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d05a2b4cd9
linux/fs/btrfs
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Filipe Manana d05a2b4cd9 Btrfs: fix race that makes btrfs_lookup_extent_info miss skinny extent items 
We have a race that can lead us to miss skinny extent items in the function
btrfs_lookup_extent_info() when the skinny metadata feature is enabled.
So basically the sequence of steps is:

1) We search in the extent tree for the skinny extent, which returns > 0
   (not found);

2) We check the previous item in the returned leaf for a non-skinny extent,
   and we don't find it;

3) Because we didn't find the non-skinny extent in step 2), we release our
   path to search the extent tree again, but this time for a non-skinny
   extent key;

4) Right after we released our path in step 3), a skinny extent was inserted
   in the extent tree (delayed refs were run) - our second extent tree search
   will miss it, because it's not looking for a skinny extent;

5) After the second search returned (with ret > 0), we look for any delayed
   ref for our extent's bytenr (and we do it while holding a read lock on the
   leaf), but we won't find any, as such delayed ref had just run and completed
   after we released out path in step 3) before doing the second search.

Fix this by removing completely the path release and re-search logic. This is
safe, because if we seach for a metadata item and we don't find it, we have the
guarantee that the returned leaf is the one where the item would be inserted,
and so path->slots[0] > 0 and path->slots[0] - 1 must be the slot where the
non-skinny extent item is if it exists. The only case where path->slots[0] is
zero is when there are no smaller keys in the tree (i.e. no left siblings for
our leaf), in which case the re-search logic isn't needed as well.

This race has been present since the introduction of skinny metadata (change
3173a18f70).

