have the CIL lock held exclusive and abort if the sequence has already been pushed. This avoids a lock round-trip and unnecessary CIL pushes when we have racing push calls. The result is that the regression in dbench performance goes away - this change improves dbench performance on a ramdisk from ~2100MB/s to ~2500MB/s. This compares favourably to not using delayed logging which retuns ~2500MB/s for the same workload. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-08-24 01:40:03 +00:00
static inline void
xlog_cil_force(struct xlog *log)
xfs: Reduce log force overhead for delayed logging Delayed logging adds some serialisation to the log force process to ensure that it does not deference a bad commit context structure when determining if a CIL push is necessary or not. It does this by grabing the CIL context lock exclusively, then dropping it before pushing the CIL if necessary. This causes serialisation of all log forces and pushes regardless of whether a force is necessary or not. As a result fsync heavy workloads (like dbench) can be significantly slower with delayed logging than without. To avoid this penalty, copy the current sequence from the context to the CIL structure when they are swapped. This allows us to do unlocked checks on the current sequence without having to worry about dereferencing context structures that may have already been freed. Hence we can remove the CIL context locking in the forcing code and only call into the push code if the current context matches the sequence we need to force. By passing the sequence into the push code, we can check the sequence again once we have the CIL lock held exclusive and abort if the sequence has already been pushed. This avoids a lock round-trip and unnecessary CIL pushes when we have racing push calls. The result is that the regression in dbench performance goes away - this change improves dbench performance on a ramdisk from ~2100MB/s to ~2500MB/s. This compares favourably to not using delayed logging which retuns ~2500MB/s for the same workload. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-08-24 01:40:03 +00:00
{
xlog_cil_force_lsn(log, log->l_cilp->xc_current_sequence);
}
xfs: Introduce delayed logging core code The delayed logging code only changes in-memory structures and as such can be enabled and disabled with a mount option. Add the mount option and emit a warning that this is an experimental feature that should not be used in production yet. We also need infrastructure to track committed items that have not yet been written to the log. This is what the Committed Item List (CIL) is for. The log item also needs to be extended to track the current log vector, the associated memory buffer and it's location in the Commit Item List. Extend the log item and log vector structures to enable this tracking. To maintain the current log format for transactions with delayed logging, we need to introduce a checkpoint transaction and a context for tracking each checkpoint from initiation to transaction completion. This includes adding a log ticket for tracking space log required/used by the context checkpoint. To track all the changes we need an io vector array per log item, rather than a single array for the entire transaction. Using the new log vector structure for this requires two passes - the first to allocate the log vector structures and chain them together, and the second to fill them out. This log vector chain can then be passed to the CIL for formatting, pinning and insertion into the CIL. Formatting of the log vector chain is relatively simple - it's just a loop over the iovecs on each log vector, but it is made slightly more complex because we re-write the iovec after the copy to point back at the memory buffer we just copied into. This code also needs to pin log items. If the log item is not already tracked in this checkpoint context, then it needs to be pinned. Otherwise it is already pinned and we don't need to pin it again. The only other complexity is calculating the amount of new log space the formatting has consumed. This needs to be accounted to the transaction in progress, and the accounting is made more complex becase we need also to steal space from it for log metadata in the checkpoint transaction. Calculate all this at insert time and update all the tickets, counters, etc correctly. Once we've formatted all the log items in the transaction, attach the busy extents to the checkpoint context so the busy extents live until checkpoint completion and can be processed at that point in time. Transactions can then be freed at this point in time. Now we need to issue checkpoints - we are tracking the amount of log space used by the items in the CIL, so we can trigger background checkpoints when the space usage gets to a certain threshold. Otherwise, checkpoints need ot be triggered when a log synchronisation point is reached - a log force event. Because the log write code already handles chained log vectors, writing the transaction is trivial, too. Construct a transaction header, add it to the head of the chain and write it into the log, then issue a commit record write. Then we can release the checkpoint log ticket and attach the context to the log buffer so it can be called during Io completion to complete the checkpoint. We also need to allow for synchronising multiple in-flight checkpoints. This is needed for two things - the first is to ensure that checkpoint commit records appear in the log in the correct sequence order (so they are replayed in the correct order). The second is so that xfs_log_force_lsn() operates correctly and only flushes and/or waits for the specific sequence it was provided with. To do this we need a wait variable and a list tracking the checkpoint commits in progress. We can walk this list and wait for the checkpoints to change state or complete easily, an this provides the necessary synchronisation for correct operation in both cases. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-21 04:37:18 +00:00
/*
* Unmount record type is used as a pseudo transaction type for the ticket.
