Removes unneeded semicolon, introduced by commit a70a4fa5 ("xfs: fix
a couple error sequence jumps in xfs_mountfs"):

fs/xfs/xfs_mount.c:858:24-25: Unneeded semicolon

Generated by: scripts/coccinelle/misc/semicolon.cocci
Signed-off-by: NFengguang Wu <fengguang.wu@intel.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

We need to treat both inodes identically from a page cache point of
view when prepareing them for extent swapping. We don't do this
right now - we assume that one of the inodes empty, because that's
what xfs_fsr currently does. Remove this assumption from the code.

While factoring out the flushing and related checks, move the
transactions reservation to immeidately after the flushes so that we
don't need to pick up and then drop the ilock to do the transaction
reservation. There are no issues with aborting the transaction it if
the checks fail before we join the inodes to the transaction and
dirty them, so this is a safe change to make.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

xfs_swap_extents() holds the ilock over a call to
filemap_write_and_wait(), which can then try to write data and take
the ilock. That causes a self-deadlock.

Fix the deadlock and clean up the code by separating the locking
appropriately. Add a lockflags variable to track what locks we are
holding as we gain and drop them and cleanup the error handling to
always use "out_unlock" with the lockflags variable.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

Move the IO flag definitions to xfs_inode.h and kill the header file
as it is now empty.

Removing the xfs_vnode.h file showed up an implicit header include
path:
	xfs_linux.h -> xfs_vnode.h -> xfs_fs.h

And so every xfs header file has been inplicitly been including
xfs_fs.h where it is needed or not. Hence the removal of xfs_vnode.h
causes all sorts of build issues because BBTOB() and friends are no
longer automatically included in the build. This also gets fixed.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

Only one user, no longer needed.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

Only has 2 users, has outlived it's usefulness.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

Only one user of the macro and the dirty mapping check is redundant
so just get rid of it.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

dquot recovery should add verifiers to the dquot buffers that it
recovers changes into. Unfortunately, it doesn't attached the
verifiers to the buffers in a consistent manner. For example,
xlog_recover_dquot_pass2() reads dquot buffers without a verifier
and then writes it without ever having attached a verifier to the
buffer.

Further, dquot buffer recovery may write a dquot buffer that has not
been modified, or indeed, shoul dbe written because quotas are not
enabled and hence changes to the buffer were not replayed. In this
case, we again write buffers without verifiers attached because that
doesn't happen until after the buffer changes have been replayed.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

When running xfs/305, I noticed that quotacheck was flushing dquot
buffers that did not have the xfs_dquot_buf_ops verifiers attached:

