linux-toradex.git/fs/btrfs, branch v3.4.93

Btrfs: fix data corruption when reading/updating compressed extents

2014-03-24T04:37:08+00:00

commit a2aa75e18a21b21952dc6daa9bac7c9f4426f81f upstream.

When using a mix of compressed file extents and prealloc extents, it
is possible to fill a page of a file with random, garbage data from
some unrelated previous use of the page, instead of a sequence of zeroes.

A simple sequence of steps to get into such case, taken from the test
case I made for xfstests, is:

   _scratch_mkfs
   _scratch_mount "-o compress-force=lzo"
   $XFS_IO_PROG -f -c "pwrite -S 0x06 -b 18670 266978 18670" $SCRATCH_MNT/foobar
   $XFS_IO_PROG -c "falloc 26450 665194" $SCRATCH_MNT/foobar
   $XFS_IO_PROG -c "truncate 542872" $SCRATCH_MNT/foobar
   $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foobar

This results in the following file items in the fs tree:

   item 4 key (257 INODE_ITEM 0) itemoff 15879 itemsize 160
       inode generation 6 transid 6 size 542872 block group 0 mode 100600
   item 5 key (257 INODE_REF 256) itemoff 15863 itemsize 16
       inode ref index 2 namelen 6 name: foobar
   item 6 key (257 EXTENT_DATA 0) itemoff 15810 itemsize 53
       extent data disk byte 0 nr 0 gen 6
       extent data offset 0 nr 24576 ram 266240
       extent compression 0
   item 7 key (257 EXTENT_DATA 24576) itemoff 15757 itemsize 53
       prealloc data disk byte 12849152 nr 241664 gen 6
       prealloc data offset 0 nr 241664
   item 8 key (257 EXTENT_DATA 266240) itemoff 15704 itemsize 53
       extent data disk byte 12845056 nr 4096 gen 6
       extent data offset 0 nr 20480 ram 20480
       extent compression 2
   item 9 key (257 EXTENT_DATA 286720) itemoff 15651 itemsize 53
       prealloc data disk byte 13090816 nr 405504 gen 6
       prealloc data offset 0 nr 258048

The on disk extent at offset 266240 (which corresponds to 1 single disk block),
contains 5 compressed chunks of file data. Each of the first 4 compress 4096
bytes of file data, while the last one only compresses 3024 bytes of file data.
Therefore a read into the file region [285648 ; 286720[ (length = 4096 - 3024 =
1072 bytes) should always return zeroes (our next extent is a prealloc one).

The solution here is the compression code path to zero the remaining (untouched)
bytes of the last page it uncompressed data into, as the information about how
much space the file data consumes in the last page is not known in the upper layer
fs/btrfs/extent_io.c:__do_readpage(). In __do_readpage we were correctly zeroing
the remainder of the page but only if it corresponds to the last page of the inode
and if the inode's size is not a multiple of the page size.

This would cause not only returning random data on reads, but also permanently
storing random data when updating parts of the region that should be zeroed.
For the example above, it means updating a single byte in the region [285648 ; 286720[
would store that byte correctly but also store random data on disk.

A test case for xfstests follows soon.

Signed-off-by: Filipe David Borba Manana 
Signed-off-by: Chris Mason 
Signed-off-by: Greg Kroah-Hartman

Btrfs: handle EAGAIN case properly in btrfs_drop_snapshot()

2014-02-06T19:05:48+00:00

commit 90515e7f5d7d24cbb2a4038a3f1b5cfa2921aa17 upstream.

We may return early in btrfs_drop_snapshot(), we shouldn't
call btrfs_std_err() for this case, fix it.

Signed-off-by: Wang Shilong 
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason 
Signed-off-by: Greg Kroah-Hartman

Btrfs: change how we queue blocks for backref checking

2013-10-13T22:42:50+00:00

commit b6c60c8018c4e9beb2f83fc82c09f9d033766571 upstream.

Previously we only added blocks to the list to have their backrefs checked if
the level of the block is right above the one we are searching for.  This is
because we want to make sure we don't add the entire path up to the root to the
lists to make sure we process things one at a time.  This assumes that if any
blocks in the path to the root are going to be not checked (shared in other
words) then they will be in the level right above the current block on up.  This
isn't quite right though since we can have blocks higher up the list that are
shared because they are attached to a reloc root.  But we won't add this block
to be checked and then later on we will BUG_ON(!upper->checked).  So instead
keep track of wether or not we've queued a block to be checked in this current
search, and if we haven't go ahead and queue it to be checked.  This patch fixed
the panic I was seeing where we BUG_ON(!upper->checked).  Thanks,

Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason 
Signed-off-by: Greg Kroah-Hartman

Btrfs: re-add root to dead root list if we stop dropping it

2013-08-04T08:25:54+00:00

commit d29a9f629e009c9b90e5859bce581070fd6247fc upstream.

