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7f458a3873
linux/fs/btrfs
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Filipe Manana 7f458a3873 btrfs: fix race when defragmenting leads to unnecessary IO 
When defragmenting we skip ranges that have holes or inline extents, so that
we don't do unnecessary IO and waste space. We do this check when calling
should_defrag_range() at btrfs_defrag_file(). However we do it without
holding the inode's lock. The reason we do it like this is to avoid
blocking other tasks for too long, that possibly want to operate on other
file ranges, since after the call to should_defrag_range() and before
locking the inode, we trigger a synchronous page cache readahead. However
before we were able to lock the inode, some other task might have punched
a hole in our range, or we may now have an inline extent there, in which
case we should not set the range for defrag anymore since that would cause
unnecessary IO and make us waste space (i.e. allocating extents to contain
zeros for a hole).

So after we locked the inode and the range in the iotree, check again if
we have holes or an inline extent, and if we do, just skip the range.

I hit this while testing my next patch that fixes races when updating an
inode's number of bytes (subject "btrfs: update the number of bytes used
by an inode atomically"), and it depends on this change in order to work
correctly. Alternatively I could rework that other patch to detect holes
and flag their range with the 'new delalloc' bit, but this itself fixes
an efficiency problem due a race that from a functional point of view is
not harmful (it could be triggered with btrfs/062 from fstests).

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-08 15:54:08 +01:00
..
tests btrfs: load free space cache into a temporary ctl 2020-12-08 15:54:03 +01:00
acl.c
async-thread.c Btrfs: fix crash during unmount due to race with delayed inode workers 2020-03-23 17:01:51 +01:00
async-thread.h Btrfs: fix crash during unmount due to race with delayed inode workers 2020-03-23 17:01:51 +01:00
backref.c btrfs: pass root owner to read_tree_block 2020-12-08 15:54:07 +01:00
backref.h btrfs: rename BTRFS_ROOT_REF_COWS to BTRFS_ROOT_SHAREABLE 2020-05-25 11:25:35 +02:00
block-group.c btrfs: protect fs_info->caching_block_groups by block_group_cache_lock 2020-12-08 15:54:03 +01:00
block-group.h btrfs: load free space cache asynchronously 2020-12-08 15:54:03 +01:00
block-rsv.c btrfs: introduce mount option rescue=ignorebadroots 2020-12-08 15:53:41 +01:00
block-rsv.h btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
btrfs_inode.h btrfs: switch cached fs_info::csum_size from u16 to u32 2020-12-08 15:53:59 +01:00
check-integrity.c btrfs: check integrity: remove local copy of csum_size 2020-12-08 15:54:01 +01:00
check-integrity.h btrfs: remove btrfsic_submit_bh() 2020-03-23 17:01:39 +01:00
compression.c btrfs: remove unnecessary local variables for checksum size 2020-12-08 15:54:00 +01:00
compression.h btrfs: compression: move declarations to header 2020-10-07 12:06:55 +02:00
ctree.c btrfs: pass root owner to read_tree_block 2020-12-08 15:54:07 +01:00
ctree.h btrfs: refactor btrfs_drop_extents() to make it easier to extend 2020-12-08 15:54:08 +01:00
delalloc-space.c btrfs: add btrfs_reserve_data_bytes and use it 2020-10-07 12:06:52 +02:00