XFS (vdb): _xfs_buf_ioapply: no ops on block 0x1dc8/0x1dc8
ffff880052489000: 44 51 01 04 00 00 65 b8 00 00 00 00 00 00 00 00  DQ....e.........
ffff880052489010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
ffff880052489020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
ffff880052489030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
CPU: 1 PID: 2376 Comm: mount Not tainted 3.16.0-rc2-dgc+ #306
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
 ffff88006fe38000 ffff88004a0ffae8 ffffffff81cf1cca 0000000000000001
 ffff88004a0ffb88 ffffffff814d50ca 000010004a0ffc70 0000000000000000
 ffff88006be56dc4 0000000000000021 0000000000001dc8 ffff88007c773d80
Call Trace:
 [<ffffffff81cf1cca>] dump_stack+0x45/0x56
 [<ffffffff814d50ca>] _xfs_buf_ioapply+0x3ca/0x3d0
 [<ffffffff810db520>] ? wake_up_state+0x20/0x20
 [<ffffffff814d51f5>] ? xfs_bdstrat_cb+0x55/0xb0
 [<ffffffff814d513b>] xfs_buf_iorequest+0x6b/0xd0
 [<ffffffff814d51f5>] xfs_bdstrat_cb+0x55/0xb0
 [<ffffffff814d53ab>] __xfs_buf_delwri_submit+0x15b/0x220
 [<ffffffff814d6040>] ? xfs_buf_delwri_submit+0x30/0x90
 [<ffffffff814d6040>] xfs_buf_delwri_submit+0x30/0x90
 [<ffffffff8150f89d>] xfs_qm_quotacheck+0x17d/0x3c0
 [<ffffffff81510591>] xfs_qm_mount_quotas+0x151/0x1e0
 [<ffffffff814ed01c>] xfs_mountfs+0x56c/0x7d0
 [<ffffffff814f0f12>] xfs_fs_fill_super+0x2c2/0x340
 [<ffffffff811c9fe4>] mount_bdev+0x194/0x1d0
 [<ffffffff814f0c50>] ? xfs_finish_flags+0x170/0x170
 [<ffffffff814ef0f5>] xfs_fs_mount+0x15/0x20
 [<ffffffff811ca8c9>] mount_fs+0x39/0x1b0
 [<ffffffff811e4d67>] vfs_kern_mount+0x67/0x120
 [<ffffffff811e757e>] do_mount+0x23e/0xad0
 [<ffffffff8117abde>] ? __get_free_pages+0xe/0x50
 [<ffffffff811e71e6>] ? copy_mount_options+0x36/0x150
 [<ffffffff811e8103>] SyS_mount+0x83/0xc0
 [<ffffffff81cfd40b>] tracesys+0xdd/0xe2

This was caused by dquot buffer readahead not attaching a verifier
structure to the buffer when readahead was issued, resulting in the
followup read of the buffer finding a valid buffer and so not
attaching new verifiers to the buffer as part of the read.

Also, when a verifier failure occurs, we then read the buffer
without verifiers. Attach the verifiers manually after this read so
that if the buffer is then written it will be verified that the
corruption has been repaired.

Further, when flushing a dquot we don't ask for a verifier when
reading in the dquot buffer the dquot belongs to. Most of the time
this isn't an issue because the buffer is still cached, but when it
is not cached it will result in writing the dquot buffer without
having the verfier attached.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

Crash testing of CRC enabled filesystems has resulted in a number of
reports of bad CRCs being detected after the filesystem was mounted.
Errors such as the following were being seen:

XFS (sdb3): Mounting V5 Filesystem
XFS (sdb3): Starting recovery (logdev: internal)
XFS (sdb3): Metadata CRC error detected at xfs_agf_read_verify+0x5a/0x100 [xfs], block 0x1
XFS (sdb3): Unmount and run xfs_repair
XFS (sdb3): First 64 bytes of corrupted metadata buffer:
ffff880136ffd600: 58 41 47 46 00 00 00 01 00 00 00 00 00 0f aa 40  XAGF...........@
ffff880136ffd610: 00 02 6d 53 00 02 77 f8 00 00 00 00 00 00 00 01  ..mS..w.........
ffff880136ffd620: 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 03  ................
ffff880136ffd630: 00 00 00 04 00 08 81 d0 00 08 81 a7 00 00 00 00  ................
XFS (sdb3): metadata I/O error: block 0x1 ("xfs_trans_read_buf_map") error 74 numblks 1

The errors were typically being seen in AGF, AGI and their related
btree block buffers some time after log recovery had run. Often it
wasn't until later subsequent mounts that the problem was
discovered. The common symptom was a buffer with the correct
contents, but a CRC and an LSN that matched an older version of the
contents.

Some debug added to _xfs_buf_ioapply() indicated that buffers were
being written without verifiers attached to them from log recovery,
and Jan Kara isolated the cause to log recovery readahead an dit's
interactions with buffers that had a more recent LSN on disk than
the transaction being recovered. In this case, the buffer did not
get a verifier attached, and os when the second phase of log
recovery ran and recovered EFIs and unlinked inodes, the buffers
were modified and written without the verifier running. Hence they
had up to date contents, but stale LSNs and CRCs.