* It's value must be outside the range of XFS_TRANS_* values.
*/
#define XLOG_UNMOUNT_REC_TYPE (-1U)
/*
* Wrapper function for waiting on a wait queue serialised against wakeups
* by a spinlock. This matches the semantics of all the wait queues used in the
* log code.
*/
static inline void xlog_wait(wait_queue_head_t *wq, spinlock_t *lock)
{
DECLARE_WAITQUEUE(wait, current);
add_wait_queue_exclusive(wq, &wait);
__set_current_state(TASK_UNINTERRUPTIBLE);
spin_unlock(lock);
schedule();
remove_wait_queue(wq, &wait);
}
xfs: validate metadata LSNs against log on v5 superblocks Since the onset of v5 superblocks, the LSN of the last modification has been included in a variety of on-disk data structures. This LSN is used to provide log recovery ordering guarantees (e.g., to ensure an older log recovery item is not replayed over a newer target data structure). While this works correctly from the point a filesystem is formatted and mounted, userspace tools have some problematic behaviors that defeat this mechanism. For example, xfs_repair historically zeroes out the log unconditionally (regardless of whether corruption is detected). If this occurs, the LSN of the filesystem is reset and the log is now in a problematic state with respect to on-disk metadata structures that might have a larger LSN. Until either the log catches up to the highest previously used metadata LSN or each affected data structure is modified and written out without incident (which resets the metadata LSN), log recovery is susceptible to filesystem corruption. This problem is ultimately addressed and repaired in the associated userspace tools. The kernel is still responsible to detect the problem and notify the user that something is wrong. Check the superblock LSN at mount time and fail the mount if it is invalid. From that point on, trigger verifier failure on any metadata I/O where an invalid LSN is detected. This results in a filesystem shutdown and guarantees that we do not log metadata changes with invalid LSNs on disk. Since this is a known issue with a known recovery path, present a warning to instruct the user how to recover. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
2015-10-12 04:59:25 +00:00
/*
* The LSN is valid so long as it is behind the current LSN. If it isn't, this
* means that the next log record that includes this metadata could have a
* smaller LSN. In turn, this means that the modification in the log would not
* replay.
*/
static inline bool
xlog_valid_lsn(
struct xlog *log,
xfs_lsn_t lsn)
{
int cur_cycle;
int cur_block;
bool valid = true;
/*
* First, sample the current lsn without locking to avoid added
* contention from metadata I/O. The current cycle and block are updated
* (in xlog_state_switch_iclogs()) and read here in a particular order
* to avoid false negatives (e.g., thinking the metadata LSN is valid
* when it is not).
*
* The current block is always rewound before the cycle is bumped in
* xlog_state_switch_iclogs() to ensure the current LSN is never seen in
* a transiently forward state. Instead, we can see the LSN in a
* transiently behind state if we happen to race with a cycle wrap.
