linux.git/fs/xfs, branch v3.10

xfs: don't shutdown log recovery on validation errors

2013-06-14T20:59:45+00:00

Unfortunately, we cannot guarantee that items logged multiple times
and replayed by log recovery do not take objects back in time. When
they are taken back in time, the go into an intermediate state which
is corrupt, and hence verification that occurs on this intermediate
state causes log recovery to abort with a corruption shutdown.

Instead of causing a shutdown and unmountable filesystem, don't
verify post-recovery items before they are written to disk. This is
less than optimal, but there is no way to detect this issue for
non-CRC filesystems If log recovery successfully completes, this
will be undone and the object will be consistent by subsequent
transactions that are replayed, so in most cases we don't need to
take drastic action.

For CRC enabled filesystems, leave the verifiers in place - we need
to call them to recalculate the CRCs on the objects anyway. This
recovery problem can be solved for such filesystems - we have a LSN
stamped in all metadata at writeback time that we can to determine
whether the item should be replayed or not. This is a separate piece
of work, so is not addressed by this patch.

Signed-off-by: Dave Chinner 
Reviewed-by: Ben Myers 
Signed-off-by: Ben Myers 

(cherry picked from commit 9222a9cf86c0d64ffbedf567412b55da18763aa3)

xfs: ensure btree root split sets blkno correctly

2013-06-14T20:59:31+00:00

For CRC enabled filesystems, the BMBT is rooted in an inode, so it
passes through a different code path on root splits than the
freespace and inode btrees. This is much less traversed by xfstests
than the other trees. When testing on a 1k block size filesystem,
I've been seeing ASSERT failures in generic/234 like:

XFS: Assertion failed: cur->bc_btnum != XFS_BTNUM_BMAP || cur->bc_private.b.allocated == 0, file: fs/xfs/xfs_btree.c, line: 317

which are generally preceded by a lblock check failure. I noticed
this in the bmbt stats:

$ pminfo -f xfs.btree.block_map

xfs.btree.block_map.lookup
value 39135

xfs.btree.block_map.compare
value 268432

xfs.btree.block_map.insrec
value 15786

xfs.btree.block_map.delrec
value 13884

xfs.btree.block_map.newroot
value 2

xfs.btree.block_map.killroot
value 0
.....

Very little coverage of root splits and merges. Indeed, on a 4k
filesystem, block_map.newroot and block_map.killroot are both zero.
i.e. the code is not exercised at all, and it's the only generic
btree infrastructure operation that is not exercised by a default run
of xfstests.

Turns out that on a 1k filesystem, generic/234 accounts for one of
those two root splits, and that is somewhat of a smoking gun. In
fact, it's the same problem we saw in the directory/attr code where
headers are memcpy()d from one block to another without updating the
self describing metadata.

Simple fix - when copying the header out of the root block, make
sure the block number is updated correctly.

Signed-off-by: Dave Chinner
Reviewed-by: Ben Myers
Signed-off-by: Ben Myers

(cherry picked from commit ade1335afef556df6538eb02e8c0dc91fbd9cc37)

xfs: fix implicit padding in directory and attr CRC formats

2013-06-14T20:59:16+00:00

Michael L. Semon has been testing CRC patches on a 32 bit system and
been seeing assert failures in the directory code from xfs/080.
Thanks to Michael's heroic efforts with printk debugging, we found
that the problem was that the last free space being left in the
directory structure was too small to fit a unused tag structure and
it was being corrupted and attempting to log a region out of bounds.
Hence the assert failure looked something like:

.....
#5 calling xfs_dir2_data_log_unused() 36 32
#1 4092 4095 4096
#2 8182 8183 4096
XFS: Assertion failed: first <= last && last < BBTOB(bp->b_length), file: fs/xfs/xfs_trans_buf.c, line: 568

Where #1 showed the first region of the dup being logged (i.e. the
last 4 bytes of a directory buffer) and #2 shows the corrupt values
being calculated from the length of the dup entry which overflowed
the size of the buffer.

