alistair23-linux/fs/btrfs
Omar Sandoval 8e2bd3b7fa Btrfs: deal with existing encompassing extent map in btrfs_get_extent()
My QEMU VM was seeing inexplicable I/O errors that I tracked down to
errors coming from the qcow2 virtual drive in the host system. The qcow2
file is a nocow file on my Btrfs drive, which QEMU opens with O_DIRECT.
Every once in awhile, pread() or pwrite() would return EEXIST, which
makes no sense. This turned out to be a bug in btrfs_get_extent().

Commit 8dff9c8534 ("Btrfs: deal with duplciates during extent_map
insertion in btrfs_get_extent") fixed a case in btrfs_get_extent() where
two threads race on adding the same extent map to an inode's extent map
tree. However, if the added em is merged with an adjacent em in the
extent tree, then we'll end up with an existing extent that is not
identical to but instead encompasses the extent we tried to add. When we
call merge_extent_mapping() to find the nonoverlapping part of the new
em, the arithmetic overflows because there is no such thing. We then end
up trying to add a bogus em to the em_tree, which results in a EEXIST
that can bubble all the way up to userspace.

Fix it by extending the identical extent map special case.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2016-11-30 13:45:14 +01:00
..
tests Merge branch 'fst-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.9 2016-10-12 13:16:00 -07:00
acl.c posix_acl: Clear SGID bit when setting file permissions 2016-09-22 10:55:32 +02:00
async-thread.c btrfs: plumb fs_info into btrfs_work 2016-07-26 13:53:15 +02:00
async-thread.h btrfs: plumb fs_info into btrfs_work 2016-07-26 13:53:15 +02:00
backref.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
backref.h btrfs: cleanup, remove inode_item_info helper 2015-01-14 19:23:47 +01:00
btrfs_inode.h Btrfs: add a flags field to btrfs_fs_info 2016-09-26 17:59:49 +02:00
check-integrity.c btrfs: don't abuse REQ_OP_* flags for btrfs_map_block 2016-11-29 14:10:38 +01:00
check-integrity.h fs: have submit_bh users pass in op and flags separately 2016-06-07 13:41:38 -06:00
compression.c btrfs: assign error values to the correct bio structs 2016-10-17 14:16:14 -07:00
compression.h btrfs: move btrfs_compression_type to compression.h 2016-03-11 17:12:46 +01:00
ctree.c Btrfs: remove unnecessary btrfs_mark_buffer_dirty in split_leaf 2016-09-26 19:50:44 +02:00
ctree.h btrfs: add necessary comments about tickets_id 2016-11-30 13:45:14 +01:00
dedupe.h btrfs: expand cow_file_range() to support in-band dedup and subpage-blocksize 2016-07-26 13:52:25 +02:00
delayed-inode.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
delayed-inode.h Btrfs: fix ->iterate_shared() by upgrading i_rwsem for delayed nodes 2016-06-25 06:20:10 -07:00
delayed-ref.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
delayed-ref.h Btrfs: remove unused function btrfs_add_delayed_qgroup_reserve() 2016-08-03 11:02:51 +01:00
dev-replace.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
dev-replace.h btrfs: refactor btrfs_dev_replace_start for reuse 2016-04-28 10:59:13 +02:00
dir-item.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
disk-io.c Merge branch 'fst-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.9 2016-10-12 13:16:00 -07:00
disk-io.h Btrfs: fix memory leak of block group cache 2016-09-26 17:59:49 +02:00
export.c BTRFS: support NFSv2 export 2015-10-06 06:55:23 -07:00
export.h
extent-tree.c btrfs: cleanup: use already calculated value in btrfs_should_throttle_delayed_refs() 2016-11-29 14:10:38 +01:00
extent_io.c btrfs: don't abuse REQ_OP_* flags for btrfs_map_block 2016-11-29 14:10:38 +01:00
extent_io.h Merge branch 'fst-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.9 2016-10-12 13:16:00 -07:00
extent_map.c btrfs: Fix slab accounting flags 2016-07-26 13:52:25 +02:00
extent_map.h btrfs: cleanup, stop casting for extent_map->lookup everywhere 2016-01-15 19:22:28 +01:00
file-item.c Btrfs: fix __MAX_CSUM_ITEMS 2016-08-03 14:08:37 -07:00
file.c Merge branch 'for-linus-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2016-10-11 11:23:06 -07:00
free-space-cache.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
free-space-cache.h btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
