linux/fs, branch v3.6

vfs: dcache: fix deadlock in tree traversal

2012-09-30T00:41:40Z

IBM reported a deadlock in select_parent(). This was found to be caused by taking rename_lock when already locked when restarting the tree traversal. There are two cases when the traversal needs to be restarted: 1) concurrent d_move(); this can only happen when not already locked, since taking rename_lock protects against concurrent d_move(). 2) racing with final d_put() on child just at the moment of ascending to parent; rename_lock doesn't protect against this rare race, so it can happen when already locked. Because of case 2, we need to be able to handle restarting the traversal when rename_lock is already held. This patch fixes all three callers of try_to_ascend(). IBM reported that the deadlock is gone with this patch. [ I rewrote the patch to be smaller and just do the "goto again" if the lock was already held, but credit goes to Miklos for the real work. - Linus ] Signed-off-by: Miklos Szeredi Cc: Al Viro Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds

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

2012-09-28T17:02:53Z

Pull vfs fixes from Al Viro: "A couple of fixes; one for automount/lazy umount race, another a classic "we don't protect the refcount transition to zero with the lock that protects looking for object in hash" kind of crap in lockd." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: close the race in nlmsvc_free_block() do_add_mount()/umount -l races

trivial select_parent documentation fix

2012-09-27T22:43:08Z

"Search list for X" sounds like you're trying to find X on a list. Signed-off-by: J. Bruce Fields Signed-off-by: Linus Torvalds

close the race in nlmsvc_free_block()

2012-09-23T00:48:20Z

we need to grab mutex before the reference counter reaches 0 Signed-off-by: Al Viro

do_add_mount()/umount -l races

2012-09-23T00:48:18Z

normally we deal with lock_mount()/umount races by checking that mountpoint to be is still in our namespace after lock_mount() has been done. However, do_add_mount() skips that check when called with MNT_SHRINKABLE in flags (i.e. from finish_automount()). The reason is that ->mnt_ns may be a temporary namespace created exactly to contain automounts a-la NFS4 referral handling. It's not the namespace of the caller, though, so check_mnt() would fail here. We still need to check that ->mnt_ns is non-NULL in that case, though. Signed-off-by: Al Viro

Merge branch 'for-linus' of git://git.samba.org/sfrench/cifs-2.6

2012-09-22T19:36:57Z

Pull cifs fix from Steve French. * 'for-linus' of git://git.samba.org/sfrench/cifs-2.6: cifs: fix return value in cifsConvertToUTF16

Merge tag 'for-linus-v3.6-rc7' of git://oss.sgi.com/xfs/xfs

2012-09-21T19:43:01Z

Pull xfs bugfixes from Ben Myers: - fix a regression related to xfs_sync_worker racing with unmount. - fix a race while discarding xfs buffers. * tag 'for-linus-v3.6-rc7' of git://oss.sgi.com/xfs/xfs: xfs: stop the sync worker before xfs_unmountfs xfs: fix race while discarding buffers [V4]

debugfs: fix u32_array race in format_array_alloc

2012-09-21T18:48:05Z

The format_array_alloc() function is fundamentally racy, in that it prints the array twice: once to figure out how much space to allocate for the buffer, and the second time to actually print out the data. If any of the array contents changes in between, the allocation size may be wrong, and the end result may be truncated in odd ways. Just don't do it. Allocate a maximum-sized array up-front, and just format the array contents once. The only user of the u32_array interfaces is the Xen spinlock statistics code, and it has 31 entries in the arrays, so the maximum size really isn't that big, and the end result is much simpler code without the bug. Signed-off-by: Linus Torvalds

debugfs: fix race in u32_array_read and allocate array at open

2012-09-21T17:28:17Z

u32_array_open() is racy when multiple threads read from a file with a seek position of zero, i.e. when two or more simultaneous reads are occurring after the non-seekable files are created. It is possible that file->private_data is double-freed because the threads races between kfree(file->private-data); and file->private_data = NULL; The fix is to only do format_array_alloc() when the file is opened and free it when it is closed. Note that because the file has always been non-seekable, you can't open it and read it multiple times anyway, so the data has always been generated just once. The difference is that now it is generated at open time rather than at the time of the first read, and that avoids the race. Reported-by: Dave Jones Acked-by: Konrad Rzeszutek Wilk Tested-by: Raghavendra Signed-off-by: David Rientjes Signed-off-by: Linus Torvalds

xfs: stop the sync worker before xfs_unmountfs

2012-09-18T21:51:26Z

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