delalloc-space.h btrfs: make btrfs_delalloc_reserve_space take btrfs_inode 2020-07-27 12:55:36 +02:00
delayed-inode.c btrfs: locking: rip out path->leave_spinning 2020-12-08 15:54:02 +01:00
delayed-inode.h btrfs: delayed-inode: Replace zero-length array with flexible-array member 2020-03-23 17:01:53 +01:00
delayed-ref.c btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
delayed-ref.h btrfs: migrate the delayed refs rsv code 2019-07-04 17:26:17 +02:00
dev-replace.c btrfs: dev-replace: fail mount if we don't have replace item with target device 2020-11-05 13:03:31 +01:00
dev-replace.h btrfs: add __pure attribute to functions 2019-11-18 12:46:52 +01:00
dir-item.c btrfs: locking: rip out path->leave_spinning 2020-12-08 15:54:02 +01:00
discard.c btrfs: don't miss async discards after scheduled work override 2020-12-08 15:54:05 +01:00
discard.h btrfs: cleanup btrfs_discard_update_discardable usage 2020-12-08 15:54:02 +01:00
disk-io.c btrfs: set the lockdep class for extent buffers on creation 2020-12-08 15:54:07 +01:00
disk-io.h btrfs: pass the owner_root and level to alloc_extent_buffer 2020-12-08 15:54:07 +01:00
export.c btrfs: locking: rip out path->leave_spinning 2020-12-08 15:54:02 +01:00
export.h btrfs: export helpers for subvolume name/id resolution 2020-03-23 17:01:42 +01:00
extent_io.c btrfs: set the lockdep class for extent buffers on creation 2020-12-08 15:54:07 +01:00
extent_io.h btrfs: pass the owner_root and level to alloc_extent_buffer 2020-12-08 15:54:07 +01:00
extent_map.c Btrfs: fix race between using extent maps and merging them 2020-02-12 17:16:46 +01:00
extent_map.h btrfs: remove extent_map::bdev 2019-11-18 23:43:44 +01:00
extent-io-tree.h btrfs: sink the failed_start parameter to set_extent_bit 2020-12-08 15:53:54 +01:00
extent-tree.c btrfs: set the lockdep class for extent buffers on creation 2020-12-08 15:54:07 +01:00
file-item.c btrfs: locking: rip out path->leave_spinning 2020-12-08 15:54:02 +01:00
file.c btrfs: refactor btrfs_drop_extents() to make it easier to extend 2020-12-08 15:54:08 +01:00
free-space-cache.c btrfs: load free space cache into a temporary ctl 2020-12-08 15:54:03 +01:00
free-space-cache.h btrfs: load free space cache into a temporary ctl 2020-12-08 15:54:03 +01:00
free-space-tree.c btrfs: locking: rip out path->leave_spinning 2020-12-08 15:54:02 +01:00
free-space-tree.h btrfs: rename btrfs_block_group_cache 2019-11-18 17:51:51 +01:00
inode-item.c btrfs: locking: rip out path->leave_spinning 2020-12-08 15:54:02 +01:00
inode-map.c btrfs: make btrfs_delalloc_reserve_space take btrfs_inode 2020-07-27 12:55:36 +02:00
inode-map.h
inode.c btrfs: refactor btrfs_drop_extents() to make it easier to extend 2020-12-08 15:54:08 +01:00
ioctl.c btrfs: fix race when defragmenting leads to unnecessary IO 2020-12-08 15:54:08 +01:00
Kconfig btrfs: switch to iomap for direct IO 2020-10-07 12:06:57 +02:00
locking.c btrfs: locking: remove all the blocking helpers 2020-12-08 15:54:01 +01:00
locking.h btrfs: locking: remove all the blocking helpers 2020-12-08 15:54:01 +01:00
lzo.c btrfs: compression: inline free_workspace 2019-11-18 12:46:59 +01:00
Makefile Btrfs: move all reflink implementation code into its own file 2020-03-23 17:01:54 +01:00
misc.h btrfs: rename tree_entry to rb_simple_node and export it 2020-05-25 11:25:19 +02:00
ordered-data.c btrfs: switch cached fs_info::csum_size from u16 to u32 2020-12-08 15:53:59 +01:00
