linux-stable.git/fs/xfs, branch linux-3.6.y

xfs: drop buffer io reference when a bad bio is built

2012-11-26T20:14:05+00:00

commit d69043c42d8c6414fa28ad18d99973aa6c1c2e24 upstream.

Error handling in xfs_buf_ioapply_map() does not handle IO reference
counts correctly. We increment the b_io_remaining count before
building the bio, but then fail to decrement it in the failure case.
This leads to the buffer never running IO completion and releasing
the reference that the IO holds, so at unmount we can leak the
buffer. This leak is captured by this assert failure during unmount:

XFS: Assertion failed: atomic_read(&pag->pag_ref) == 0, file: fs/xfs/xfs_mount.c, line: 273

This is not a new bug - the b_io_remaining accounting has had this
problem for a long, long time - it's just very hard to get a
zero length bio being built by this code...

Further, the buffer IO error can be overwritten on a multi-segment
buffer by subsequent bio completions for partial sections of the
buffer. Hence we should only set the buffer error status if the
buffer is not already carrying an error status. This ensures that a
partial IO error on a multi-segment buffer will not be lost. This
part of the problem is a regression, however.

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

xfs: fix buffer shudown reference count mismatch

2012-11-17T21:19:06+00:00

commit 03b1293edad462ad1ad62bcc5160c76758e450d5 upstream.

When we shut down the filesystem, we have to unpin and free all the
buffers currently active in the CIL. To do this we unpin and remove
them in one operation as a result of a failed iclogbuf write. For
buffers, we do this removal via a simultated IO completion of after
marking the buffer stale.

At the time we do this, we have two references to the buffer - the
active LRU reference and the buf log item.  The LRU reference is
removed by marking the buffer stale, and the active CIL reference is
by the xfs_buf_iodone() callback that is run by
xfs_buf_do_callbacks() during ioend processing (via the bp->b_iodone
callback).

However, ioend processing requires one more reference - that of the
IO that it is completing. We don't have this reference, so we free
the buffer prematurely and use it after it is freed. For buffers
marked with XBF_ASYNC, this leads to assert failures in
xfs_buf_rele() on debug kernels because the b_hold count is zero.

Fix this by making sure we take the necessary IO reference before
starting IO completion processing on the stale buffer, and set the
XBF_ASYNC flag to ensure that IO completion processing removes all
the active references from the buffer to ensure it is fully torn
down.

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

xfs: fix reading of wrapped log data

2012-11-17T21:19:06+00:00

commit 6ce377afd1755eae5c93410ca9a1121dfead7b87 upstream.

Commit 4439647 ("xfs: reset buffer pointers before freeing them") in
3.0-rc1 introduced a regression when recovering log buffers that
wrapped around the end of log. The second part of the log buffer at
the start of the physical log was being read into the header buffer
rather than the data buffer, and hence recovery was seeing garbage
in the data buffer when it got to the region of the log buffer that
was incorrectly read.

Reported-by: Torsten Kaiser 
Signed-off-by: Dave Chinner 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Mark Tinguely 
Signed-off-by: Ben Myers 
Signed-off-by: Greg Kroah-Hartman

tmpfs,ceph,gfs2,isofs,reiserfs,xfs: fix fh_len checking

2012-10-21T16:32:39+00:00

commit 35c2a7f4908d404c9124c2efc6ada4640ca4d5d5 upstream.

Fuzzing with trinity oopsed on the 1st instruction of shmem_fh_to_dentry(),
	u64 inum = fid->raw[2];
which is unhelpfully reported as at the end of shmem_alloc_inode():

BUG: unable to handle kernel paging request at ffff880061cd3000
IP: [] shmem_alloc_inode+0x40/0x40
Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
Call Trace:
 [] ? exportfs_decode_fh+0x79/0x2d0
 [] do_handle_open+0x163/0x2c0
 [] sys_open_by_handle_at+0xc/0x10
 [] tracesys+0xe1/0xe6

Right, tmpfs is being stupid to access fid->raw[2] before validating that
fh_len includes it: the buffer kmalloc'ed by do_sys_name_to_handle() may
fall at the end of a page, and the next page not be present.

But some other filesystems (ceph, gfs2, isofs, reiserfs, xfs) are being
careless about fh_len too, in fh_to_dentry() and/or fh_to_parent(), and
could oops in the same way: add the missing fh_len checks to those.

