Christoph Hellwig pointed out that there's a potentially nasty race when
performing simultaneous nearby directio cow writes:
"Thread 1 writes a range from B to c
" B --------- C
p
"a little later thread 2 writes from A to B
" A --------- B
p
[editor's note: the 'p' denote cowextsize boundaries, which I added to
make this more clear]
"but the code preallocates beyond B into the range where thread
"1 has just written, but ->end_io hasn't been called yet.
"But once ->end_io is called thread 2 has already allocated
"up to the extent size hint into the write range of thread 1,
"so the end_io handler will splice the unintialized blocks from
"that preallocation back into the file right after B."
We can avoid this race by ensuring that thread 1 cannot accidentally
remap the blocks that thread 2 allocated (as part of speculative
preallocation) as part of t2's write preparation in t1's end_io handler.
The way we make this happen is by taking advantage of the unwritten
extent flag as an intermediate step.
Recall that when we begin the process of writing data to shared blocks,
we create a delayed allocation extent in the CoW fork:
D: --RRRRRRSSSRRRRRRRR---
C: ------DDDDDDD---------
When a thread prepares to CoW some dirty data out to disk, it will now
convert the delalloc reservation into an /unwritten/ allocated extent in
the cow fork. The da conversion code tries to opportunistically
allocate as much of a (speculatively prealloc'd) extent as possible, so
we may end up allocating a larger extent than we're actually writing
out:
D: --RRRRRRSSSRRRRRRRR---
U: ------UUUUUUU---------
Next, we convert only the part of the extent that we're actively
planning to write to normal (i.e. not unwritten) status:
D: --RRRRRRSSSRRRRRRRR---
U: ------UURRUUU---------
If the write succeeds, the end_cow function will now scan the relevant
range of the CoW fork for real extents and remap only the real extents
into the data fork:
D: --RRRRRRRRSRRRRRRRR---
U: ------UU--UUU---------
This ensures that we never obliterate valid data fork extents with
unwritten blocks from the CoW fork.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Commit 99579ccec4 "xfs: skip dirty pages in ->releasepage()" started
to skip dirty pages in xfs_vm_releasepage() which also has the effect
that if a dirty page is truncated, it does not get freed by
block_invalidatepage() and is lingering in LRU list waiting for reclaim.
So a simple loop like:
while true; do
dd if=/dev/zero of=file bs=1M count=100
rm file
done
will keep using more and more memory until we hit low watermarks and
start pagecache reclaim which will eventually reclaim also the truncate
pages. Keeping these truncated (and thus never usable) pages in memory
is just a waste of memory, is unnecessarily stressing page cache
reclaim, and reportedly also leads to anonymous mmap(2) returning ENOMEM
prematurely.
So instead of just skipping dirty pages in xfs_vm_releasepage(), return
to old behavior of skipping them only if they have delalloc or unwritten
buffers and fix the spurious warnings by warning only if the page is
clean.
CC: stable@vger.kernel.org
CC: Brian Foster <bfoster@redhat.com>
CC: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Petr Tůma <petr.tuma@d3s.mff.cuni.cz>
Fixes: 99579ccec4
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Contained in this update:
- DAX PMD vaults via iomap infrastructure
- Direct-io support in iomap infrastructure
- removal of now-redundant XFS inode iolock, replaced with VFS i_rwsem
- synchronisation with fixes and changes in userspace libxfs code
- extent tree lookup helpers
- lots of little corruption detection improvements to verifiers
- optimised CRC calculations
- faster buffer cache lookups
- deprecation of barrier/nobarrier mount options - we always use
REQ_FUA/REQ_FLUSH where appropriate for data integrity now
- cleanups to speculative preallocation
- miscellaneous minor bug fixes and cleanups
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Merge tag 'xfs-for-linus-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs
Pull xfs updates from Dave Chinner:
"There is quite a varied bunch of stuff in this update, and some of it
you will have already merged through the ext4 tree which imported the
dax-4.10-iomap-pmd topic branch from the XFS tree.
There is also a new direct IO implementation that uses the iomap
infrastructure. It's much simpler, faster, and has lower IO latency
than the existing direct IO infrastructure.