Fix it by attaching verifiers to buffers we skip due to future LSN
values so they don't escape into the buffer cache without the
correct verifier attached.

This patch is based on analysis and a patch from Jan Kara.

cc: <stable@vger.kernel.org>
Reported-by: NJan Kara <jack@suse.cz>
Reported-by: NFanael Linithien <fanael4@gmail.com>
Reported-by: NGrozdan <neutrino8@gmail.com>
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

We recently had a bug where buffers were slipping through log
recovery without any verifier attached to them. This was resulting
in on-disk CRC mismatches for valid data. Add some warning code to
catch this occurrence so that we catch such bugs during development
rather than not being aware they exist.

Note that we cannot do this verification unconditionally as non-CRC
filesystems don't always attach verifiers to the buffers being
written. e.g. during log recovery we cannot identify all the
different types of buffers correctly on non-CRC filesystems, so we
can't attach the correct verifiers in all cases and so we don't
attach any. Hence we don't want on non-CRC filesystems to avoid
spamming the logs with false indications.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

The commit

83e782e1 xfs: Remove incore use of XFS_OQUOTA_ENFD and XFS_OQUOTA_CHKD

added a new function xfs_sb_quota_from_disk() which swaps
on-disk XFS_OQUOTA_* flags for in-core XFS_GQUOTA_* and XFS_PQUOTA_*
flags after the superblock is read.

However, if log recovery is required, the superblock is read again,
and the modified in-core flags are re-read from disk, so we have
XFS_OQUOTA_* flags in memory again.  This causes the
XFS_QM_NEED_QUOTACHECK() test to be true, because the XFS_OQUOTA_CHKD
is still set, and not XFS_GQUOTA_CHKD or XFS_PQUOTA_CHKD.

Change xfs_sb_from_disk to call xfs_sb_quota_from disk and always
convert the disk flags to in-memory flags.

Add a lower-level function which can be called with "false" to
not convert the flags, so that the sb verifier can verify
exactly what was on disk, per Brian Foster's suggestion.
Reported-by: NCyril B. <cbay@excellency.fr>
Signed-off-by: NEric Sandeen <sandeen@redhat.com>

The offset and length parameters are converted from bytes to basic
blocks by xfs_vn_fiemap(). The BTOBB() converter rounds the value up to
the nearest basic block. This leads to unexpected behavior when
unaligned offsets are provided to FIEMAP.

Fix the conversions of byte values to block values to cover the provided
offsets. Round down the start offset to the nearest basic block.
Calculate the end offset based on the provided values, round up and
calculate length based on the start block offset.
Reported-by: NChandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

Introduce xfs_bulkstat_ag_ichunk() to process inodes in chunk with a
pointer to a formatter function that will iget the inode and fill in
the appropriate structure.

Refactor xfs_bulkstat() with it.
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

Trying to support tiny disks only and saving a bit memory might have
made sense on an SGI O2 15 years ago, but is pretty pointless today.

Remove the rarely tested codepath that uses various smaller in-memory
types to reduce our test matrix and make the codebase a little bit
smaller and less complicated.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NBen Myers <bpm@sgi.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

We are intended to check up uflags against FS_PROJ_QUOTA rather than
FS_USER_UQUOTA once more, it looks to me like a typo, but might cause
the project quota metadata space can not be removed.
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

Remove the XFS_IS_OQUOTA_ON macros as it is obsoleted.
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

xfs_set_inode32() caught my eye because it had weird spacing around
the "-1's".  In cleaning that up, I realized that the assignment in
the declaration of "ino" is never used; it's rewritten before it
gets read.

Drop the ino initializer from its declaration since it's not used,
and move the agino initialization into the body of the function,
mostly so that we can have pretty whitespace and not exceed 80
columns.  :)
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

Today, if we perform an xfs_growfs which adds allocation groups,
mp->m_maxagi is not properly updated when the growfs is complete.