Reported-by: Sasha Levin 
Signed-off-by: Hugh Dickins 
Cc: Al Viro 
Cc: Sage Weil 
Cc: Steven Whitehouse 
Cc: Christoph Hellwig 
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

xfs: stop the sync worker before xfs_unmountfs

2012-09-18T21:51:26+00:00

Cancel work of the xfs_sync_worker before teardown of the log in
xfs_unmountfs.  This prevents occasional crashes on unmount like so:

PID: 21602  TASK: ee9df060  CPU: 0   COMMAND: "kworker/0:3"
 #0 [c5377d28] crash_kexec at c0292c94
 #1 [c5377d80] oops_end at c07090c2
 #2 [c5377d98] no_context at c06f614e
 #3 [c5377dbc] __bad_area_nosemaphore at c06f6281
 #4 [c5377df4] bad_area_nosemaphore at c06f629b
 #5 [c5377e00] do_page_fault at c070b0cb
 #6 [c5377e7c] error_code (via page_fault) at c070892c
    EAX: f300c6a8  EBX: f300c6a8  ECX: 000000c0  EDX: 000000c0  EBP: c5377ed0
    DS:  007b      ESI: 00000000  ES:  007b      EDI: 00000001  GS:  ffffad20
    CS:  0060      EIP: c0481ad0  ERR: ffffffff  EFLAGS: 00010246
 #7 [c5377eb0] atomic64_read_cx8 at c0481ad0
 #8 [c5377ebc] xlog_assign_tail_lsn_locked at f7cc7c6e [xfs]
 #9 [c5377ed4] xfs_trans_ail_delete_bulk at f7ccd520 [xfs]
#10 [c5377f0c] xfs_buf_iodone at f7ccb602 [xfs]
#11 [c5377f24] xfs_buf_do_callbacks at f7cca524 [xfs]
#12 [c5377f30] xfs_buf_iodone_callbacks at f7cca5da [xfs]
#13 [c5377f4c] xfs_buf_iodone_work at f7c718d0 [xfs]
#14 [c5377f58] process_one_work at c024ee4c
#15 [c5377f98] worker_thread at c024f43d
#16 [c5377fbc] kthread at c025326b
#17 [c5377fe8] kernel_thread_helper at c070e834

PID: 26653  TASK: e79143b0  CPU: 3   COMMAND: "umount"
 #0 [cde0fda0] __schedule at c0706595
 #1 [cde0fe28] schedule at c0706b89
 #2 [cde0fe30] schedule_timeout at c0705600
 #3 [cde0fe94] __down_common at c0706098
 #4 [cde0fec8] __down at c0706122
 #5 [cde0fed0] down at c025936f
 #6 [cde0fee0] xfs_buf_lock at f7c7131d [xfs]
 #7 [cde0ff00] xfs_freesb at f7cc2236 [xfs]
 #8 [cde0ff10] xfs_fs_put_super at f7c80f21 [xfs]
 #9 [cde0ff1c] generic_shutdown_super at c0333d7a
#10 [cde0ff38] kill_block_super at c0333e0f
#11 [cde0ff48] deactivate_locked_super at c0334218
#12 [cde0ff58] deactivate_super at c033495d
#13 [cde0ff68] mntput_no_expire at c034bc13
#14 [cde0ff7c] sys_umount at c034cc69
#15 [cde0ffa0] sys_oldumount at c034ccd4
#16 [cde0ffb0] system_call at c0707e66

commit 11159a05 added this to xfs_log_unmount and needs to be cleaned up
at a later date.

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

xfs: fix race while discarding buffers [V4]

2012-08-29T20:01:11+00:00

While xfs_buftarg_shrink() is freeing buffers from the dispose list (filled with
buffers from lru list), there is a possibility to have xfs_buf_stale() racing
with it, and removing buffers from dispose list before xfs_buftarg_shrink() does
it.

This happens because xfs_buftarg_shrink() handle the dispose list without
locking and the test condition in xfs_buf_stale() checks for the buffer being in
*any* list:

if (!list_empty(&bp->b_lru))

If the buffer happens to be on dispose list, this causes the buffer counter of
lru list (btp->bt_lru_nr) to be decremented twice (once in xfs_buftarg_shrink()
and another in xfs_buf_stale()) causing a wrong account usage of the lru list.