Summary:
- DAX PMD faults via iomap infrastructure
- Direct-io support in iomap infrastructure
- removal of now-redundant XFS inode iolock, replaced with VFS
i_rwsem
- synchronisation with fixes and changes in userspace libxfs code
- extent tree lookup helpers
- lots of little corruption detection improvements to verifiers
- optimised CRC calculations
- faster buffer cache lookups
- deprecation of barrier/nobarrier mount options - we always use
REQ_FUA/REQ_FLUSH where appropriate for data integrity now
- cleanups to speculative preallocation
- miscellaneous minor bug fixes and cleanups"
* tag 'xfs-for-linus-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs: (63 commits)
xfs: nuke unused tracepoint definitions
xfs: use GPF_NOFS when allocating btree cursors
xfs: use xfs_vn_setattr_size to check on new size
xfs: deprecate barrier/nobarrier mount option
xfs: Always flush caches when integrity is required
xfs: ignore leaf attr ichdr.count in verifier during log replay
xfs: use rhashtable to track buffer cache
xfs: optimise CRC updates
xfs: make xfs btree stats less huge
xfs: don't cap maximum dedupe request length
xfs: don't allow di_size with high bit set
xfs: error out if trying to add attrs and anextents > 0
xfs: don't crash if reading a directory results in an unexpected hole
xfs: complain if we don't get nextents bmap records
xfs: check for bogus values in btree block headers
xfs: forbid AG btrees with level == 0
xfs: several xattr functions can be void
xfs: handle cow fork in xfs_bmap_trace_exlist
xfs: pass state not whichfork to trace_xfs_extlist
xfs: Move AGI buffer type setting to xfs_read_agi
...
needed for both ext4 and xfs dax changes to use iomap for DAX. It
also includes the fscrypt branch which is needed for ubifs encryption
work as well as ext4 encryption and fscrypt cleanups.
Lots of cleanups and bug fixes, especially making sure ext4 is robust
against maliciously corrupted file systems --- especially maliciously
corrupted xattr blocks and a maliciously corrupted superblock. Also
fix ext4 support for 64k block sizes so it works well on ppcle. Fixed
mbcache so we don't miss some common xattr blocks that can be merged.
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Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o:
"This merge request includes the dax-4.0-iomap-pmd branch which is
needed for both ext4 and xfs dax changes to use iomap for DAX. It also
includes the fscrypt branch which is needed for ubifs encryption work
as well as ext4 encryption and fscrypt cleanups.
Lots of cleanups and bug fixes, especially making sure ext4 is robust
against maliciously corrupted file systems --- especially maliciously
corrupted xattr blocks and a maliciously corrupted superblock. Also
fix ext4 support for 64k block sizes so it works well on ppcle. Fixed
mbcache so we don't miss some common xattr blocks that can be merged"
* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (86 commits)
dax: Fix sleep in atomic contex in grab_mapping_entry()
fscrypt: Rename FS_WRITE_PATH_FL to FS_CTX_HAS_BOUNCE_BUFFER_FL
fscrypt: Delay bounce page pool allocation until needed
fscrypt: Cleanup page locking requirements for fscrypt_{decrypt,encrypt}_page()
fscrypt: Cleanup fscrypt_{decrypt,encrypt}_page()
fscrypt: Never allocate fscrypt_ctx on in-place encryption
fscrypt: Use correct index in decrypt path.
fscrypt: move the policy flags and encryption mode definitions to uapi header
fscrypt: move non-public structures and constants to fscrypt_private.h
fscrypt: unexport fscrypt_initialize()
fscrypt: rename get_crypt_info() to fscrypt_get_crypt_info()
fscrypto: move ioctl processing more fully into common code
fscrypto: remove unneeded Kconfig dependencies
MAINTAINERS: fscrypto: recommend linux-fsdevel for fscrypto patches
ext4: do not perform data journaling when data is encrypted
ext4: return -ENOMEM instead of success
ext4: reject inodes with negative size
ext4: remove another test in ext4_alloc_file_blocks()
Documentation: fix description of ext4's block_validity mount option
ext4: fix checks for data=ordered and journal_async_commit options
...
Straight switch over to using iomap for direct I/O - we already have the
non-COW dio path in write_begin for DAX and files with extent size hints,
so nothing to add there. The COW path is ported over from the old
get_blocks version and a bit of a mess, but I have some work in progress
to make it look more like the buffered I/O COW path.
This gets rid of xfs_get_blocks_direct and the last caller of
xfs_get_blocks with the create flag set, so all that code can be removed.
