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  1. 21 Mar, 2014 9 commits
    • Filipe Manana's avatar
      Btrfs: fix incremental send's decision to delay a dir move/rename · 7b119a8b
      Filipe Manana authored 
      It's possible to change the parent/child relationship between directories
in such a way that if a child directory has a higher inode number than
its parent, it doesn't necessarily means the child rename/move operation
can be performed immediately. The parent migth have its own rename/move
operation delayed, therefore in this case the child needs to have its
rename/move operation delayed too, and be performed after its new parent's
rename/move.

Steps to reproduce the issue:

      $ umount /mnt
      $ mkfs.btrfs -f /dev/sdd
      $ mount /dev/sdd /mnt

      $ mkdir /mnt/A
      $ mkdir /mnt/B
      $ mkdir /mnt/C
      $ mv /mnt/C /mnt/A
      $ mv /mnt/B /mnt/A/C
      $ mkdir /mnt/A/C/D

      $ btrfs subvolume snapshot -r /mnt /mnt/snap1
      $ btrfs send /mnt/snap1 -f /tmp/base.send

      $ mv /mnt/A/C/D /mnt/A/D2
      $ mv /mnt/A/C/B /mnt/A/D2/B2
      $ mv /mnt/A/C /mnt/A/D2/B2/C2

      $ btrfs subvolume snapshot -r /mnt /mnt/snap2
      $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/incremental.send

The incremental send caused the kernel code to enter an infinite loop when
building the path string for directory C after its references are processed.

The necessary conditions here are that C has an inode number higher than both
A and B, and B as an higher inode number higher than A, and D has the highest
inode number, that is:
    inode_number(A) < inode_number(B) < inode_number(C) < inode_number(D)

The same issue could happen if after the first snapshot there's any number
of intermediary parent directories between A2 and B2, and between B2 and C2.

A test case for xfstests follows, covering this simple case and more advanced
ones, with files and hard links created inside the directories.
Signed-off-by: default avatarFilipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      7b119a8b
    • Filipe Manana's avatar
      Btrfs: remove unnecessary inode generation lookup in send · 425b5daf
      Filipe Manana authored 
      No need to search in the send tree for the generation number of the inode,
we already have it in the recorded_ref structure passed to us.
Signed-off-by: default avatarFilipe David Borba Manana <fdmanana@gmail.com>
Reviewed-by: default avatarLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      425b5daf
    • Filipe Manana's avatar
      Btrfs: fix race when updating existing ref head · 21543bad
      Filipe Manana authored 
      While we update an existing ref head's extent_op, we're not holding
its spinlock, so while we're updating its extent_op contents (key,
flags) we can have a task running __btrfs_run_delayed_refs() that
holds the ref head's lock and sets its extent_op to NULL right after
the task updating the ref head just checked its extent_op was not NULL.
Signed-off-by: default avatarFilipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      21543bad
    • Qu Wenruo's avatar
      btrfs: Add trace for btrfs_workqueue alloc/destroy · c3a46891
      Qu Wenruo authored 
      Since most of the btrfs_workqueue is printed as pointer address,
for easier analysis, add trace for btrfs_workqueue alloc/destroy.
So it is possible to determine the workqueue that a given work belongs
to(by comparing the wq pointer address with alloc trace event).
Signed-off-by: default avatarQu Wenruo <quenruo@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      c3a46891
    • Filipe Manana's avatar
      Btrfs: less fs tree lock contention when using autodefrag · f094c9bd
      Filipe Manana authored 
      When finding new extents during an autodefrag, don't do so many fs tree
lookups to find an extent with a size smaller then the target treshold.
Instead, after each fs tree forward search immediately unlock upper
levels and process the entire leaf while holding a read lock on the leaf,
since our leaf processing is very fast.
This reduces lock contention, allowing for higher concurrency when other
tasks want to write/update items related to other inodes in the fs tree,
as we're not holding read locks on upper tree levels while processing the
leaf and we do less tree searches.

Test:

    sysbench --test=fileio --file-num=512 --file-total-size=16G \
       --file-test-mode=rndrw --num-threads=32 --file-block-size=32768 \
       --file-rw-ratio=3 --file-io-mode=sync --max-time=1800 \
       --max-requests=10000000000 [prepare|run]

(fileystem mounted with -o autodefrag, averages of 5 runs)

Before this change: 58.852Mb/sec throughtput, read 77.589Gb, written 25.863Gb
After this change:  63.034Mb/sec throughtput, read 83.102Gb, written 27.701Gb

Test machine: quad core intel i5-3570K, 32Gb of RAM, SSD.
Signed-off-by: default avatarFilipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      f094c9bd
    • Guangyu Sun's avatar
      Btrfs: return EPERM when deleting a default subvolume · 72de6b53
      Guangyu Sun authored 
      The error message is confusing:

 # btrfs sub delete /mnt/mysub/
 Delete subvolume '/mnt/mysub'
 ERROR: cannot delete '/mnt/mysub' - Directory not empty

The error message does not make sense to me: It's not about deleting a
directory but it's a subvolume, and it doesn't matter if the subvolume is
empty or not.

Maybe EPERM or is more appropriate in this case, combined with an explanatory
kernel log message. (e.g. "subvolume with ID 123 cannot be deleted because
it is configured as default subvolume.")
Reported-by: default avatarKoen De Wit <koen.de.wit@oracle.com>
Signed-off-by: default avatarGuangyu Sun <guangyu.sun@oracle.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.cz>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      72de6b53
    • Filipe Manana's avatar
      Btrfs: add missing kfree in btrfs_destroy_workqueue · ef66af10
      Filipe Manana authored 
      Signed-off-by: default avatarFilipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      ef66af10
    • Filipe Manana's avatar
      Btrfs: cache extent states in defrag code path · 308d9800
      Filipe Manana authored 
      When locking file ranges in the inode's io_tree, cache the first
extent state that belongs to the target range, so that when unlocking
the range we don't need to search in the io_tree again, reducing cpu
time and making and therefore holding the io_tree's lock for a shorter
period.
Signed-off-by: default avatarFilipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      308d9800
    • Josef Bacik's avatar
      Btrfs: fix deadlock with nested trans handles · 3bbb24b2
      Josef Bacik authored 
      Zach found this deadlock that would happen like this

btrfs_end_transaction <- reduce trans->use_count to 0
  btrfs_run_delayed_refs
    btrfs_cow_block
      find_free_extent
	btrfs_start_transaction <- increase trans->use_count to 1
          allocate chunk
	btrfs_end_transaction <- decrease trans->use_count to 0
	  btrfs_run_delayed_refs
	    lock tree block we are cowing above ^^

We need to only decrease trans->use_count if it is above 1, otherwise leave it
alone.  This will make nested trans be the only ones who decrease their added
ref, and will let us get rid of the trans->use_count++ hack if we have to commit
the transaction.  Thanks,

cc: stable@vger.kernel.org
Reported-by: default avatarZach Brown <zab@redhat.com>
Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Tested-by: default avatarZach Brown <zab@redhat.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      3bbb24b2
  3. 10 Mar, 2014 31 commits
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