When we are checking if we need to delay the rename operation for an
inode we not checking if a parent inode that exists in the send and
parent snapshots is really the same inode or not, that is, we are not
comparing the generation number of the parent inode in the send and
parent snapshots. Not only this results in unnecessarily delaying a
rename operation but also can later on make us generate an incorrect
name for a new inode in the send snapshot that has the same number
as another inode in the parent snapshot but a different generation.
Here follows an example where this happens.
Parent snapshot:
. (ino 256, gen 3)
|--- dir258/ (ino 258, gen 7)
| |--- dir257/ (ino 257, gen 7)
|
|--- dir259/ (ino 259, gen 7)
Send snapshot:
. (ino 256, gen 3)
|--- file258 (ino 258, gen 10)
|
|--- new_dir259/ (ino 259, gen 10)
|--- dir257/ (ino 257, gen 7)
The following steps happen when computing the incremental send stream:
1) When processing inode 257, its new parent is created using its orphan
name (o257-21-0), and the rename operation for inode 257 is delayed
because its new parent (inode 259) was not yet processed - this
decision to delay the rename operation does not make much sense
because the inode 259 in the send snapshot is a new inode, it's not
the same as inode 259 in the parent snapshot.
2) When processing inode 258 we end up delaying its rmdir operation,
because inode 257 was not yet renamed (moved away from the directory
inode 258 represents). We also create the new inode 258 using its
orphan name "o258-10-0", then rename it to its final name of "file258"
and then issue a truncate operation for it. However this truncate
operation contains an incorrect name, which corresponds to the orphan
name and not to the final name, which makes the receiver fail. This
happens because when we attempt to compute the inode's current name
we verify that there's another inode with the same number (258) that
has its rmdir operation pending and because of that we generate an
orphan name for the new inode 258 (we do this in the function
get_cur_path()).
Fix this by not delayed the rename operation of an inode if it has parents
with the same number but different generations in both snapshots.
The following steps reproduce this example scenario.
$ mkfs.btrfs -f /dev/sdb
$ mount /dev/sdb /mnt
$ mkdir /mnt/dir257
$ mkdir /mnt/dir258
$ mkdir /mnt/dir259
$ mv /mnt/dir257 /mnt/dir258/dir257
$ btrfs subvolume snapshot -r /mnt /mnt/snap1
$ mv /mnt/dir258/dir257 /mnt/dir257
$ rmdir /mnt/dir258
$ rmdir /mnt/dir259
# Remount the filesystem so that the next created inodes will have the
# numbers 258 and 259. This is because when a filesystem is mounted,
# btrfs sets the subvolume's inode counter to a value corresponding to
# the highest inode number in the subvolume plus 1. This inode counter
# is used to assign a unique number to each new inode and it's
# incremented by 1 after very inode creation.
# Note: we unmount and then mount instead of doing a mount with
# "-o remount" because otherwise the inode counter remains at value 260.
$ umount /mnt
$ mount /dev/sdb /mnt
$ touch /mnt/file258
$ mkdir /mnt/new_dir259
$ mv /mnt/dir257 /mnt/new_dir259/dir257
$ btrfs subvolume snapshot -r /mnt /mnt/snap2
$ 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/sdc
$ mount /dev/sdc /mnt
$ btrfs receive /mnt -f /tmo/1.snap
$ btrfs receive /mnt -f /tmo/2.snap -vv
receiving snapshot mysnap2 uuid=e059b6d1-7f55-f140-8d7c-9a3039d23c97, ctransid=10 parent_uuid=77e98cb6-8762-814f-9e05-e8ba877fc0b0, parent_ctransid=7
utimes
mkdir o259-10-0
rename dir258 -> o258-7-0
utimes
mkfile o258-10-0
rename o258-10-0 -> file258
utimes
truncate o258-10-0 size=0
ERROR: truncate o258-10-0 failed: No such file or directory
Reported-by: Robbie Ko <robbieko@synology.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
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>
'BTRFS_ORDERED_REGULAR' was introduced for the cow case in patch
'Btrfs: specify a new ordered extent type for create_io_em',
but it missed the directIO cow case.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
Commit e5d6b12fe1 (Btrfs: don't WARN() in btrfs_transaction_abort() for
IO errors) added a pr_debug call to be printed when a transaction is
aborted with -EIO instead of WARN. btrfs_debug prints which file system
the message is associated with so let's use that instead.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_truncate_free_space_cache always allocates a btrfs_path structure
but only uses it when the caller passes a block group. Let's move the
allocation and free into the conditional.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The free space cache APIs accept a root but always use the tree root.
