xfs: mark all internal workqueues as freezable

Workqueues must be explicitly set as freezable to ensure they are frozen
in the assocated part of the hibernation/suspend sequence. Freezing of
workqueues and kernel threads is important to ensure that modifications
are not made on-disk after the hibernation image has been created.
Otherwise, the in-memory state can become inconsistent with what is on
disk and eventually lead to filesystem corruption. We have reports of
free space btree corruptions that occur immediately after restore from
hibernate that suggest the xfs-eofblocks workqueue could be causing
such problems if it races with hibernation.

Mark all of the internal XFS workqueues as freezable to ensure nothing
changes on-disk once the freezer infrastructure freezes kernel threads
and creates the hibernation image.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reported-by: Carlos E. R. <carlos.e.r@opensuse.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: add a few more verifier tests

These were exposed by fsfuzzer runs; without them we fail
in various exciting and sometimes convoluted ways when we
encounter disk corruption.

Without the MAXLEVELS tests we tend to walk off the end of
an array in a loop like this:

        for (i = 0; i < cur->bc_nlevels; i++) {
                if (cur->bc_bufs[i])

Without the dirblklog test we try to allocate more memory
than we could possibly hope for and loop forever:

xfs_dabuf_map()
	nfsb = mp->m_dir_geo->fsbcount;
	irecs = kmem_zalloc(sizeof(irec) * nfsb, KM_SLEEP...

As for the logbsize check, that's the convoluted one.

If logbsize is specified at mount time, it's sanitized
in xfs_parseargs; in particular it makes sure that it's
not > XLOG_MAX_RECORD_BSIZE.

If not specified at mount time, it comes from the superblock
via sb_logsunit; this is limited to 256k at mkfs time as well;
it's copied into m_logbsize in xfs_finish_flags().

However, if for some reason the on-disk value is corrupt and
too large, nothing catches it.  It's a circuitous path, but
that size eventually finds its way to places that make the kernel
very unhappy, leading to oopses in xlog_pack_data() because we
use the size as an index into iclog->ic_data, but the array
is not necessarily that big.

Anyway - bounds checking when we read from disk is a good thing!

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: add debug sysfs attribute set

Create a top-level debug directory for global debug sysfs attributes.
This directory is added and removed on XFS module initialization and
removal respectively for DEBUG mode kernels only. It typically resides
at /sys/fs/xfs/debug. It is located at the top level of the xfs sysfs
hierarchy as attributes might define global behavior or behavior that
must be configured before an xfs mount is available (e.g., log recovery
behavior).

Define the global debug kobject that represents the debug sysfs
directory and add generic attribute show/store helpers to support future
attributes. No debug attributes are exported as of yet.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: export log_recovery_delay to delay mount time log recovery

XFS log recovery has been discovered to have race conditions with
buffers when I/O errors occur. External tools are available to simulate
I/O errors to XFS, but this alone is not sufficient for testing log
recovery. XFS unconditionally resets the inactive region of the log
prior to log recovery to avoid confusion over processing any partially
written log records that might have been written before an unclean
shutdown. Therefore, unconditional write I/O failures at mount time are
caught by the reset sequence rather than log recovery and hinder the
ability to test the latter.

The device-mapper dm-flakey module uses an up/down timer to define a
cycle for when to fail I/Os. Create a pre log recovery delay tunable
that can be used to coordinate XFS log recovery with I/O errors
simulated by dm-flakey. This facilitates coordination in userspace that
allows the reset of stale log blocks to succeed and writes due to log
recovery to fail. For example, define a dm-flakey instance with an
uptime long enough to allow log reset to succeed and a log recovery
delay long enough to allow the dm-flakey uptime to expire.

The 'log_recovery_delay' sysfs tunable is exported under
/sys/fs/xfs/debug and is only enabled for kernels compiled in XFS debug
mode. The value is exported in units of seconds and allows for a delay
of up to 60 seconds. Note that this is for XFS debug and test
instrumentation purposes only and should not be used by applications. No
delay is enabled by default.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: combine xfs_seek_hole & xfs_seek_data

xfs_seek_hole & xfs_seek_data are remarkably similar;
so much so that they can be combined, saving a fair
bit of semi-complex code duplication.

The following patch passes generic/285 and generic/286,
which specifically test seek behavior.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: lseek: the "whence" argument is called "whence"

For some reason, the older commit:

    965c8e5 lseek: the "whence" argument is called "whence"

    lseek: the "whence" argument is called "whence"

    But the kernel decided to call it "origin" instead.
    Fix most of the sites.

left out xfs.  So fix xfs.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: deduplicate xlog_do_recovery_pass()

In xlog_do_recovery_pass(), there are 2 distinct cases:
non-wrapped and wrapped log recovery.