ordered-data.h btrfs: remove unnecessary local variables for checksum size 2020-12-08 15:54:00 +01:00
orphan.c
print-tree.c btrfs: pass root owner to read_tree_block 2020-12-08 15:54:07 +01:00
print-tree.h btrfs: pretty print leaked root name 2020-10-07 12:12:20 +02:00
props.c btrfs: simplify iget helpers 2020-05-25 11:25:37 +02:00
props.h btrfs: delete unused function btrfs_set_prop_trans 2019-04-29 19:02:54 +02:00
qgroup.c btrfs: pass root owner to read_tree_block 2020-12-08 15:54:07 +01:00
qgroup.h btrfs: qgroup: export qgroups in sysfs 2020-07-27 12:55:37 +02:00
raid56.c btrfs: raid56: remove out label in __raid56_parity_recover 2020-07-27 12:55:44 +02:00
raid56.h btrfs: constify map parameter for nr_parity_stripes and nr_data_stripes 2019-07-01 13:34:58 +02:00
rcu-string.h btrfs: rcu-string: Replace zero-length array with flexible-array member 2020-03-23 17:01:53 +01:00
reada.c btrfs: pass the owner_root and level to alloc_extent_buffer 2020-12-08 15:54:07 +01:00
ref-verify.c btrfs: use btrfs_read_node_slot in walk_down_tree 2020-12-08 15:54:06 +01:00
ref-verify.h
reflink.c btrfs: refactor btrfs_drop_extents() to make it easier to extend 2020-12-08 15:54:08 +01:00
reflink.h Btrfs: move all reflink implementation code into its own file 2020-03-23 17:01:54 +01:00
relocation.c btrfs: pass the owner_root and level to alloc_extent_buffer 2020-12-08 15:54:07 +01:00
root-tree.c btrfs: qgroup: fix qgroup meta rsv leak for subvolume operations 2020-10-07 12:12:13 +02:00
scrub.c btrfs: scrub: refactor scrub_find_csum() 2020-12-08 15:54:05 +01:00
send.c btrfs: send: use helpers to access root_item::ctransid 2020-12-08 15:53:51 +01:00
send.h btrfs: send: avoid copying file data 2020-10-07 12:13:17 +02:00
space-info.c btrfs: kill the RCU protection for fs_info->space_info 2020-10-07 12:13:19 +02:00
space-info.h btrfs: add btrfs_reserve_data_bytes and use it 2020-10-07 12:06:52 +02:00
struct-funcs.c btrfs: use unaligned helpers for stack and header set/get helpers 2020-10-07 12:13:23 +02:00
super.c btrfs: locking: rip out path->leave_spinning 2020-12-08 15:54:02 +01:00
sysfs.c btrfs: discard: reschedule work after sysfs param update 2020-12-08 15:54:05 +01:00
sysfs.h btrfs: split and refactor btrfs_sysfs_remove_devices_dir 2020-10-07 12:12:21 +02:00
transaction.c btrfs: protect fs_info->caching_block_groups by block_group_cache_lock 2020-12-08 15:54:03 +01:00
transaction.h btrfs: remove dio iomap DSYNC workaround 2020-12-08 15:53:49 +01:00
tree-checker.c btrfs: switch cached fs_info::csum_size from u16 to u32 2020-12-08 15:53:59 +01:00
tree-checker.h
tree-defrag.c btrfs: locking: remove all the blocking helpers 2020-12-08 15:54:01 +01:00
tree-log.c btrfs: refactor btrfs_drop_extents() to make it easier to extend 2020-12-08 15:54:08 +01:00
tree-log.h btrfs: make fast fsyncs wait only for writeback 2020-10-07 12:06:56 +02:00
ulist.c
ulist.h
uuid-tree.c btrfs: remove unnecessary casts in printk 2020-12-08 15:53:52 +01:00
volumes.c btrfs: set the lockdep class for extent buffers on creation 2020-12-08 15:54:07 +01:00
volumes.h btrfs: create read policy framework 2020-12-08 15:53:44 +01:00
xattr.c Btrfs: fix failure to persist compression property xattr deletion on fsync 2019-06-17 16:37:17 +02:00
xattr.h
zlib.c btrfs: use larger zlib buffer for s390 hardware compression 2020-01-31 10:30:40 -08:00
zstd.c btrfs: compression: inline free_workspace 2019-11-18 12:46:59 +01:00