Also, btrfs_truncate_free_space_cache accepts a root AND an inode but
the inode always points to the root anyway, so let's just pass the inode.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_inc_block_group_ro is either passed the extent root or the dev
root, but it doesn't do anything with the dev tree. Let's convert
to passing an fs_info and using the extent root.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We don't need to pass a root to flush_space since it always uses
the fs_root.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Outside of interactions with qgroups, the roots passed in extent-tree.c
are usually passed to ensure that we don't do refcounts on log trees or
to get the allocation profile for an allocation request. Otherwise, it
operates on the extent root. This patch converts some more routines in
extent-tree.c that are always called with the extent root to accept
an fs_info instead.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Just as Filipe pointed out, the most time consuming parts of qgroup are
btrfs_qgroup_account_extents() and
btrfs_qgroup_prepare_account_extents().
Which both call btrfs_find_all_roots() to get old_roots and new_roots
ulist.
What makes things worse is, we're calling that expensive
btrfs_find_all_roots() at transaction committing time with
TRANS_STATE_COMMIT_DOING, which will blocks all incoming transaction.
Such behavior is necessary for @new_roots search as current
btrfs_find_all_roots() can't do it correctly so we do call it just
before switch commit roots.
However for @old_roots search, it's not necessary as such search is
based on commit_root, so it will always be correct and we can move it
out of transaction committing.
This patch moves the @old_roots search part out of
commit_transaction(), so in theory we can half the time qgroup time
consumption at commit_transaction().
But please note that, this won't speedup qgroup overall, the total time
consumption is still the same, just reduce the performance stall.
Cc: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Both unused after the call to update_cache_item has been moved to
__btrfs_wait_cache_io.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Unused since the helper has been split, eb used in the caller.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
After the page locking has been reworked, we get all pages prepared via
cmp_pages.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The name parameters have never been used, as the name is passed via the
dentry.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The 'device' used to be added in that function, but now it's done by the
caller.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Never used for anything meaningful since we have our own superblock
filler.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The 'tree' was used to call locking hook that does not exist anymore.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The logic has been updated in "Btrfs: make mapping->writeback_index
point to the last written page" (a91326679f) and page is not
needed anymore.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This used to hold number of maximum pages to allocate, but this is now
limited by BIO_MAX_PAGES. The local are now unused and removed as well.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
None of the checks need to know the ro/rw status as they're all not
changing the superblock. Moreover, we can access the sb flags directly
if we'd need to decide by the ro/rw status.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Unused since qgroup refactoring that split data and metadata accounting,
the btrfs_qgroup_free helper.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
write_all_supers and write_ctree_super are almost equal, the parameter
'trans' is unused so we can drop it and have just one helper.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Change the name so it matches the naming we already use eg. for
btrfs_path.
Suggested-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There was never need for RCU protection around reading nodesize or other
fairly constant filesystem data.
Signed-off-by: David Sterba <dsterba@suse.com>
The quota status used to be tracked as a variable, so the mutex was
needed (until "Btrfs: add a flags field to btrfs_fs_info" afcdd129e0).
Since the status is a bit modified atomically and we don't hold the
mutex beyond the check, we can drop it.
Signed-off-by: David Sterba <dsterba@suse.com>
Status of quotas should be the first check in
btrfs_qgroup_account_extent and we can return immediatelly, no need to
do no-op ulist frees.
Signed-off-by: David Sterba <dsterba@suse.com>
We can embed range_changed to the extent changeset to address following
problems:
- no need to allocate ulist dynamically, we also get rid of the GFP_NOFS
for free
- fix lack of allocation failure checking in btrfs_qgroup_reserve_data
The stack consuption where extent_changeset is used slightly increases:
before: 16
after: 16 - 8 (for pointer) + 32 (sizeof ulist) = 40
Which is bearable.
Reviewed-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We do a readahead of the free space cache inode to speed things up but
the failure is not fatal, like in other readahead cases. Proper reads
would need to happen anyway and any errors would be caught there.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qgroup relations are added/deleted from ioctl, we hold the high level
qgroup lock, no deadlocks or recursion from the allocation possible
here.
Signed-off-by: David Sterba <dsterba@suse.com>