Last but not least I've removed a comment in xfs_filemap_fault that
refers to xfs_get_blocks entirely instead of updating it - while the
reference is correct, the whole DAX fault path looks different than
the non-DAX one, so it seems rather pointless.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This patch drops the XFS-own i_iolock and uses the VFS i_rwsem which
recently replaced i_mutex instead. This means we only have to take
one lock instead of two in many fast path operations, and we can
also shrink the xfs_inode structure. Thanks to the xfs_ilock family
there is very little churn, the only thing of note is that we need
to switch to use the lock_two_directory helper for taking the i_rwsem
on two inodes in a few places to make sure our lock order matches
the one used in the VFS.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Use xfs_iext_lookup_extent to look up the extent, drop a useless check,
drop a unneeded return value and clean up the general style a little bit.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
We've had reports of generic/095 causing XFS to BUG() in
__xfs_get_blocks() due to the existence of delalloc blocks on a
direct I/O read. generic/095 issues a mix of various types of I/O,
including direct and memory mapped I/O to a single file. This is
clearly not supported behavior and is known to lead to such
problems. E.g., the lack of exclusion between the direct I/O and
write fault paths means that a write fault can allocate delalloc
blocks in a region of a file that was previously a hole after the
direct read has attempted to flush/inval the file range, but before
it actually reads the block mapping. In turn, the direct read
discovers a delalloc extent and cannot proceed.
While the appropriate solution here is to not mix direct and memory
mapped I/O to the same regions of the same file, the current
BUG_ON() behavior is probably overkill as it can crash the entire
system. Instead, localize the failure to the I/O in question by
returning an error for a direct I/O that cannot be handled safely
due to delalloc blocks. Be careful to allow the case of a direct
write to post-eof delalloc blocks. This can occur due to speculative
preallocation and is safe as post-eof blocks are not accompanied by
dirty pages in pagecache (conversely, preallocation within eof must
have been zeroed, and thus dirtied, before the inode size could have
been increased beyond said blocks).
Finally, provide an additional warning if a direct I/O write occurs
while the file is memory mapped. This may not catch all problematic
scenarios, but provides a hint that some known-to-be-problematic I/O
methods are in use.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Switch xfs_filemap_pmd_fault() from using dax_pmd_fault() to the new and
improved dax_iomap_pmd_fault(). Also, now that it has no more users,
remove xfs_get_blocks_dax_fault().
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Add wbc_to_write_flags(), which returns the write modifier flags to use,
based on a struct writeback_control. No functional changes in this
patch, but it prepares us for factoring other wbc fields for write type.
Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Remove the WRITE_* and READ_SYNC wrappers, and just use the flags
directly. Where applicable this also drops usage of the
bio_set_op_attrs wrapper.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
We need to splice COW blocks we've completed in xfs_end_io_direct_write
into the data fork before converting unwritten extents. Otherwise
xfs_bmapi_write might first allocate blocks for any holes in the data
fork, which isn't only not needed but also harmful as it might cause
reserved block underruns in the transaction.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
For O_DIRECT writes to shared blocks, we have to CoW them just like
we would with buffered writes. For writes that are not block-aligned,
just bounce them to the page cache.
For block-aligned writes, however, we can do better than that. Use
the same mechanisms that we employ for buffered CoW to set up a
delalloc reservation, allocate all the blocks at once, issue the
writes against the new blocks and use the same ioend functions to
remap the blocks after the write. This should be fairly performant.
Christoph discovered that xfs_reflink_allocate_cow_range may stumble
over invalid entries in the extent array given that it drops the ilock
but still expects the index to be stable. Simple fixing it to a new
lookup for every iteration still isn't correct given that
xfs_bmapi_allocate will trigger a BUG_ON() if hitting a hole, and
there is nothing preventing a xfs_bunmapi_cow call removing extents
once we dropped the ilock either.
This patch duplicates the inner loop of xfs_bmapi_allocate into a
helper for xfs_reflink_allocate_cow_range so that it can be done under
the same ilock critical section as our CoW fork delayed allocation.
The directio CoW warts will be revisited in a later patch.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Report shared extents through the iomap interface so that FIEMAP flags
shared blocks accurately. Have xfs_vm_bmap return zero for reflinked
files because the bmap-based swap code requires static block mappings,
which is incompatible with copy on write.
NOTE: Existing userspace bmap users such as lilo will have the same
problem with reflink files.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
After the write component of a copy-write operation finishes, clean up
the bookkeeping left behind. On error, we simply free the new blocks
and pass the error up. If we succeed, however, then we must remove
the old data fork mapping and move the cow fork mapping to the data
fork.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
[hch: Call the CoW failure function during xfs_cancel_ioend]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Modify the writepage handler to find and convert pending delalloc
extents to real allocations. Furthermore, when we're doing non-cow
writes to a part of a file that already has a CoW reservation (the
cowextsz hint that we set up in a subsequent patch facilitates this),
promote the write to copy-on-write so that the entire extent can get
written out as a single extent on disk, thereby reducing post-CoW
fragmentation.