Therefore inodes will continue to be allocated only in the
AGs which existed prior to the growfs, and the new space
won't be utilized.

This is because of this path in xfs_growfs_data_private():

xfs_growfs_data_private
	xfs_initialize_perag(mp, nagcount, &nagimax);
		if (mp->m_flags & XFS_MOUNT_32BITINODES)
			index = xfs_set_inode32(mp);
		else
			index = xfs_set_inode64(mp);

		if (maxagi)
			*maxagi = index;

where xfs_set_inode* iterates over the (old) agcount in
mp->m_sb.sb_agblocks, which has not yet been updated
in the growfs path.  So "index" will be returned based on
the old agcount, not the new one, and new AGs are not available
for inode allocation.

Fix this by explicitly passing the proper AG count (which
xfs_initialize_perag() already has) down another level,
so that xfs_set_inode* can make the proper decision about
acceptable AGs for inode allocation in the potentially
newly-added AGs.

This has been broken since 3.7, when these two
xfs_set_inode* functions were added in commit 2d2194f6.
Prior to that, we looped over "agcount" not sb_agblocks
in these calculations.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

xfs_qm_quotacheck() is not used outside of xfs_qm.c.  Mark it static
and move it around in the file to avoid a forward declaration.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

When the CIL checkpoint is fully written to the log, the LSN of the checkpoint
commit record is written into the CIL context structure. This allows log force
waiters to correctly detect when the checkpoint they are waiting on have been
fully written into the log buffers.

However, the initial context after mount is initialised with a non-zero commit
LSN, so appears to waiters as though it is complete even though it may not have
even been pushed, let alone written to the log buffers. Hence a log force
immediately after a filesystem is mounted may not behave correctly, nor does
commit record ordering if multiple CIL pushes interleave immediately after
mount.

To fix this, make sure the initial context commit LSN is not touched until the
first checkpointis actually pushed.

[dchinner: rewrite commit message]
Signed-off-by: NMark Tinguely <tinguely@sgi.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

From: Brian Foster <bfoster@redhat.com>

Commit 4d559a3b introduced heavy prealloc. squashing to catch the case
of requesting too large a prealloc on smaller filesystems, leading to
repeated flush and retry cycles that occur on ENOSPC. Now that we issue
eofblocks scans on EDQUOT/ENOSPC, squash the prealloc against the
minimum available free space across all applicable quotas as well to
avoid a similar problem of repeated eofblocks scans.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

From: Brian Foster <bfoster@redhat.com>

Speculative preallocation and and the associated throttling metrics
assume we're working with large files on large filesystems. Users have
reported inefficiencies in these mechanisms when we happen to be dealing
with large files on smaller filesystems. This can occur because while
prealloc throttling is aggressive under low free space conditions, it is
not active until we reach 5% free space or less.

For example, a 40GB filesystem has enough space for several files large
enough to have multi-GB preallocations at any given time. If those files
are slow growing, they might reserve preallocation for long periods of
time as well as avoid the background scanner due to frequent
modification. If a new file is written under these conditions, said file
has no access to this already reserved space and premature ENOSPC is
imminent.

To handle this scenario, modify the buffered write ENOSPC handling and
retry sequence to invoke an eofblocks scan. In the smaller filesystem
scenario, the eofblocks scan resets the usage of preallocation such that
when the 5% free space threshold is met, throttling effectively takes
over to provide fair and efficient preallocation until legitimate
ENOSPC.

The eofblocks scan is selective based on the nature of the failure. For
example, an EDQUOT failure in a particular quota will use a filtered
scan for that quota. Because we don't know which quota might have caused
an allocation failure at any given time, we include each applicable
quota determined to be under low free space conditions in the scan.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

From: Brian Foster <bfoster@redhat.com>

The eofblocks scan inode filter uses intersection logic by default.
E.g., specifying both user and group quota ids filters out inodes that
are not covered by both the specified user and group quotas. This is
suitable for behavior exposed to userspace.

