New code for 5.15:
 - Fix a potential log livelock on busy filesystems when there's so much
   work going on that we can't finish a quotaoff before filling up the log
   by removing the ability to disable quota accounting.
 - Introduce the ability to use per-CPU data structures in XFS so that
   we can do a better job of maintaining CPU locality for certain
 - Defer inode inactivation work to per-CPU lists, which will help us
   batch that processing.  Deletions of large sparse files will *appear*
   to run faster, but all that means is that we've moved the work to the
 - Drop the EXPERIMENTAL warnings from the y2038+ support and the inode
   btree counters, since it's been nearly a year and no complaints have
   come in.
 - Remove more of our bespoke kmem* variants in favor of using the
   standard Linux calls.
 - Prepare for the addition of log incompat features in upcoming cycles
   by actually adding code to support this.
 - Small cleanups of the xattr code in preparation for landing support
   for full logging of extended attribute updates in a future cycle.
 - Replace the various log shutdown state and flag code all over xfs
   with a single atomic bit flag.
 - Fix a serious log recovery bug where log item replay can be skipped
   based on the start lsn of a transaction even though the transaction
   commit lsn is the key data point for that by enforcing start lsns to
   appear in the log in the same order as commit lsns.
 - Enable pipelining in the code that pushes log items to disk.
 - Drop ->writepage.
 - Fix some bugs in GETFSMAP where the last fsmap record reported for a
   device could extend beyond the end of the device, and a separate bug
   where query keys for one device could be applied to another.
 - Don't let GETFSMAP query functions edit their input parameters.
 - Small cleanups to the scrub code's handling of perag structures.
 - Small cleanups to the incore inode tree walk code.
 - Constify btree function parameters that aren't changed, so that there
   will never again be confusion about range query functions changing
   their input parameters.
 - Standardize the format and names of tracepoint data attributes.
 - Clean up all the mount state and feature flags to use wrapped bitset
   functions instead of inconsistently open-coded flag checks.
 - Fix some confusion between xfs_buf hash table key variable vs. block
xfs: fix perag structure refcounting error when scrub fails

The kernel test robot found the following bug when running xfs/355 to
scrub a bmap btree:

XFS: Assertion failed: !sa->pag, file: fs/xfs/scrub/common.c, line: 412
------------[ cut here ]------------
kernel BUG at fs/xfs/xfs_message.c:110!
invalid opcode: 0000 [#1] SMP PTI
CPU: 2 PID: 1415 Comm: xfs_scrub Not tainted 5.14.0-rc4-00021-g48c6615cc557 #1
Hardware name: Hewlett-Packard p6-1451cx/2ADA, BIOS 8.15 02/05/2013
RIP: 0010:assfail+0x23/0x28 [xfs]
RSP: 0018:ffffc9000aacb890 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffffc9000aacbcc8 RCX: 0000000000000000
RDX: 00000000ffffffc0 RSI: 000000000000000a RDI: ffffffffc09e7dcd
RBP: ffffc9000aacbc80 R08: ffff8881fdf17d50 R09: 0000000000000000
R10: 000000000000000a R11: f000000000000000 R12: 0000000000000000
R13: ffff88820c7ed000 R14: 0000000000000001 R15: ffffc9000aacb980
FS:  00007f185b955700(0000) GS:ffff8881fdf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7f6ef43000 CR3: 000000020de38002 CR4: 00000000001706e0
Call Trace:
 xchk_ag_read_headers+0xda/0x100 [xfs]
 xchk_ag_init+0x15/0x40 [xfs]
 xchk_btree_check_block_owner+0x76/0x180 [xfs]
 xchk_btree_get_block+0xd0/0x140 [xfs]
 xchk_btree+0x32e/0x440 [xfs]
 xchk_bmap_btree+0xd4/0x140 [xfs]
 xchk_bmap+0x1eb/0x3c0 [xfs]
 xfs_scrub_metadata+0x227/0x4c0 [xfs]
 xfs_ioc_scrub_metadata+0x50/0xc0 [xfs]
 xfs_file_ioctl+0x90c/0xc40 [xfs]

The unusual handling of errors while initializing struct xchk_ag is the
root cause here.  Since the beginning of xfs_scrub, the goal of
xchk_ag_read_headers has been to read all three AG header buffers and
attach them both to the xchk_ag structure and the scrub transaction.
Corruption errors on any of the three headers doesn't necessarily
trigger an immediate return to userspace, because xfs_scrub can also
tell us to /fix/ the problem.

In other words, it's possible for the xchk_ag init functions to return
an error code and a partially filled out structure so that scrub can use
however much information it managed to pull.  Before 5.15, it was
sufficient to cancel (or commit) the scrub transaction on the way out of
the scrub code to release the buffers.

Ccommit 48c6615cc557 added a reference to the perag structure to struct
xchk_ag.  Since perag structures are not attached to transactions like
buffers are, this adds the requirement that the perag ref be released
explicitly.  The scrub teardown function xchk_teardown was amended to do
this for the xchk_ag embedded in struct xfs_scrub.

Unfortunately, I forgot that certain parts of the scrub code probe
multiple AGs and therefore handle the initialization and cleanup on
their own.  Specifically, the bmbt scrubber will initialize it long
enough to cross-reference AG metadata for btree blocks and for the
extent mappings in the bmbt.

If one of the AG headers is corrupt, the init function returns with a
live perag structure reference and some of the AG header buffers.  If an
error occurs, the cross referencing will be noted as XCORRUPTion and
skipped, but the main scrub process will move on to the next record.
It is now necessary to release the perag reference before we try to
analyze something from a different AG, or else we'll trip over the
assertion noted above.

Fixes: 48c6615cc557 ("xfs: grab active perag ref when reading AG headers")
Reported-by: kernel test robot <>
Signed-off-by: Darrick J. Wong <>
Reviewed-by: Chandan Babu R <>
4 files changed