Christoph moved the CoW support code in _map_blocks to a separate helper
function, refactored other functions, and reduced the number of CoW fork
lookups, so I merged those changes here to reduce churn.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Modify xfs_bmap_add_extent_delay_real() so that we can convert delayed
allocation extents in the CoW fork to real allocations, and wire this
up all the way back to xfs_iomap_write_allocate(). In a subsequent
patch, we'll modify the writepage handler to call this.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Rename the current function to __xfs_setfilesize and add a non-static
wrapper that also takes care of creating the transaction. This new
helper will be used by the new iomap-based DAX path.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Changes in this update:
o generic iomap based IO path infrastructure
o generic iomap based fiemap implementation
o xfs iomap based Io path implementation
o buffer error handling fixes
o tracking of in flight buffer IO for unmount serialisation
o direct IO and DAX io path separation and simplification
o shortform directory format definition changes for wider platform compatibility
o various buffer cache fixes
o cleanups in preparation for rmap merge
o error injection cleanups and fixes
o log item format buffer memory allocation restructuring to prevent rare OOM
reclaim deadlocks
o sparse inode chunks are now fully supported.
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Merge tag 'xfs-for-linus-4.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs
Pull xfs updates from Dave Chinner:
"The major addition is the new iomap based block mapping
infrastructure. We've been kicking this about locally for years, but
there are other filesystems want to use it too (e.g. gfs2). Now it
is fully working, reviewed and ready for merge and be used by other
filesystems.
There are a lot of other fixes and cleanups in the tree, but those are
XFS internal things and none are of the scale or visibility of the
iomap changes. See below for details.
I am likely to send another pull request next week - we're just about
ready to merge some new functionality (on disk block->owner reverse
mapping infrastructure), but that's a huge chunk of code (74 files
changed, 7283 insertions(+), 1114 deletions(-)) so I'm keeping that
separate to all the "normal" pull request changes so they don't get
lost in the noise.
Summary of changes in this update:
- generic iomap based IO path infrastructure
- generic iomap based fiemap implementation
- xfs iomap based Io path implementation
- buffer error handling fixes
- tracking of in flight buffer IO for unmount serialisation
- direct IO and DAX io path separation and simplification
- shortform directory format definition changes for wider platform
compatibility
- various buffer cache fixes
- cleanups in preparation for rmap merge
- error injection cleanups and fixes
- log item format buffer memory allocation restructuring to prevent
rare OOM reclaim deadlocks
- sparse inode chunks are now fully supported"
* tag 'xfs-for-linus-4.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs: (53 commits)
xfs: remove EXPERIMENTAL tag from sparse inode feature
xfs: bufferhead chains are invalid after end_page_writeback
xfs: allocate log vector buffers outside CIL context lock
libxfs: directory node splitting does not have an extra block
xfs: remove dax code from object file when disabled
xfs: skip dirty pages in ->releasepage()
xfs: remove __arch_pack
xfs: kill xfs_dir2_inou_t
xfs: kill xfs_dir2_sf_off_t
xfs: split direct I/O and DAX path
xfs: direct calls in the direct I/O path
xfs: stop using generic_file_read_iter for direct I/O
xfs: split xfs_file_read_iter into buffered and direct I/O helpers
xfs: remove s_maxbytes enforcement in xfs_file_read_iter
xfs: kill ioflags
xfs: don't pass ioflags around in the ioctl path
xfs: track and serialize in-flight async buffers against unmount
xfs: exclude never-released buffers from buftarg I/O accounting
xfs: don't reset b_retries to 0 on every failure
xfs: remove extraneous buffer flag changes
...
In xfs_finish_page_writeback(), we have a loop that looks like this:
do {
if (off < bvec->bv_offset)
goto next_bh;
if (off > end)
break;
bh->b_end_io(bh, !error);
next_bh:
off += bh->b_size;
} while ((bh = bh->b_this_page) != head);
The b_end_io function is end_buffer_async_write(), which will call
end_page_writeback() once all the buffers have marked as no longer
under IO. This issue here is that the only thing currently
protecting both the bufferhead chain and the page from being
reclaimed is the PageWriteback state held on the page.
While we attempt to limit the loop to just the buffers covered by
the IO, we still read from the buffer size and follow the next
pointer in the bufferhead chain. There is no guarantee that either
of these are valid after the PageWriteback flag has been cleared.
