linux-toradex.git/fs/xfs/xfs_rtalloc.h, branch v6.2-rc4

xfs: recalculate free rt extents after log recovery

2022-04-11T20:49:42+00:00

I've been observing periodic corruption reports from xfs_scrub involving
the free rt extent counter (frextents) while running xfs/141.  That test
uses an error injection knob to induce a torn write to the log, and an
arbitrary number of recovery mounts, frextents will count fewer free rt
extents than can be found the rtbitmap.

The root cause of the problem is a combination of the misuse of
sb_frextents in the incore mount to reflect both incore reservations
made by running transactions as well as the actual count of free rt
extents on disk.  The following sequence can reproduce the undercount:

Thread 1			Thread 2
xfs_trans_alloc(rtextents=3)
xfs_mod_frextents(-3)

				xfs_attr_set()
				xfs_bmap_attr_addfork()
				xfs_add_attr2()
				xfs_log_sb()
				xfs_sb_to_disk()
				xfs_trans_commit()



Note that thread 1 subtracts 3 from sb_frextents even though it never
commits to using that space.  Thread 2 writes the undercounted value to
the ondisk superblock and logs it to the xattr transaction, which is
then flushed to disk.  At next mount, log recovery will find the logged
superblock and write that back into the filesystem.  At the end of log
recovery, we reread the superblock and install the recovered
undercounted frextents value into the incore superblock.  From that
point on, we've effectively leaked thread 1's transaction reservation.

The correct fix for this is to separate the incore reservation from the
ondisk usage, but that's a matter for the next patch.  Because the
kernel has been logging superblocks with undercounted frextents for a
very long time and we don't demand that sysadmins run xfs_repair after a
crash, fix the undercount by recomputing frextents after log recovery.

Gating this on log recovery is a reasonable balance (I think) between
correcting the problem and slowing down every mount attempt.  Note that
xfs_repair will fix undercounted frextents.

Signed-off-by: Darrick J. Wong 
Reviewed-by: Dave Chinner 
Signed-off-by: Dave Chinner

xfs: pass explicit mount pointer to rtalloc query functions

2022-04-11T20:49:41+00:00

Pass an explicit xfs_mount pointer to the rtalloc query functions so
that they can support transactionless queries.

Signed-off-by: Darrick J. Wong 
Reviewed-by: Dave Chinner 
Signed-off-by: Dave Chinner

xfs: make the record pointer passed to query_range functions const

2021-08-19T01:46:01+00:00

The query_range functions are supposed to call a caller-supplied
function on each record found in the dataset.  These functions don't
own the memory storing the record, so don't let them change the record.

Signed-off-by: Darrick J. Wong 
Reviewed-by: Christoph Hellwig

xfs: make xfs_rtalloc_query_range input parameters const

2021-08-19T01:46:00+00:00

In commit 8ad560d2565e, we changed xfs_rtalloc_query_range to constrain
the range of bits in the realtime bitmap file that would actually be
searched.  In commit a3a374bf1889, we changed the range again
(incorrectly), leading to the fix in commit d88850bd5516, which finally
corrected the range check code.  Unfortunately, the author never noticed
that the function modifies its input parameters, which is a totaly no-no
since none of the other range query functions change their input
parameters.

So, fix this function yet again to stash the upper end of the query
range (i.e. the high key) in a local variable and hope this is the last
time I have to fix my own function.  While we're at it, mark the key
inputs const so nobody makes this mistake again. :(

Fixes: 8ad560d2565e ("xfs: strengthen rtalloc query range checks")
Not-fixed-by: a3a374bf1889 ("xfs: fix off-by-one error in xfs_rtalloc_query_range")
Not-fixed-by: d88850bd5516 ("xfs: fix high key handling in the rt allocator's query_range function")
Signed-off-by: Darrick J. Wong 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Chandan Babu R

xfs: remove xfs_buf_t typedef

2020-12-17T00:07:34+00:00

Prepare for kernel xfs_buf  alignment by getting rid of the
xfs_buf_t typedef from userspace.

[darrick: This patch is a port of a userspace patch removing the
xfs_buf_t typedef in preparation to make the userspace xfs_buf code
behave more like its kernel counterpart.]

Signed-off-by: Dave Chinner 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong 
Reviewed-by: Dave Chinner

xfs: convert to SPDX license tags

2018-06-06T21:17:53+00:00

Remove the verbose license text from XFS files and replace them
with SPDX tags. This does not change the license of any of the code,
merely refers to the common, up-to-date license files in LICENSES/

This change was mostly scripted. fs/xfs/Makefile and
fs/xfs/libxfs/xfs_fs.h were modified by hand, the rest were detected
and modified by the following command:

for f in `git grep -l "GNU General" fs/xfs/` ; do
	echo $f
	cat $f | awk -f hdr.awk > $f.new
	mv -f $f.new $f
done

And the hdr.awk script that did the modification (including
detecting the difference between GPL-2.0 and GPL-2.0+ licenses)
is as follows:

$ cat hdr.awk
BEGIN {
	hdr = 1.0
	tag = "GPL-2.0"
	str = ""
}

/^ \* This program is free software/ {
	hdr = 2.0;
	next
}

/any later version./ {
	tag = "GPL-2.0+"
	next
}

/^ \*\// {
	if (hdr > 0.0) {
		print "// SPDX-License-Identifier: " tag
		print str
		print $0
		str=""
		hdr = 0.0
		next
	}
	print $0
	next
}

/^ \* / {
	if (hdr > 1.0)
		next
	if (hdr > 0.0) {
		if (str != "")
			str = str "\n"
		str = str $0
		next
	}
	print $0
	next
}

/^ \*/ {
	if (hdr > 0.0)
		next
	print $0
	next
}

// {
	if (hdr > 0.0) {
		if (str != "")
			str = str "\n"
		str = str $0
		next
	}
	print $0
}

END { }
$

Signed-off-by: Dave Chinner 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong

xfs: fix xfs_rtalloc_rec units

2018-06-01T16:00:16+00:00

All the realtime allocation functions deal with space on the rtdev in
units of realtime extents.  However, struct xfs_rtalloc_rec confusingly
uses the word 'block' in the name, even though they're really extents.

Fix the naming problem and fix all the unit handling problems in the two
existing users.

Signed-off-by: Darrick J. Wong 
Reviewed-by: Allison Henderson 
Reviewed-by: Bill O'Donnell

xfs: cross-reference the realtime bitmap

2018-01-18T05:00:46+00:00

While we're scrubbing various btrees, cross-reference the records
with the other metadata.

Signed-off-by: Darrick J. Wong 
Reviewed-by: Dave Chinner

xfs: create block pointer check functions

2017-10-26T22:38:23+00:00

Create some helper functions to check that a block pointer points
within the filesystem (or AG) and doesn't point at static metadata.
We will use this for scrub.

Signed-off-by: Darrick J. Wong 
Reviewed-by: Dave Chinner

xfs: export various function for the online scrubber

2017-06-19T21:11:34+00:00

Export various internal functions so that the online scrubber can use
them to check the state of metadata.

Signed-off-by: Darrick J. Wong 
Reviewed-by: Brian Foster