It turns out that the problem was not in the logging code, nor in
the freespace handling code. It is an initial condition bug that
only shows up on 32 bit systems. When a new buffer is initialised,
where's the freespace that is set up:

[ 172.316249] calling xfs_dir2_leaf_addname() from xfs_dir_createname()
[ 172.316346] #9 calling xfs_dir2_data_log_unused()
[ 172.316351] #1 calling xfs_trans_log_buf() 60 63 4096
[ 172.316353] #2 calling xfs_trans_log_buf() 4094 4095 4096

Note the offset of the first region being logged? It's 60 bytes into
the buffer. Once I saw that, I pretty much knew that the bug was
going to be caused by this.

Essentially, all direct entries are rounded to 8 bytes in length,
and all entries start with an 8 byte alignment. This means that we
can decode inplace as variables are naturally aligned. With the
directory data supposedly starting on a 8 byte boundary, and all
entries padded to 8 bytes, the minimum freespace in a directory
block is supposed to be 8 bytes, which is large enough to fit a
unused data entry structure (6 bytes in size). The fact we only have
4 bytes of free space indicates a directory data block alignment
problem.

And what do you know - there's an implicit hole in the directory
data block header for the CRC format, which means the header is 60
byte on 32 bit intel systems and 64 bytes on 64 bit systems. Needs
padding. And while looking at the structures, I found the same
problem in the attr leaf header. Fix them both.

Note that this only affects 32 bit systems with CRCs enabled.
Everything else is just fine. Note that CRC enabled filesystems created
before this fix on such systems will not be readable with this fix
applied.

Reported-by: Michael L. Semon
Debugged-by: Michael L. Semon
Signed-off-by: Dave Chinner
Reviewed-by: Ben Myers
Signed-off-by: Ben Myers

(cherry picked from commit 8a1fd2950e1fe267e11fc8c85dcaa6b023b51b60)

xfs: don't emit v5 superblock warnings on write

2013-06-14T20:58:47+00:00

We write the superblock every 30s or so which results in the
verifier being called. Right now that results in this output
every 30s:

XFS (vda): Version 5 superblock detected. This kernel has EXPERIMENTAL support enabled!
Use of these features in this kernel is at your own risk!

And spamming the logs.

We don't need to check for whether we support v5 superblocks or
whether there are feature bits we don't support set as these are
only relevant when we first mount the filesytem. i.e. on superblock
read. Hence for the write verification we can just skip all the
checks (and hence verbose output) altogether.

Signed-off-by: Dave Chinner 
Reviewed-by: Brian Foster 
Signed-off-by: Ben Myers 

(cherry picked from commit 34510185abeaa5be9b178a41c0a03d30aec3db7e)

xfs: increase number of ACL entries for V5 superblocks

2013-06-06T15:52:15+00:00

The limit of 25 ACL entries is arbitrary, but baked into the on-disk
format.  For version 5 superblocks, increase it to the maximum nuber
of ACLs that can fit into a single xattr.

Signed-off-by: Dave Chinner 
Reviewed-by: Brian Foster 
Reviewed-by: Mark Tinguely 
Signed-off-by: Ben Myers 

(cherry picked from commit 5c87d4bc1a86bd6e6754ac3d6e111d776ddcfe57)

xfs: disable noattr2/attr2 mount options for CRC enabled filesystems

2013-06-06T15:51:34+00:00

attr2 format is always enabled for v5 superblock filesystems, so the
mount options to enable or disable it need to be cause mount errors.