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
2014-10-28 13:59:54 -07:00
..
tests Btrfs: remove empty block groups automatically 2014-09-22 17:13:21 -07:00
acl.c btrfs: remove useless ACL check 2014-06-09 17:20:42 -07:00
async-thread.c btrfs: remove unlikely from NULL checks 2014-10-02 16:06:19 +02:00
async-thread.h Btrfs: implement repair function when direct read fails 2014-09-17 13:39:01 -07:00
backref.c btrfs: remove parameter blocksize from read_tree_block 2014-10-02 17:14:50 +02:00
backref.h Btrfs: make fiemap not blow when you have lots of snapshots 2014-09-17 13:38:24 -07:00
btrfs_inode.h Btrfs: be aware of btree inode write errors to avoid fs corruption 2014-10-03 16:14:59 -07:00
check-integrity.c Btrfs: fix wrong disk size when writing super blocks 2014-09-17 13:38:33 -07:00
check-integrity.h block: submit_bio_wait() conversions 2013-11-24 16:33:41 -07:00
compression.c btrfs: use enum for wq endio metadata type 2014-10-02 17:30:28 +02:00
compression.h btrfs: make static code static & remove dead code 2013-05-06 15:55:23 -04:00
ctree.c Merge branch 'cleanup/blocksize-diet-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus 2014-10-04 09:57:14 -07:00
ctree.h Btrfs: fix invalid leaf slot access in btrfs_lookup_extent() 2014-10-27 13:16:52 -07:00
delayed-inode.c btrfs: kill the key type accessor helpers 2014-09-17 13:37:12 -07:00
delayed-inode.h Btrfs: introduce the delayed inode ref deletion for the single link inode 2014-01-28 13:20:09 -08:00
delayed-ref.c Btrfs: rework qgroup accounting 2014-06-09 17:20:48 -07:00
delayed-ref.h Btrfs: rework qgroup accounting 2014-06-09 17:20:48 -07:00
dev-replace.c Btrfs: make the logic of source device removing more clear 2014-09-17 13:38:46 -07:00
dev-replace.h
dir-item.c btrfs: kill the key type accessor helpers 2014-09-17 13:37:12 -07:00
disk-io.c btrfs: use macro accessors in superblock validation checks 2014-10-27 13:16:52 -07:00
disk-io.h Merge branch 'cleanup/blocksize-diet-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus 2014-10-04 09:57:14 -07:00
export.c btrfs: kill the key type accessor helpers 2014-09-17 13:37:12 -07:00
export.h
extent_io.c Merge branch 'cleanup/misc-for-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus 2014-10-04 09:56:45 -07:00
extent_io.h Btrfs: fix compiles when CONFIG_BTRFS_FS_RUN_SANITY_TESTS is off 2014-10-07 13:24:20 -07:00
extent_map.c Btrfs: fix NULL pointer crash when running balance and scrub concurrently 2014-06-19 14:20:55 -07:00
extent_map.h Btrfs: fix NULL pointer crash when running balance and scrub concurrently 2014-06-19 14:20:55 -07:00
extent-tree.c Btrfs: fix race that makes btrfs_lookup_extent_info miss skinny extent items 2014-10-28 13:59:54 -07:00
file-item.c Btrfs: load checksum data once when submitting a direct read io 2014-09-17 13:38:50 -07:00
file.c btrfs: remove unlikely from data-dependent branches and slow paths 2014-10-02 16:15:21 +02:00
free-space-cache.c Btrfs: improve free space cache management and space allocation 2014-09-17 13:38:13 -07:00
free-space-cache.h Btrfs: remove path arg from btrfs_truncate_free_space_cache 2013-11-11 21:51:33 -05:00
hash.c btrfs: use PTR_ERR_OR_ZERO 2014-09-17 13:37:29 -07:00
hash.h Btrfs: fix btrfs boot when compiled as built-in 2014-01-28 13:20:31 -08:00
inode-item.c btrfs: kill the key type accessor helpers 2014-09-17 13:37:12 -07:00
inode-map.c btrfs: cleanup ino cache members of btrfs_root 2014-09-17 13:37:09 -07:00
inode-map.h
inode.c Revert "Btrfs: race free update of commit root for ro snapshots" 2014-10-17 02:40:59 -07:00
ioctl.c Revert "Btrfs: race free update of commit root for ro snapshots" 2014-10-17 02:40:59 -07:00
Kconfig Btrfs: fix btrfs boot when compiled as built-in 2014-01-28 13:20:31 -08:00
locking.c Btrfs: fix deadlocks with trylock on tree nodes 2014-06-19 14:19:55 -07:00
locking.h Btrfs: remove btrfs_try_spin_lock 2013-03-14 14:57:10 -04:00
lzo.c btrfs: use DIV_ROUND_UP instead of open-coded variants 2014-09-17 13:37:17 -07:00
Makefile Btrfs: add sanity tests for new qgroup accounting code 2014-06-09 17:20:49 -07:00
math.h
ordered-data.c Btrfs: fix task hang under heavy compressed write 2014-08-24 07:17:02 -07:00
ordered-data.h btrfs: disable strict file flushes for renames and truncates 2014-08-15 07:43:42 -07:00
orphan.c btrfs: kill the key type accessor helpers 2014-09-17 13:37:12 -07:00
print-tree.c btrfs: remove parameter blocksize from read_tree_block 2014-10-02 17:14:50 +02:00
print-tree.h btrfs: make static code static & remove dead code 2013-05-06 15:55:23 -04:00
props.c Btrfs: add support for inode properties 2014-01-28 13:20:24 -08:00
props.h Btrfs: add support for inode properties 2014-01-28 13:20:24 -08:00
qgroup.c btrfs: move checks for DUMMY_ROOT into a helper 2014-10-02 17:30:33 +02:00
qgroup.h btrfs: qgroup: account shared subtrees during snapshot delete 2014-08-15 07:43:14 -07:00
raid56.c btrfs: use DIV_ROUND_UP instead of open-coded variants 2014-09-17 13:37:17 -07:00
raid56.h Btrfs: RAID5 and RAID6 2013-02-01 14:24:23 -05:00
rcu-string.h
reada.c btrfs: use nodesize everywhere, kill leafsize 2014-09-17 13:37:14 -07:00
relocation.c Merge branch 'cleanup/blocksize-diet-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus 2014-10-04 09:57:14 -07:00
root-tree.c Btrfs: use bitfield instead of integer data type for the some variants in btrfs_root 2014-06-09 17:20:40 -07:00
scrub.c btrfs: remove unused members from struct scrub_warning 2014-10-02 17:30:30 +02:00
send.c Merge branch 'cleanup/misc-for-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus 2014-10-04 09:56:45 -07:00
send.h btrfs: make static code static & remove dead code 2013-05-06 15:55:23 -04:00
struct-funcs.c
super.c Btrfs: properly clean up btrfs_end_io_wq_cache 2014-10-27 13:16:53 -07:00
sysfs.c btrfs: sysfs label interface should check for read only FS 2014-09-17 13:38:01 -07:00
sysfs.h btrfs: code optimize: BTRFS_ATTR_RW could set the mode 2014-09-17 13:37:59 -07:00
transaction.c Merge branch 'remove-unlikely' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus 2014-10-04 09:57:44 -07:00
transaction.h btrfs: hide typecast to definition of BTRFS_SEND_TRANS_STUB 2014-10-02 17:30:31 +02:00
tree-defrag.c Btrfs: use bitfield instead of integer data type for the some variants in btrfs_root 2014-06-09 17:20:40 -07:00
tree-log.c Btrfs: fix invalid leaf slot access in btrfs_lookup_extent() 2014-10-27 13:16:52 -07:00
tree-log.h Btrfs: fix data corruption after fast fsync and writeback error 2014-09-19 06:57:51 -07:00
ulist.c Btrfs: do not export ulist functions 2014-01-29 07:06:27 -08:00
ulist.h Btrfs: Fix memory corruption by ulist_add_merge() on 32bit arch 2014-08-15 07:43:19 -07:00
uuid-tree.c Btrfs: make btrfs_search_forward return with nodes unlocked 2014-09-17 13:38:02 -07:00
volumes.c Btrfs: fix compilation errors under DEBUG 2014-10-03 16:14:58 -07:00
volumes.h Btrfs: remove empty block groups automatically 2014-09-22 17:13:21 -07:00
xattr.c btrfs: kill the key type accessor helpers 2014-09-17 13:37:12 -07:00
xattr.h btrfs: use generic posix ACL infrastructure 2014-01-25 23:58:18 -05:00
zlib.c btrfs compression: merge inflate and deflate z_streams 2014-09-17 13:37:33 -07:00