free-space-tree.c Merge branch 'fst-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.9 2016-10-12 13:16:00 -07:00
free-space-tree.h Btrfs: implement the free space B-tree 2015-12-17 12:16:47 -08:00
hash.c btrfs: advertise which crc32c implementation is being used at module load 2016-06-06 14:08:28 +02:00
hash.h btrfs: advertise which crc32c implementation is being used at module load 2016-06-06 14:08:28 +02:00
inode-item.c btrfs: rename btrfs_std_error to btrfs_handle_fs_error 2016-04-28 10:36:54 +02:00
inode-map.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
inode-map.h Btrfs: Initialize btrfs_root->highest_objectid when loading tree root and subvolume roots 2016-01-15 19:25:02 +01:00
inode.c Btrfs: deal with existing encompassing extent map in btrfs_get_extent() 2016-11-30 13:45:14 +01:00
ioctl.c Merge branch 'for-4.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux 2016-11-04 20:08:16 -07:00
Kconfig rcu: Make SRCU optional by using CONFIG_SRCU 2015-01-06 11:04:29 -08:00
locking.c btrfs: cleanup, remove stray return statements 2016-01-07 14:30:52 +01:00
locking.h btrfs: fix lockups from btrfs_clear_path_blocking 2014-11-19 10:34:35 -08:00
lzo.c btrfs: convert printk(KERN_* to use pr_* calls 2016-09-26 18:08:44 +02:00
Makefile Btrfs: add free space tree sanity tests 2015-12-17 12:16:47 -08:00
math.h btrfs: cleanup 64bit/32bit divs, compile time constants 2015-03-03 17:23:57 +01:00
ordered-data.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
ordered-data.h Btrfs: fix race setting block group readonly during device replace 2016-05-30 12:58:21 +01:00
orphan.c btrfs: kill the key type accessor helpers 2014-09-17 13:37:12 -07:00
print-tree.c btrfs: convert printk(KERN_* to use pr_* calls 2016-09-26 18:08:44 +02:00
print-tree.h
props.c btrfs: simpilify btrfs_subvol_inherit_props 2016-07-26 13:54:22 +02:00
props.h
qgroup.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
qgroup.h btrfs: qgroup: Refactor btrfs_qgroup_insert_dirty_extent() 2016-08-25 03:58:21 -07:00
raid56.c Btrfs: remove BUG() in raid56 2016-09-26 17:59:49 +02:00
raid56.h Btrfs: add RAID 5/6 BTRFS_RBIO_REBUILD_MISSING operation 2015-08-09 07:34:26 -07:00
rcu-string.h
reada.c btrfs: don't abuse REQ_OP_* flags for btrfs_map_block 2016-11-29 14:10:38 +01:00
relocation.c Btrfs: kill BUG_ON in do_relocation 2016-10-17 15:48:40 +02:00
root-tree.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
scrub.c btrfs: don't abuse REQ_OP_* flags for btrfs_map_block 2016-11-29 14:10:38 +01:00
send.c Merge branch 'for-linus-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2016-10-28 10:07:35 -07:00
send.h Btrfs: use linux/sizes.h to represent constants 2016-01-07 14:38:02 +01:00
struct-funcs.c btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
super.c btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
sysfs.c btrfs: convert printk(KERN_* to use pr_* calls 2016-09-26 18:08:44 +02:00
sysfs.h btrfs: sysfs: introduce helper for syncing bits with sysfs files 2016-01-21 18:50:40 +01:00
transaction.c Merge branch 'for-linus-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2016-10-11 11:23:06 -07:00
transaction.h btrfs: convert pr_* to btrfs_* where possible 2016-09-26 19:37:04 +02:00
tree-defrag.c Btrfs: fix locking bugs when defragging leaves 2015-12-18 02:51:32 +00:00
tree-log.c Merge branch 'for-linus-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2016-10-28 10:07:35 -07:00
tree-log.h Btrfs: fix lockdep warning on deadlock against an inode's log mutex 2016-08-25 03:58:32 -07:00
ulist.c btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
ulist.h btrfs: ulist: Add ulist_del() function. 2015-06-10 09:26:17 -07:00
uuid-tree.c btrfs: unsplit printed strings 2016-09-26 18:08:44 +02:00
volumes.c btrfs: don't abuse REQ_OP_* flags for btrfs_map_block 2016-11-29 14:10:38 +01:00
volumes.h btrfs: don't abuse REQ_OP_* flags for btrfs_map_block 2016-11-29 14:10:38 +01:00
xattr.c fs: Replace current_fs_time() with current_time() 2016-09-27 21:06:22 -04:00
xattr.h btrfs: Switch to generic xattr handlers 2016-05-17 19:17:09 -04:00
zlib.c btrfs: convert printk(KERN_* to use pr_* calls 2016-09-26 18:08:44 +02:00