Signed-off-by: Dave Chinner 
Reviewed-by: Brian Foster 
Signed-off-by: Ben Myers 

(cherry picked from commit d3eaace84e40bf946129e516dcbd617173c1cf14)

xfs: inode unlinked list needs to recalculate the inode CRC

2013-06-06T15:51:19+00:00

The inode unlinked list manipulations operate directly on the inode
buffer, and so bypass the inode CRC calculation mechanisms. Hence an
inode on the unlinked list has an invalid CRC. Fix this by
recalculating the CRC whenever we modify an unlinked list pointer in
an inode, ncluding during log recovery. This is trivial to do and
results in  unlinked list operations always leaving a consistent
inode in the buffer.

Signed-off-by: Dave Chinner 
Reviewed-by: Mark Tinguely 
Signed-off-by: Ben Myers 

(cherry picked from commit 0a32c26e720a8b38971d0685976f4a7d63f9e2ef)

xfs: fix log recovery transaction item reordering

2013-06-06T15:51:07+00:00

There are several constraints that inode allocation and unlink
logging impose on log recovery. These all stem from the fact that
inode alloc/unlink are logged in buffers, but all other inode
changes are logged in inode items. Hence there are ordering
constraints that recovery must follow to ensure the correct result
occurs.

As it turns out, this ordering has been working mostly by chance
than good management. The existing code moves all buffers except
cancelled buffers to the head of the list, and everything else to
the tail of the list. The problem with this is that is interleaves
inode items with the buffer cancellation items, and hence whether
the inode item in an cancelled buffer gets replayed is essentially
left to chance.

Further, this ordering causes problems for log recovery when inode
CRCs are enabled. It typically replays the inode unlink buffer long before
it replays the inode core changes, and so the CRC recorded in an
unlink buffer is going to be invalid and hence any attempt to
validate the inode in the buffer is going to fail. Hence we really
need to enforce the ordering that the inode alloc/unlink code has
expected log recovery to have since inode chunk de-allocation was
introduced back in 2003...

Signed-off-by: Dave Chinner 
Reviewed-by: Mark Tinguely 
Signed-off-by: Ben Myers 

(cherry picked from commit a775ad778073d55744ed6709ccede36310638911)

xfs: fix remote attribute invalidation for a leaf

2013-06-06T15:50:52+00:00

When invalidating an attribute leaf block block, there might be
remote attributes that it points to. With the recent rework of the
remote attribute format, we have to make sure we calculate the
length of the attribute correctly. We aren't doing that in
xfs_attr3_leaf_inactive(), so fix it.

Signed-off-by: Dave Chinner 
Reviewed-by: Brian Foster 
Reviewed-by: Mark Tinguely 
Signed-off-by: Ben Myers 

(cherry picked from commit 59913f14dfe8eb772ff93eb442947451b4416329)

xfs: rework dquot CRCs

2013-06-06T15:50:35+00:00

Calculating dquot CRCs when the backing buffer is written back just
doesn't work reliably. There are several places which manipulate
dquots directly in the buffers, and they don't calculate CRCs
appropriately, nor do they always set the buffer up to calculate
CRCs appropriately.

Firstly, if we log a dquot buffer (e.g. during allocation) it gets
logged without valid CRC, and so on recovery we end up with a dquot
that is not valid.

Secondly, if we recover/repair a dquot, we don't have a verifier
attached to the buffer and hence CRCs are not calculated on the way
down to disk.

Thirdly, calculating the CRC after we've changed the contents means
that if we re-read the dquot from the buffer, we cannot verify the
contents of the dquot are valid, as the CRC is invalid.

So, to avoid all the dquot CRC errors that are being detected by the
read verifier, change to using the same model as for inodes. That
is, dquot CRCs are calculated and written to the backing buffer at
the time the dquot is flushed to the backing buffer. If we modify
the dquot directly in the backing buffer, calculate the CRC
immediately after the modification is complete. Hence the dquot in
the on-disk buffer should always have a valid CRC.

Signed-off-by: Dave Chinner 
Reviewed-by: Brian Foster 
Reviewed-by: Ben Myers 
Signed-off-by: Ben Myers 

(cherry picked from commit 6fcdc59de28817d1fbf1bd58cc01f4f3fac858fb)