Hence, loops like this are completely unsafe, and result in
use-after-free issues. One such problem was caught by Calvin Owens
with KASAN:
.....
INFO: Freed in 0x103fc80ec age=18446651500051355200 cpu=2165122683 pid=-1
free_buffer_head+0x41/0x90
__slab_free+0x1ed/0x340
kmem_cache_free+0x270/0x300
free_buffer_head+0x41/0x90
try_to_free_buffers+0x171/0x240
xfs_vm_releasepage+0xcb/0x3b0
try_to_release_page+0x106/0x190
shrink_page_list+0x118e/0x1a10
shrink_inactive_list+0x42c/0xdf0
shrink_zone_memcg+0xa09/0xfa0
shrink_zone+0x2c3/0xbc0
.....
Call Trace:
<IRQ> [<ffffffff81e8b8e4>] dump_stack+0x68/0x94
[<ffffffff8153a995>] print_trailer+0x115/0x1a0
[<ffffffff81541174>] object_err+0x34/0x40
[<ffffffff815436e7>] kasan_report_error+0x217/0x530
[<ffffffff81543b33>] __asan_report_load8_noabort+0x43/0x50
[<ffffffff819d651f>] xfs_destroy_ioend+0x3bf/0x4c0
[<ffffffff819d69d4>] xfs_end_bio+0x154/0x220
[<ffffffff81de0c58>] bio_endio+0x158/0x1b0
[<ffffffff81dff61b>] blk_update_request+0x18b/0xb80
[<ffffffff821baf57>] scsi_end_request+0x97/0x5a0
[<ffffffff821c5558>] scsi_io_completion+0x438/0x1690
[<ffffffff821a8d95>] scsi_finish_command+0x375/0x4e0
[<ffffffff821c3940>] scsi_softirq_done+0x280/0x340
Where the access is occuring during IO completion after the buffer
had been freed from direct memory reclaim.
Prevent use-after-free accidents in this end_io processing loop by
pre-calculating the loop conditionals before calling bh->b_end_io().
The loop is already limited to just the bufferheads covered by the
IO in progress, so the offset checks are sufficient to prevent
accessing buffers in the chain after end_page_writeback() has been
called by the the bh->b_end_io() callout.
Yet another example of why Bufferheads Must Die.
cc: <stable@vger.kernel.org> # 4.7
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reported-and-Tested-by: Calvin Owens <calvinowens@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
XFS has had scattered reports of delalloc blocks present at
->releasepage() time. This results in a warning with a stack trace
similar to the following:
...
Call Trace:
[<ffffffffa23c5b8f>] dump_stack+0x63/0x84
[<ffffffffa20837a7>] warn_slowpath_common+0x97/0xe0
[<ffffffffa208380a>] warn_slowpath_null+0x1a/0x20
[<ffffffffa2326caf>] xfs_vm_releasepage+0x10f/0x140
[<ffffffffa218c680>] ? page_mkclean_one+0xd0/0xd0
[<ffffffffa218d3a0>] ? anon_vma_prepare+0x150/0x150
[<ffffffffa21521c2>] try_to_release_page+0x32/0x50
[<ffffffffa2166b2e>] shrink_active_list+0x3ce/0x3e0
[<ffffffffa21671c7>] shrink_lruvec+0x687/0x7d0
[<ffffffffa21673ec>] shrink_zone+0xdc/0x2c0
[<ffffffffa2168539>] kswapd+0x4f9/0x970
[<ffffffffa2168040>] ? mem_cgroup_shrink_node_zone+0x1a0/0x1a0
[<ffffffffa20a0d99>] kthread+0xc9/0xe0
[<ffffffffa20a0cd0>] ? kthread_stop+0x100/0x100
[<ffffffffa26b404f>] ret_from_fork+0x3f/0x70
[<ffffffffa20a0cd0>] ? kthread_stop+0x100/0x100
This occurs because it is possible for shrink_active_list() to send
pages marked dirty to ->releasepage() when certain buffer_head threshold
conditions are met. shrink_active_list() doesn't check the page dirty
state apparently to handle an old ext3 corner case where in some cases
clean pages would not have the dirty bit cleared, thus it is up to the
filesystem to determine how to handle the page.
XFS currently handles the delalloc case properly, but this behavior
makes the warning spurious. Update the XFS ->releasepage() handler to
explicitly skip dirty pages. Retain the existing delalloc/unwritten
checks so we continue to warn if such buffers exist on clean pages when
they shouldn't.