If we stop dropping a root for whatever reason we need to add it back to the
dead root list so that we will re-start the dropping next transaction commit.
The other case this happens is if we recover a drop because we will add a root
without adding it to the fs radix tree, so we can leak it's root and commit root
extent buffer, adding this to the dead root list makes this cleanup happen.
Thanks,

Reported-by: Alex Lyakas 
Signed-off-by: Josef Bacik 
Signed-off-by: Greg Kroah-Hartman

Btrfs: fix lock leak when resuming snapshot deletion

2013-08-04T08:25:54+00:00

commit fec386ac1428f9c0e672df952cbca5cebd4e4e2f upstream.

We aren't setting path->locks[level] when we resume a snapshot deletion which
means we won't unlock the buffer when we free the path.  This causes deadlocks
if we happen to re-allocate the block before we've evicted the extent buffer
from cache.  Thanks,

Reported-by: Alex Lyakas 
Signed-off-by: Josef Bacik 
Signed-off-by: Greg Kroah-Hartman

btrfs: don't stop searching after encountering the wrong item

2013-05-24T18:14:22+00:00

commit 03b71c6ca6286625d8f1ed44aabab9b5bf5dac10 upstream.

The search ioctl skips items that are too large for a result buffer, but
inline items of a certain size occuring before any search result is
found would trigger an overflow and stop the search entirely.

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=57641

Signed-off-by: Gabriel de Perthuis 
Signed-off-by: Josef Bacik 
Signed-off-by: Greg Kroah-Hartman

Btrfs: make sure nbytes are right after log replay

2013-04-26T04:19:56+00:00

commit 4bc4bee4595662d8bff92180d5c32e3313a704b0 upstream.

While trying to track down a tree log replay bug I noticed that fsck was always
complaining about nbytes not being right for our fsynced file.  That is because
the new fsync stuff doesn't wait for ordered extents to complete, so the inodes
nbytes are not necessarily updated properly when we log it.  So to fix this we
need to set nbytes to whatever it is on the inode that is on disk, so when we
replay the extents we can just add the bytes that are being added as we replay
the extent.  This makes it work for the case that we have the wrong nbytes or
the case that we logged everything and nbytes is actually correct.  With this
I'm no longer getting nbytes errors out of btrfsck.

Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason 
Signed-off-by: Lingzhu Xiang 
Reviewed-by: CAI Qian 
Signed-off-by: Greg Kroah-Hartman

Btrfs: fix space leak when we fail to reserve metadata space

2013-04-05T17:04:36+00:00

commit f4881bc7a83eff263789dd524b7c269d138d4af5 upstream.

Dave reported a warning when running xfstest 275.  We have been leaking delalloc
metadata space when our reservations fail.  This is because we were improperly
calculating how much space to free for our checksum reservations.  The problem
is we would sometimes free up space that had already been freed in another
thread and we would end up with negative usage for the delalloc space.  This
patch fixes the problem by calculating how much space the other threads would
have already freed, and then calculate how much space we need to free had we not
done the reservation at all, and then freeing any excess space.  This makes
xfstests 275 no longer have leaked space.  Thanks

Reported-by: David Sterba 
Signed-off-by: Josef Bacik 
Signed-off-by: Lingzhu Xiang 
Reviewed-by: CAI Qian 
Signed-off-by: Greg Kroah-Hartman

Btrfs: don't drop path when printing out tree errors in scrub

2013-04-05T17:04:34+00:00

commit d8fe29e9dea8d7d61fd140d8779326856478fc62 upstream.

A user reported a panic where we were panicing somewhere in
tree_backref_for_extent from scrub_print_warning.  He only captured the trace
but looking at scrub_print_warning we drop the path right before we mess with
the extent buffer to print out a bunch of stuff, which isn't right.  So fix this
by dropping the path after we use the eb if we need to.  Thanks,

Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason 
Signed-off-by: Greg Kroah-Hartman

Btrfs: limit the global reserve to 512mb

2013-04-05T17:04:34+00:00

commit fdf30d1c1b386e1b73116cc7e0fb14e962b763b0 upstream.

A user reported a problem where he was getting early ENOSPC with hundreds of
gigs of free data space and 6 gigs of free metadata space.  This is because the
global block reserve was taking up the entire free metadata space.  This is
ridiculous, we have infrastructure in place to throttle if we start using too
much of the global reserve, so instead of letting it get this huge just limit it
to 512mb so that users can still get work done.  This allowed the user to
complete his rsync without issues.  Thanks

Reported-and-tested-by: Stefan Priebe 
Signed-off-by: Josef Bacik 
Signed-off-by: Greg Kroah-Hartman