android_kernel_oneplus_msm8998/fs/btrfs
Robbie Ko 3109615b52 Btrfs: send, fix failure to rename top level inode due to name collision
[ Upstream commit 4dd9920d991745c4a16f53a8f615f706fbe4b3f7 ]

Under certain situations, an incremental send operation can fail due to a
premature attempt to create a new top level inode (a direct child of the
subvolume/snapshot root) whose name collides with another inode that was
removed from the send snapshot.

Consider the following example scenario.

Parent snapshot:

  .                 (ino 256, gen 8)
  |---- a1/         (ino 257, gen 9)
  |---- a2/         (ino 258, gen 9)

Send snapshot:

  .                 (ino 256, gen 3)
  |---- a2/         (ino 257, gen 7)

In this scenario, when receiving the incremental send stream, the btrfs
receive command fails like this (ran in verbose mode, -vv argument):

  rmdir a1
  mkfile o257-7-0
  rename o257-7-0 -> a2
  ERROR: rename o257-7-0 -> a2 failed: Is a directory

What happens when computing the incremental send stream is:

1) An operation to remove the directory with inode number 257 and
   generation 9 is issued.

2) An operation to create the inode with number 257 and generation 7 is
   issued. This creates the inode with an orphanized name of "o257-7-0".

3) An operation rename the new inode 257 to its final name, "a2", is
   issued. This is incorrect because inode 258, which has the same name
   and it's a child of the same parent (root inode 256), was not yet
   processed and therefore no rmdir operation for it was yet issued.
   The rename operation is issued because we fail to detect that the
   name of the new inode 257 collides with inode 258, because their
   parent, a subvolume/snapshot root (inode 256) has a different
   generation in both snapshots.

So fix this by ignoring the generation value of a parent directory that
matches a root inode (number 256) when we are checking if the name of the
inode currently being processed collides with the name of some other
inode that was not yet processed.

We can achieve this scenario of different inodes with the same number but
different generation values either by mounting a filesystem with the inode
cache option (-o inode_cache) or by creating and sending snapshots across
different filesystems, like in the following example:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt
  $ mkdir /mnt/a1
  $ mkdir /mnt/a2
  $ btrfs subvolume snapshot -r /mnt /mnt/snap1
  $ btrfs send /mnt/snap1 -f /tmp/1.snap
  $ umount /mnt

  $ mkfs.btrfs -f /dev/sdc
  $ mount /dev/sdc /mnt
  $ touch /mnt/a2
  $ btrfs subvolume snapshot -r /mnt /mnt/snap2
  $ btrfs receive /mnt -f /tmp/1.snap
  # Take note that once the filesystem is created, its current
  # generation has value 7 so the inode from the second snapshot has
  # a generation value of 7. And after receiving the first snapshot
  # the filesystem is at a generation value of 10, because the call to
  # create the second snapshot bumps the generation to 8 (the snapshot
  # creation ioctl does a transaction commit), the receive command calls
  # the snapshot creation ioctl to create the first snapshot, which bumps
  # the filesystem's generation to 9, and finally when the receive
  # operation finishes it calls an ioctl to transition the first snapshot
  # (snap1) from RW mode to RO mode, which does another transaction commit
  # and bumps the filesystem's generation to 10.
  $ rm -f /tmp/1.snap
  $ btrfs send /mnt/snap1 -f /tmp/1.snap
  $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/2.snap
  $ umount /mnt

  $ mkfs.btrfs -f /dev/sdd
  $ mount /dev/sdd /mnt
  $ btrfs receive /mnt /tmp/1.snap
  # Receive of snapshot snap2 used to fail.
  $ btrfs receive /mnt /tmp/2.snap

Signed-off-by: Robbie Ko <robbieko@synology.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
[Rewrote changelog to be more precise and clear]
Signed-off-by: Filipe Manana <fdmanana@suse.com>

Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-10-21 17:09:04 +02:00
..
tests Btrfs: tests: checking for NULL instead of IS_ERR() 2015-11-25 05:19:50 -08:00
acl.c posix_acl: Clear SGID bit when setting file permissions 2016-10-31 04:13:58 -06:00
async-thread.c btrfs: limit async_work allocation and worker func duration 2017-01-06 11:16:06 +01:00
async-thread.h btrfs: limit async_work allocation and worker func duration 2017-01-06 11:16:06 +01:00
backref.c Btrfs: fix hang on extent buffer lock caused by the inode_paths ioctl 2016-02-25 12:01:15 -08:00
backref.h
btrfs_inode.h Btrfs: Direct I/O: Fix space accounting 2015-09-21 13:47:55 -07:00
check-integrity.c Merge branch 'cleanups/for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.4 2015-10-21 18:21:40 -07:00
check-integrity.h
compression.c btrfs: assign error values to the correct bio structs 2016-10-22 12:26:54 +02:00
compression.h
ctree.c btrfs: account for non-CoW'd blocks in btrfs_abort_transaction 2016-07-27 09:47:33 -07:00
ctree.h btrfs: store and load values of stripes_min/stripes_max in balance status item 2017-01-06 11:16:06 +01:00
delayed-inode.c btrfs: limit async_work allocation and worker func duration 2017-01-06 11:16:06 +01:00
delayed-inode.h btrfs: properly set the termination value of ctx->pos in readdir 2016-02-25 12:01:15 -08:00
delayed-ref.c btrfs: qgroup: Fix a race in delayed_ref which leads to abort trans 2015-10-26 19:44:39 -07:00
delayed-ref.h btrfs: qgroup: Fix a race in delayed_ref which leads to abort trans 2015-10-26 19:44:39 -07:00
dev-replace.c Merge branch 'fix/waitqueue-barriers' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.4 2015-10-12 16:24:40 -07:00
dev-replace.h
dir-item.c
disk-io.c btrfs: properly track when rescan worker is running 2016-09-07 08:32:43 +02:00
disk-io.h Btrfs: add btrfs_read_dev_one_super() to read one specific SB 2015-10-01 17:29:38 +02:00
export.c BTRFS: support NFSv2 export 2015-10-06 06:55:23 -07:00
export.h
extent-tree.c btrfs: fix memory leak in update_space_info failure path 2017-06-14 13:16:24 +02:00
extent-tree.h
extent_io.c Btrfs: fix memory leak in reading btree blocks 2017-01-06 11:16:10 +01:00
extent_io.h btrfs: qgroup: Introduce btrfs_qgroup_reserve_data function 2015-10-21 18:37:45 -07:00
extent_map.c
extent_map.h
file-item.c
file.c fs: add i_blocksize() 2017-06-14 13:16:24 +02:00
free-space-cache.c Merge branch 'for-linus-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2015-12-18 15:35:08 -08:00
free-space-cache.h Btrfs: keep track of largest extent in bitmaps 2015-10-21 18:55:40 -07:00
hash.c
hash.h
inode-item.c Btrfs: consolidate btrfs_error() to btrfs_std_error() 2015-09-29 16:30:00 +02:00
inode-map.c Btrfs: Initialize btrfs_root->highest_objectid when loading tree root and subvolume roots 2016-03-03 15:07:12 -08:00
inode-map.h Btrfs: Initialize btrfs_root->highest_objectid when loading tree root and subvolume roots 2016-03-03 15:07:12 -08:00
inode.c Btrfs: adjust outstanding_extents counter properly when dio write is split 2017-08-06 19:19:46 -07:00
ioctl.c btrfs: prevent to set invalid default subvolid 2017-10-05 09:41:47 +02:00
Kconfig
locking.c btrfs: comment the rest of implicit barriers before waitqueue_active 2015-10-10 18:42:00 +02:00
locking.h
lzo.c
Makefile
math.h
ordered-data.c Btrfs: change how we wait for pending ordered extents 2015-10-21 18:51:40 -07:00
ordered-data.h Btrfs: change how we wait for pending ordered extents 2015-10-21 18:51:40 -07:00
orphan.c
print-tree.c
print-tree.h
props.c btrfs: cleanup iterating over prop_handlers array 2015-10-21 18:28:48 +02:00
props.h
qgroup.c Btrfs: fix qgroup rescan worker initialization 2017-01-06 11:16:06 +01:00
qgroup.h btrfs: waiting on qgroup rescan should not always be interruptible 2016-09-07 08:32:43 +02:00
raid56.c btrfs: comment waitqueue_active implied by locks 2015-10-10 18:35:10 +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: reada: Fix returned errno code 2015-10-21 18:29:50 +02:00
relocation.c btrfs: fix NULL pointer dereference from free_reloc_roots() 2017-10-05 09:41:46 +02:00
root-tree.c Btrfs: fix loading of orphan roots leading to BUG_ON 2016-03-09 15:34:53 -08:00
scrub.c Btrfs: fix scrub preventing unused block groups from being deleted 2015-11-25 05:22:08 -08:00
send.c Btrfs: send, fix failure to rename top level inode due to name collision 2017-10-21 17:09:04 +02:00
send.h
struct-funcs.c
super.c btrfs: resume qgroup rescan on rw remount 2017-09-13 14:09:46 -07:00
sysfs.c Btrfs: rename super_kobj to fsid_kobj 2015-09-29 16:29:59 +02:00
sysfs.h Btrfs: rename btrfs_kobj_rm_device to btrfs_sysfs_rm_device_link 2015-09-29 16:29:59 +02:00
transaction.c Btrfs: fix unprotected list move from unused_bgs to deleted_bgs list 2015-12-10 11:22:38 +00:00
transaction.h btrfs: account for non-CoW'd blocks in btrfs_abort_transaction 2016-07-27 09:47:33 -07:00
tree-defrag.c Btrfs: cleanup: remove unnecessary check before btrfs_free_path is called 2015-08-31 11:46:41 -07:00
tree-log.c Btrfs: fix tree search logic when replaying directory entry deletes 2017-01-06 11:16:06 +01:00
tree-log.h
ulist.c
ulist.h
uuid-tree.c
volumes.c btrfs: remove duplicate const specifier 2017-09-02 07:06:50 +02:00
volumes.h btrfs: fix clashing number of the enhanced balance usage filter 2015-11-25 05:19:50 -08:00
xattr.c Btrfs: fix race when listing an inode's xattrs 2015-11-09 18:34:40 +00:00
xattr.h
zlib.c