Diagnosed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
We control both the callers and callees of ->direct_IO, so remove the
indirect calls.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Convert XFS to use the new iomap based multipage write path. This involves
implementing the ->iomap_begin and ->iomap_end methods, and switching the
buffered file write, page_mkwrite and xfs_iozero paths to the new iomap
helpers.
With this change __xfs_get_blocks will never be used for buffered writes,
and the code handling them can be removed.
Based on earlier code from Dave Chinner.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Separate the op from the rq_flag_bits and have xfs
set/get the bio using bio_set_op_attrs/bio_op.
Signed-off-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This has callers of submit_bio/submit_bio_wait set the bio->bi_rw
instead of passing it in. This makes that use the same as
generic_make_request and how we set the other bio fields.
Signed-off-by: Mike Christie <mchristi@redhat.com>
Fixed up fs/ext4/crypto.c
Signed-off-by: Jens Axboe <axboe@fb.com>
Changes in this update:
o fixes for mount line parsing, sparse warnings, read-only compat
feature remount behaviour
o allow fast path symlink lookups for inline symlinks.
o attribute listing cleanups
o writeback goes direct to bios rather than indirecting through
bufferheads
o transaction allocation cleanup
o optimised kmem_realloc
o added configurable error handling for metadata write errors,
changed default error handling behaviour from "retry forever" to
"retry until unmount then fail"
o fixed several inode cluster writeback lookup vs reclaim race
conditions
o fixed inode cluster writeback checking wrong inode after lookup
o fixed bugs where struct xfs_inode freeing wasn't actually RCU safe
o cleaned up inode reclaim tagging
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Merge tag 'xfs-for-linus-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs
Pull xfs updates from Dave Chinner:
"A pretty average collection of fixes, cleanups and improvements in
this request.
Summary:
- fixes for mount line parsing, sparse warnings, read-only compat
feature remount behaviour
- allow fast path symlink lookups for inline symlinks.
- attribute listing cleanups
- writeback goes direct to bios rather than indirecting through
bufferheads
- transaction allocation cleanup
- optimised kmem_realloc
- added configurable error handling for metadata write errors,
changed default error handling behaviour from "retry forever" to
"retry until unmount then fail"
- fixed several inode cluster writeback lookup vs reclaim race
conditions
- fixed inode cluster writeback checking wrong inode after lookup
- fixed bugs where struct xfs_inode freeing wasn't actually RCU safe
- cleaned up inode reclaim tagging"
* tag 'xfs-for-linus-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs: (39 commits)
xfs: fix warning in xfs_finish_page_writeback for non-debug builds
xfs: move reclaim tagging functions
xfs: simplify inode reclaim tagging interfaces
xfs: rename variables in xfs_iflush_cluster for clarity
xfs: xfs_iflush_cluster has range issues
xfs: mark reclaimed inodes invalid earlier
xfs: xfs_inode_free() isn't RCU safe
xfs: optimise xfs_iext_destroy
xfs: skip stale inodes in xfs_iflush_cluster
xfs: fix inode validity check in xfs_iflush_cluster
xfs: xfs_iflush_cluster fails to abort on error
xfs: remove xfs_fs_evict_inode()
xfs: add "fail at unmount" error handling configuration
xfs: add configuration handlers for specific errors
xfs: add configuration of error failure speed
xfs: introduce table-based init for error behaviors
xfs: add configurable error support to metadata buffers
xfs: introduce metadata IO error class
xfs: configurable error behavior via sysfs
xfs: buffer ->bi_end_io function requires irq-safe lock
...
Including blkdev_direct_IO and dax_do_io. It has to be ki_pos to actually
work, so eliminate the superflous argument.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Merge xfs_trans_reserve and xfs_trans_alloc into a single function call
that returns a transaction with all the required log and block reservations,
and which allows passing transaction flags directly to avoid the cumbersome
_xfs_trans_alloc interface.
While we're at it we also get rid of the transaction type argument that has
been superflous since we stopped supporting the non-CIL logging mode. The
guts of it will be removed in another patch.
[dchinner: fixed transaction leak in error path in xfs_setattr_nonsize]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This patch implements two closely related changes: First it embeds
a bio the ioend structure so that we don't have to allocate one
separately. Second it uses the block layer bio chaining mechanism
to chain additional bios off this first one if needed instead of
manually accounting for multiple bio completions in the ioend
structure. Together this removes a memory allocation per ioend and
greatly simplifies the ioend setup and I/O completion path.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Completion of an ioend requires us to walk the bufferhead list to
end writback on all the bufferheads. This, in turn, is needed so
that we can end writeback on all the pages we just did IO on.