If we find a wrapped log, we recover around the end
of the log, and then handle the rest of recovery
exactly as in the non-wrapped case - using exactly the same
(duplicated) code.

Rather than having the same code in both cases, we can
get the wrapped portion out of the way first if needed,
and then recover the non-wrapped portion of the log.

There should be no functional change here, just code
reorganization & deduplication.

The patch looks a bit bigger than it really is; the last
hunk is whitespace changes (un-indenting).

Tested with xfstests "check -g log" on a stock configuration.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: check resblks before calling xfs_dir_canenter

Move the resblks test out of the xfs_dir_canenter,
and into the caller.

This makes a little more sense on the face of it;
xfs_dir_canenter immediately returns if resblks !=0;
and given some of the comments preceding the calls:

 * Check for ability to enter directory entry, if no space reserved.

even more so.

It also facilitates the next patch.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: combine xfs_dir_canenter into xfs_dir_createname

xfs_dir_canenter and xfs_dir_createname are
almost identical.

Fold the former into the latter, with a helpful
wrapper for the former.  If createname is called without
an inode number, it now only checks for space, and does
not actually add the entry.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: combine xfs_rtmodify_summary and xfs_rtget_summary

xfs_rtmodify_summary and xfs_rtget_summary are almost identical;
fold them into xfs_rtmodify_summary_int(), with wrappers for each of
the original calls.

The _int function modifies if a delta is passed, and returns a
summary pointer if *sum is passed.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: remove rbpp check from xfs_rtmodify_summary_int

rbpp is always passed into xfs_rtmodify_summary
and xfs_rtget_summary, so there is no need to
test for it in xfs_rtmodify_summary_int.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Merge branch 'xfs-misc-fixes-for-3.18-1' into for-next
xfs: ensure WB_SYNC_ALL writeback handles partial pages correctly

XFS has been having trouble with stray delayed allocation extents
beyond EOF for a long time. Recent changes to the collapse range
code has triggered erroneous EBUSY errors on page invalidtion for
block size smaller than page size filesystems. These
have been caused by dirty buffers beyond EOF on a partial page which
do not get written to disk during a sync.

The issue is that write-ahead in xfs_cluster_write() finds such a
partial page and handles it by leaving the page dirty but pushing it
into a writeback state. This used to work just fine, as the
write_cache_pages() code would then find the dirty partial page in
the next mapping tree lookup as the dirty tag is still set.

Unfortunately, when we moved to a mark and sweep approach to
writeback to fix other writeback sync issues, we broken this. THe
act of marking the page as under writeback now clears the TOWRITE
tag in the radix tree, even though the page is still dirty. This
causes the TOWRITE tag to be cleared, and hence the next lookup on
the mapping tree does not find the dirty partial page and so doesn't
try to write it again.

This same writeback bug was found recently in ext4 and fixed in
commit 1c8349a ("ext4: fix data integrity sync in ordered mode")
without communication to the wider filesystem community. We can use
exactly the same fix here so the TOWRITE flag is not cleared on
partial page writes.

cc: stable@vger.kernel.org # dependent on 1c8349a17137b93f0a83f276c764a6df1b9a116e
Root-cause-found-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: track collapse via file offset rather than extent index

The collapse range implementation uses a transaction per extent shift.
The progress of the overall operation is tracked via the current extent
index of the in-core extent list. This is racy because the ilock must be
dropped and reacquired for each transaction according to locking and log
reservation rules. Therefore, writeback to prior regions of the file is
possible and can change the extent count. This changes the extent to
which the current index refers and causes the collapse to fail mid
operation. To avoid this problem, the entire file is currently written
back before the collapse operation starts.

To eliminate the need to flush the entire file, use the file offset
(fsb) to track the progress of the overall extent shift operation rather
than the extent index. Modify xfs_bmap_shift_extents() to
unconditionally convert the start_fsb parameter to an extent index and
return the file offset of the extent where the shift left off, if
further extents exist. The bulk of ths function can remain based on
extent index as ilock is held by the caller. xfs_collapse_file_space()
now uses the fsb output as the starting point for the subsequent shift.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: refactor shift-by-merge into xfs_bmse_merge() helper

The extent shift mechanism in xfs_bmap_shift_extents() is complicated
and handles several different, non-deterministic scenarios. These
include extent shifts, extent merges and potential btree updates in
either of the former scenarios.