*/
locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE() Please do not apply this to mainline directly, instead please re-run the coccinelle script shown below and apply its output. For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't harmful, and changing them results in churn. However, for some features, the read/write distinction is critical to correct operation. To distinguish these cases, separate read/write accessors must be used. This patch migrates (most) remaining ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following coccinelle script: ---- // Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and // WRITE_ONCE() // $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: davem@davemloft.net Cc: linux-arch@vger.kernel.org Cc: mpe@ellerman.id.au Cc: shuah@kernel.org Cc: snitzer@redhat.com Cc: thor.thayer@linux.intel.com Cc: tj@kernel.org Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-23 21:07:29 +00:00
cur_cycle = READ_ONCE(log->l_curr_cycle);
xfs: validate metadata LSNs against log on v5 superblocks Since the onset of v5 superblocks, the LSN of the last modification has been included in a variety of on-disk data structures. This LSN is used to provide log recovery ordering guarantees (e.g., to ensure an older log recovery item is not replayed over a newer target data structure). While this works correctly from the point a filesystem is formatted and mounted, userspace tools have some problematic behaviors that defeat this mechanism. For example, xfs_repair historically zeroes out the log unconditionally (regardless of whether corruption is detected). If this occurs, the LSN of the filesystem is reset and the log is now in a problematic state with respect to on-disk metadata structures that might have a larger LSN. Until either the log catches up to the highest previously used metadata LSN or each affected data structure is modified and written out without incident (which resets the metadata LSN), log recovery is susceptible to filesystem corruption. This problem is ultimately addressed and repaired in the associated userspace tools. The kernel is still responsible to detect the problem and notify the user that something is wrong. Check the superblock LSN at mount time and fail the mount if it is invalid. From that point on, trigger verifier failure on any metadata I/O where an invalid LSN is detected. This results in a filesystem shutdown and guarantees that we do not log metadata changes with invalid LSNs on disk. Since this is a known issue with a known recovery path, present a warning to instruct the user how to recover. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
2015-10-12 04:59:25 +00:00
smp_rmb();
locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE() Please do not apply this to mainline directly, instead please re-run the coccinelle script shown below and apply its output. For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't harmful, and changing them results in churn. However, for some features, the read/write distinction is critical to correct operation. To distinguish these cases, separate read/write accessors must be used. This patch migrates (most) remaining ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following coccinelle script: ---- // Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and // WRITE_ONCE() // $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: davem@davemloft.net Cc: linux-arch@vger.kernel.org Cc: mpe@ellerman.id.au Cc: shuah@kernel.org Cc: snitzer@redhat.com Cc: thor.thayer@linux.intel.com Cc: tj@kernel.org Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-23 21:07:29 +00:00
cur_block = READ_ONCE(log->l_curr_block);
xfs: validate metadata LSNs against log on v5 superblocks Since the onset of v5 superblocks, the LSN of the last modification has been included in a variety of on-disk data structures. This LSN is used to provide log recovery ordering guarantees (e.g., to ensure an older log recovery item is not replayed over a newer target data structure). While this works correctly from the point a filesystem is formatted and mounted, userspace tools have some problematic behaviors that defeat this mechanism. For example, xfs_repair historically zeroes out the log unconditionally (regardless of whether corruption is detected). If this occurs, the LSN of the filesystem is reset and the log is now in a problematic state with respect to on-disk metadata structures that might have a larger LSN. Until either the log catches up to the highest previously used metadata LSN or each affected data structure is modified and written out without incident (which resets the metadata LSN), log recovery is susceptible to filesystem corruption. This problem is ultimately addressed and repaired in the associated userspace tools. The kernel is still responsible to detect the problem and notify the user that something is wrong. Check the superblock LSN at mount time and fail the mount if it is invalid. From that point on, trigger verifier failure on any metadata I/O where an invalid LSN is detected. This results in a filesystem shutdown and guarantees that we do not log metadata changes with invalid LSNs on disk. Since this is a known issue with a known recovery path, present a warning to instruct the user how to recover. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
2015-10-12 04:59:25 +00:00
if ((CYCLE_LSN(lsn) > cur_cycle) ||
(CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block)) {
/*
* If the metadata LSN appears invalid, it's possible the check
* above raced with a wrap to the next log cycle. Grab the lock
* to check for sure.
*/
spin_lock(&log->l_icloglock);
cur_cycle = log->l_curr_cycle;
cur_block = log->l_curr_block;
spin_unlock(&log->l_icloglock);
if ((CYCLE_LSN(lsn) > cur_cycle) ||
(CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block))
valid = false;
}
return valid;
}
#endif /* __XFS_LOG_PRIV_H__ */