To remove our dependency on bufferheads in writeback, we need to
turn this around the other way - we need to walk the pages we've
just completed IO on, and then walk the buffers attached to the
pages and complete their IO. In doing this, we remove the
requirement for the ioend to track bufferheads directly.
To enable IO completion to walk all the pages we've submitted IO on,
we need to keep the bios that we used for IO around until the ioend
has been completed. We can do this simply by chaining the bios to
the ioend at completion time, and then walking their pages directly
just before destroying the ioend.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
[hch: changed the xfs_finish_page_writeback calling convention]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Currently adding a buffer to the ioend and then building a bio from
the buffer list are two separate operations. We don't build the bios
and submit them until the ioend is submitted, and this places a
fixed dependency on bufferhead chaining in the ioend.
The first step to removing the bufferhead chaining in the ioend is
on the IO submission side. We can build the bio directly as we add
the buffers to the ioend chain, thereby removing the need for a
latter "buffer-to-bio" submission loop. This allows us to submit
bios on large ioends as soon as we cannot add more data to the bio.
These bios then get captured by the active plug, and hence will be
dispatched as soon as either the plug overflows or we schedule away
from the writeback context. This will reduce submission latency for
large IOs, but will also allow more timely request queue based
writeback blocking when the device becomes congested.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
[hch: various small updates]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Mostly direct substitution with occasional adjustment or removing
outdated comments.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.
This promise never materialized. And unlikely will.
We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.
Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.
Let's stop pretending that pages in page cache are special. They are
not.
The changes are pretty straight-forward:
- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
- page_cache_get() -> get_page();
- page_cache_release() -> put_page();
This patch contains automated changes generated with coccinelle using
script below. For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.
The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.
There are few places in the code where coccinelle didn't reach. I'll
fix them manually in a separate patch. Comments and documentation also
will be addressed with the separate patch.
virtual patch
@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT
@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE
@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK
@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)
@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)
@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change summary:
o error propagation for direct IO failures fixes for both XFS and ext4
o new quota interfaces and XFS implementation for iterating all the quota IDs
in the filesystem
o locking fixes for real-time device extent allocation
o reduction of duplicate information in the xfs and vfs inode, saving roughly
100 bytes of memory per cached inode.
o buffer flag cleanup
o rework of the writepage code to use the generic write clustering mechanisms
o several fixes for inode flag based DAX enablement
o rework of remount option parsing
o compile time verification of on-disk format structure sizes
o delayed allocation reservation overrun fixes
o lots of little error handling fixes
o small memory leak fixes
o enable xfsaild freezing again
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Merge tag 'xfs-for-linus-4.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs
Pull xfs updates from Dave Chinner:
"There's quite a lot in this request, and there's some cross-over with
ext4, dax and quota code due to the nature of the changes being made.
As for the rest of the XFS changes, there are lots of little things
all over the place, which add up to a lot of changes in the end.
The major changes are that we've reduced the size of the struct
xfs_inode by ~100 bytes (gives an inode cache footprint reduction of
>10%), the writepage code now only does a single set of mapping tree
lockups so uses less CPU, delayed allocation reservations won't
overrun under random write loads anymore, and we added compile time
verification for on-disk structure sizes so we find out when a commit
or platform/compiler change breaks the on disk structure as early as
possible.
Change summary:
- error propagation for direct IO failures fixes for both XFS and
ext4
- new quota interfaces and XFS implementation for iterating all the
quota IDs in the filesystem
- locking fixes for real-time device extent allocation
- reduction of duplicate information in the xfs and vfs inode, saving
roughly 100 bytes of memory per cached inode.
- buffer flag cleanup
- rework of the writepage code to use the generic write clustering
mechanisms
- several fixes for inode flag based DAX enablement
- rework of remount option parsing
- compile time verification of on-disk format structure sizes
- delayed allocation reservation overrun fixes
- lots of little error handling fixes
- small memory leak fixes
- enable xfsaild freezing again"
* tag 'xfs-for-linus-4.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs: (66 commits)
xfs: always set rvalp in xfs_dir2_node_trim_free
xfs: ensure committed is initialized in xfs_trans_roll
xfs: borrow indirect blocks from freed extent when available
xfs: refactor delalloc indlen reservation split into helper
xfs: update freeblocks counter after extent deletion
xfs: debug mode forced buffered write failure
xfs: remove impossible condition
xfs: check sizes of XFS on-disk structures at compile time
xfs: ioends require logically contiguous file offsets
xfs: use named array initializers for log item dumping
xfs: fix computation of inode btree maxlevels
xfs: reinitialise per-AG structures if geometry changes during recovery
xfs: remove xfs_trans_get_block_res
xfs: fix up inode32/64 (re)mount handling
xfs: fix format specifier , should be %llx and not %llu
xfs: sanitize remount options
xfs: convert mount option parsing to tokens
xfs: fix two memory leaks in xfs_attr_list.c error paths
xfs: XFS_DIFLAG2_DAX limited by PAGE_SIZE
xfs: dynamically switch modes when XFS_DIFLAG2_DAX is set/cleared
...