Refactor the code to be more linear and readable. The loop logic in
xfs_bmap_shift_extents() and some initial error checking is adjusted
slightly. The associated btree lookup and update/delete operations are
condensed into single blocks of code. This reduces the number of
btree-specific blocks and facilitates the separation of the merge
operation into a new xfs_bmse_merge() and xfs_bmse_can_merge() helpers.

This is a code refactor only. The behavior of extent shift and collapse
range is not modified.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: refactor single extent shift into xfs_bmse_shift_one() helper

xfs_bmap_shift_extents() has a variety of conditions and error checks
that make the logic difficult to follow and indent heavy. Refactor the
loop body of this function into a new xfs_bmse_shift_one() helper. This
simplifies the error checks, eliminates index decrement on merge hack by
pushing the index increment down into the helper, and makes the code
more readable by reducing multiple levels of indentation.

This is a code refactor only. The behavior of extent shift and collapse
range is not modified.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: writeback and inval. file range to be shifted by collapse

The collapse range operation currently writes the entire file before
starting the collapse to avoid changes in the in-core extent list due to
writeback causing the extent count to change. Now that collapse range is
fsb based rather than extent index based it can sustain changes in the
extent list during the shift sequence without disruption.

Modify xfs_collapse_file_space() to writeback and invalidate pages
associated with the range of the file to be shifted.
xfs_free_file_space() currently has similar behavior, but the space free
need only affect the region of the file that is freed and this could
change in the future.

Also update the comments to reflect the current implementation. We
retain the eofblocks trim permanently as a best option for dealing with
delalloc extents. We don't shift delalloc extents because this scenario
only occurs with post-eof preallocation (since data must be flushed such
that the cache can be invalidated and data can be shifted). That means
said space must also be initialized before being shifted into the
accessible region of the file only to be immediately truncated off as
the last part of the collapse. In other words, the eofblocks trim will
happen anyways, we just run it first to ensure the file remains in a
consistent state throughout the collapse.

Finally, detect and fail explicitly in the event of a delalloc extent
during the extent shift. The implementation does not support delalloc
extents and the caller is expected to prevent this scenario in advance
as is done by collapse.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs: only writeback and truncate pages for the freed range

xfs_free_file_space() only affects the range of the file for which space
is being freed. It currently writes and truncates the page cache from
the start offset of the free to EOF.

Modify xfs_free_file_space() to write back and truncate page cache of
just the range being freed.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Merge branch 'xfs-shift-extents-rework' into for-next
xfs: xlog_cil_force_lsn doesn't always wait correctly

When running a tight mount/unmount loop on an older kernel, RedHat
QE found that unmount would occasionally hang in
xfs_buf_unpin_wait() on the superblock buffer. Tracing and other
debug work by Eric Sandeen indicated that it was hanging on the
writing of the superblock during unmount immediately after logging
the superblock counters in a synchronous transaction. Further debug
indicated that the synchronous transaction was not waiting for
completion correctly, and we narrowed it down to
xlog_cil_force_lsn() returning NULLCOMMITLSN and hence not pushing
the transaction in the iclog buffer to disk correctly.

While this unmount superblock write code is now very different in
mainline kernels, the xlog_cil_force_lsn() code is identical, and it
was bisected to the backport of commit f876e44 ("xfs: always do log
forces via the workqueue"). This commit made the CIL push
asynchronous for log forces and hence exposed a race condition that
couldn't occur on a synchronous push.

Essentially, the xlog_cil_force_lsn() relied implicitly on the fact
that the sequence push would be complete by the time
xlog_cil_push_now() returned, resulting in the context being pushed
being in the committing list. When it was made asynchronous, it was
recognised that there was a race condition in detecting whether an
asynchronous push has started or not and code was added to handle
it.

Unfortunately, the fix was not quite right and left a race condition
where it it would detect an empty CIL while a push was in progress
before the context had been added to the committing list. This was
incorrectly seen as a "nothing to do" condition and so would tell
xfs_log_force_lsn() that there is nothing to wait for, and hence it
would push the iclogbufs in memory.

The fix is simple, but explaining the logic and the race condition
is a lot more complex. The fix is to add the context to the
committing list before we start emptying the CIL. This allows us to
detect the difference between an empty "do nothing" push and a push
that has not started by adding a discrete "emptying the CIL" state
to avoid the transient, incorrect "empty" condition that the
(unchanged) waiting code was seeing.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>