Scans that are initiated from within the kernel might require more broad
semantics, such as scanning all inodes under each quota associated with
an inode to alleviate low free space conditions in each.

Create the XFS_EOF_FLAGS_UNION flag to support a conditional union-based
filtering algorithm for eofblocks scans. This flag is intentionally left
out of the valid mask as it is not supported for scans initiated from
userspace.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

From: Brian Foster <bfoster@redhat.com>

The scan owner field represents an optional inode number that is
responsible for the current scan. The purpose is to identify that an
inode is under iolock and as such, the iolock shouldn't be attempted
when trimming eofblocks. This is an internal only field.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

From: Jie Liu <jeff.liu@oracle.com>

Introduce xfs_bulkstat_grab_ichunk() to look up an inode chunk in where
the given inode resides, then grab the record.  Update the data for the
pointed-to record if the inode was not the last in the chunk and there
are some left allocated, return the grabbed inode count on success.

Refactor xfs_bulkstat() with it.
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

From: Jie Liu <jeff.liu@oracle.com>

Introduce xfs_bulkstat_ichunk_ra() to loop over all clusters in the
next inode chunk, then performs readahead if there are any allocated
inodes in that cluster.

Refactor xfs_bulkstat() with it.
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

From: Jie Liu <jeff.liu@oracle.com>

We should not ignore the btree operation errors at xfs_bulkstat() but
to propagate them if any. This patch fix two places in this function
and the remaining things will be fixed with code refactoring thereafter.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

From: Jie Liu <jeff.liu@oracle.com>

Remove the redundant user buffer and count checks as it has already
been validated at xfs_ioc_bulkstat().
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

From: Jie Liu <jeff.liu@oracle.com>

To fetch the file system number tables, we currently just ignore the
errors and proceed to loop over the next AG or bump agino to the next
chunk in case of btree operations failed, that is not properly because
those errors might hint us potential file system problems.

This patch rework xfs_inumbers() to handle the btree operation errors
as well as the loop conditions.
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

From: Jie Liu <jeff.liu@oracle.com>

Consolidate xfs_inumbers() to make the formatter function return correct
error and make the source code looks a bit neat.
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

From: Christoph Hellwig <hch@lst.de>

xfs_bukstat_one doesn't have any failure case that would go away when
called through xfs_bulkstat, so remove the fallback and the now unessecary
xfs_bulkstat_single function.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJie Liu <jeff.liu@oracle.com>
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

From: Jie Liu <jeff.liu@oracle.com>

Remove the redundant BULKSTAT_RV_NOTHING assignment in case of call
xfs_iget() failed at xfs_bulkstat_one_int().
Signed-off-by: NJie Liu <jeff.liu@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <david@fromorbit.com>

Create a sysfs-fs-xfs ABI documentation file for newly added sysfs
attributes. This is created under the testing section.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

Create log attributes to export the current runtime state of the log to
sysfs. Note that the filesystem should be frozen for consistency across
attributes.

The following per-mount attributes are created: log_head_lsn,
log_tail_lsn, reserve_grant_head and write_grant_head. These represent
the physical log head, tail and reserve and write grant heads
respectively. Attribute values are exported in the following format:

	"cycle:[block,byte]"

... where cycle represents the log cycle and [block,bytes] represents
either the basic block or byte offset of the log, depending on the
attribute.  Log sequence number (LSN) values are encoded in basic blocks
and grant heads are encoded in bytes. All values are in decimal format.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

Embed a kobject into the xfs log data structure (xlog). This creates a
'log' subdirectory for every XFS mount instance in sysfs. The lifecycle
of the log kobject is tied to the lifecycle of the log.

Also define a set of generic attribute handlers associated with the log
kobject in preparation for the addition of attributes.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>