This may cause xfs_buftarg_shrink() to return a wrong value to the memory
shrinker shrink_slab(), and such account error may also cause an underflowed
value to be returned; since the counter is lower than the current number of
items in the lru list, a decrement may happen when the counter is 0, causing
an underflow on the counter.

The fix uses a new flag field (and a new buffer flag) to serialize buffer
handling during the shrink process. The new flag field has been designed to use
btp->bt_lru_lock/unlock instead of xfs_buf_lock/unlock mechanism.

dchinner, sandeen, aquini and aris also deserve credits for this.

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

xfs: check for possible overflow in xfs_ioc_trim

2012-08-23T19:48:44+00:00

If range.start or range.minlen is bigger than filesystem size, return
invalid value error. This fixes possible overflow in BTOBB macro when
passed value was nearly ULLONG_MAX.

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

xfs: unlock the AGI buffer when looping in xfs_dialloc

2012-08-23T19:48:32+00:00

Also update some commens in the area to make the code easier to read.

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

xfs: fix uninitialised variable in xfs_rtbuf_get()

2012-08-23T19:48:16+00:00

Results in this assert failure in generic/090:

XFS: Assertion failed: *nmap >= 1, file: fs/xfs/xfs_bmap.c, line: 4363
.....
Call Trace:
 [] xfs_bmapi_read+0x6b/0x370
 [] xfs_rtbuf_get+0x42/0x130
 [] xfs_rtget_summary+0x89/0x120
 [] xfs_rtallocate_extent_size+0xce/0x340
 [] xfs_rtallocate_extent+0x240/0x290
 [] xfs_bmap_rtalloc+0x1ba/0x340
 [] xfs_bmap_alloc+0x35/0x40
 [] xfs_bmapi_allocate+0xf1/0x350
 [] xfs_bmapi_write+0x66e/0xa60
 [] xfs_iomap_write_direct+0x22a/0x3f0
 [] __xfs_get_blocks+0x38b/0x5d0
 [] xfs_get_blocks_direct+0x14/0x20
 [] do_blockdev_direct_IO+0xf71/0x1eb0
 [] __blockdev_direct_IO+0x55/0x60
 [] xfs_vm_direct_IO+0x11a/0x1e0
 [] generic_file_direct_write+0xd7/0x1b0
 [] xfs_file_dio_aio_write+0x13c/0x320
 [] xfs_file_aio_write+0x1c2/0x1d0
 [] do_sync_write+0xa7/0xe0
 [] vfs_write+0xa8/0x160
 [] sys_pwrite64+0x92/0xb0
 [] system_call_fastpath+0x16/0x1b

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

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2012-08-01T17:26:23+00:00

Pull second vfs pile from Al Viro:
 "The stuff in there: fsfreeze deadlock fixes by Jan (essentially, the
  deadlock reproduced by xfstests 068), symlink and hardlink restriction
  patches, plus assorted cleanups and fixes.

  Note that another fsfreeze deadlock (emergency thaw one) is *not*
  dealt with - the series by Fernando conflicts a lot with Jan's, breaks
  userland ABI (FIFREEZE semantics gets changed) and trades the deadlock
  for massive vfsmount leak; this is going to be handled next cycle.
  There probably will be another pull request, but that stuff won't be
  in it."

Fix up trivial conflicts due to unrelated changes next to each other in
drivers/{staging/gdm72xx/usb_boot.c, usb/gadget/storage_common.c}

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (54 commits)
  delousing target_core_file a bit
  Documentation: Correct s_umount state for freeze_fs/unfreeze_fs
  fs: Remove old freezing mechanism
  ext2: Implement freezing
  btrfs: Convert to new freezing mechanism
  nilfs2: Convert to new freezing mechanism
  ntfs: Convert to new freezing mechanism
  fuse: Convert to new freezing mechanism
  gfs2: Convert to new freezing mechanism
  ocfs2: Convert to new freezing mechanism
  xfs: Convert to new freezing code
  ext4: Convert to new freezing mechanism
  fs: Protect write paths by sb_start_write - sb_end_write
  fs: Skip atime update on frozen filesystem
  fs: Add freezing handling to mnt_want_write() / mnt_drop_write()
  fs: Improve filesystem freezing handling
  switch the protection of percpu_counter list to spinlock
  nfsd: Push mnt_want_write() outside of i_mutex
  btrfs: Push mnt_want_write() outside of i_mutex
  fat: Push mnt_want_write() outside of i_mutex
  ...