Now that migration doesn't clear page->mem_cgroup of live pages anymore,
it's safe to make lock_page_memcg() and the memcg stat functions take
pages, and spare the callers from memcg objects.
[akpm@linux-foundation.org: fix warnings]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These patches tag the page cache radix tree eviction entries with the
memcg an evicted page belonged to, thus making per-cgroup LRU reclaim
work properly and be as adaptive to new cache workingsets as global
reclaim already is.
This should have been part of the original thrash detection patch
series, but was deferred due to the complexity of those patches.
This patch (of 5):
So far the only sites that needed to exclude charge migration to
stabilize page->mem_cgroup have been per-cgroup page statistics, hence
the name mem_cgroup_begin_page_stat(). But per-cgroup thrash detection
will add another site that needs to ensure page->mem_cgroup lifetime.
Rename these locking functions to the more generic lock_page_memcg() and
unlock_page_memcg(). Since charge migration is a cgroup1 feature only,
we might be able to delete it at some point, and these now easy to
identify locking sites along with it.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a DEBUG mode-only sysfs knob to enable forced buffered write
failure. An additional side effect of this mode is brute force killing
of delayed allocation blocks in the range of the write. The latter is
the prime motiviation behind this patch, as userspace test
infrastructure requires a reliable mechanism to create and split
delalloc extents without causing extent conversion.
Certain fallocate operations (i.e., zero range) were used for this in
the past, but the implementations have changed such that delalloc
extents are flushed and converted to real blocks, rendering the test
useless.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
We need to create a new ioend if the current writepage call isn't
logically contiguous with the range contained in the previous ioend.
Hopefully writepage gets called in order of increasing file offset.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Previously calls to dax_writeback_mapping_range() for all DAX filesystems
(ext2, ext4 & xfs) were centralized in filemap_write_and_wait_range().
dax_writeback_mapping_range() needs a struct block_device, and it used
to get that from inode->i_sb->s_bdev. This is correct for normal inodes
mounted on ext2, ext4 and XFS filesystems, but is incorrect for DAX raw
block devices and for XFS real-time files.
Instead, call dax_writeback_mapping_range() directly from the filesystem
->writepages function so that it can supply us with a valid block
device. This also fixes DAX code to properly flush caches in response
to sync(2).
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
dax_clear_blocks() needs a valid struct block_device and previously it
was using inode->i_sb->s_bdev in all cases. This is correct for normal
inodes on mounted ext2, ext4 and XFS filesystems, but is incorrect for
DAX raw block devices and for XFS real-time devices.
Instead, rename dax_clear_blocks() to dax_clear_sectors(), and change
its arguments to take a bdev and a sector instead of an inode and a
block. This better reflects what the function does, and it allows the
filesystem and raw block device code to pass in an appropriate struct
block_device.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently we can build a long ioend chain during ->writepages that
gets attached to the writepage context. IO submission only then
occurs when we finish all the writepage processing. This means we
can have many ioends allocated and pending, and this violates the
mempool guarantees that we need to give about forwards progress.
i.e. we really should only have one ioend being built at a time,
otherwise we may drain the mempool trying to allocate a new ioend
and that blocks submission, completion and freeing of ioends that
are already in progress.
To prevent this situation from happening, we need to submit ioends
for IO as soon as they are ready for dispatch rather than queuing
them for later submission. This means the ioends have bios built
immediately and they get queued on any plug that is current active.
Hence if we schedule away from writeback, the ioends that have been
built will make forwards progress due to the plug flushing on
context switch. This will also prevent context switches from
creating unnecessary IO submission latency.
We can't completely avoid having nested IO allocation - when we have
a block size smaller than a page size, we still need to hold the
ioend submission until after we have marked the current page dirty.
Hence we may need multiple ioends to be held while the current page
is completely mapped and made ready for IO dispatch. We cannot avoid
this problem - the current code already has this ioend chaining
within a page so we can mostly ignore that it occurs.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
