linux-toradex.git/fs/btrfs/tree-log.c, branch v5.0 Linux kernel for Apalis and Colibri modules btrfs: Fix typos in comments and strings 2018-12-17T13:51:50+00:00 Andrea Gelmini andrea.gelmini@gelma.net 2018-11-28T11:05:13+00:00 52042d8e82ff50d40e76a275ac0b97aa663328b0 The typos accumulate over time so once in a while time they get fixed in a large patch. Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> 
The typos accumulate over time so once in a while time they get fixed in
a large patch.

Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Btrfs: fix fsync of files with multiple hard links in new directories 2018-12-17T13:51:43+00:00 Filipe Manana fdmanana@suse.com 2018-11-28T14:54:28+00:00 41bd60676923822de1df2c50b3f9a10171f4338a The log tree has a long standing problem that when a file is fsync'ed we only check for new ancestors, created in the current transaction, by following only the hard link for which the fsync was issued. We follow the ancestors using the VFS' dget_parent() API. This means that if we create a new link for a file in a directory that is new (or in an any other new ancestor directory) and then fsync the file using an old hard link, we end up not logging the new ancestor, and on log replay that new hard link and ancestor do not exist. In some cases, involving renames, the file will not exist at all. Example: mkfs.btrfs -f /dev/sdb mount /dev/sdb /mnt mkdir /mnt/A touch /mnt/foo ln /mnt/foo /mnt/A/bar xfs_io -c fsync /mnt/foo <power failure> In this example after log replay only the hard link named 'foo' exists and directory A does not exist, which is unexpected. In other major linux filesystems, such as ext4, xfs and f2fs for example, both hard links exist and so does directory A after mounting again the filesystem. Checking if any new ancestors are new and need to be logged was added in 2009 by commit 12fcfd22fe5b ("Btrfs: tree logging unlink/rename fixes"), however only for the ancestors of the hard link (dentry) for which the fsync was issued, instead of checking for all ancestors for all of the inode's hard links. So fix this by tracking the id of the last transaction where a hard link was created for an inode and then on fsync fallback to a full transaction commit when an inode has more than one hard link and at least one new hard link was created in the current transaction. This is the simplest solution since this is not a common use case (adding frequently hard links for which there's an ancestor created in the current transaction and then fsync the file). In case it ever becomes a common use case, a solution that consists of iterating the fs/subvol btree for each hard link and check if any ancestor is new, could be implemented. This solves many unexpected scenarios reported by Jayashree Mohan and Vijay Chidambaram, and for which there is a new test case for fstests under review. Fixes: 12fcfd22fe5b ("Btrfs: tree logging unlink/rename fixes") CC: stable@vger.kernel.org # 4.4+ Reported-by: Vijay Chidambaram <vvijay03@gmail.com> Reported-by: Jayashree Mohan <jayashree2912@gmail.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> 
The log tree has a long standing problem that when a file is fsync'ed we
only check for new ancestors, created in the current transaction, by
following only the hard link for which the fsync was issued. We follow the
ancestors using the VFS' dget_parent() API. This means that if we create a
new link for a file in a directory that is new (or in an any other new
ancestor directory) and then fsync the file using an old hard link, we end
up not logging the new ancestor, and on log replay that new hard link and
ancestor do not exist. In some cases, involving renames, the file will not
exist at all.

Example:

  mkfs.btrfs -f /dev/sdb
  mount /dev/sdb /mnt

  mkdir /mnt/A
  touch /mnt/foo
  ln /mnt/foo /mnt/A/bar
  xfs_io -c fsync /mnt/foo

  <power failure>

In this example after log replay only the hard link named 'foo' exists
and directory A does not exist, which is unexpected. In other major linux
filesystems, such as ext4, xfs and f2fs for example, both hard links exist
and so does directory A after mounting again the filesystem.

Checking if any new ancestors are new and need to be logged was added in
2009 by commit 12fcfd22fe5b ("Btrfs: tree logging unlink/rename fixes"),
however only for the ancestors of the hard link (dentry) for which the
fsync was issued, instead of checking for all ancestors for all of the
inode's hard links.

So fix this by tracking the id of the last transaction where a hard link
was created for an inode and then on fsync fallback to a full transaction
commit when an inode has more than one hard link and at least one new hard
link was created in the current transaction. This is the simplest solution
since this is not a common use case (adding frequently hard links for
which there's an ancestor created in the current transaction and then
fsync the file). In case it ever becomes a common use case, a solution
that consists of iterating the fs/subvol btree for each hard link and
check if any ancestor is new, could be implemented.

This solves many unexpected scenarios reported by Jayashree Mohan and
Vijay Chidambaram, and for which there is a new test case for fstests
under review.

Fixes: 12fcfd22fe5b ("Btrfs: tree logging unlink/rename fixes")
CC: stable@vger.kernel.org # 4.4+
Reported-by: Vijay Chidambaram <vvijay03@gmail.com>
Reported-by: Jayashree Mohan <jayashree2912@gmail.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Btrfs: simpler and more efficient cleanup of a log tree's extent io tree 2018-12-17T13:51:31+00:00 Filipe Manana fdmanana@suse.com 2018-11-09T10:43:08+00:00 59b0713a8a6c0f72ab468507dcd6b866869b900a We currently are in a loop finding each range (corresponding to a btree node/leaf) in a log root's extent io tree and then clean it up. This is a waste of time since we are traversing the extent io tree's rb_tree more times then needed (one for a range lookup and another for cleaning it up) without any good reason. We free the log trees when we are in the critical section of a transaction commit (the transaction state is set to TRANS_STATE_COMMIT_DOING), so it's of great convenience to do everything as fast as possible in order to reduce the time we block other tasks from starting a new transaction. So fix this by traversing the extent io tree once and cleaning up all its records in one go while traversing it. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> 
We currently are in a loop finding each range (corresponding to a btree
node/leaf) in a log root's extent io tree and then clean it up. This is a
waste of time since we are traversing the extent io tree's rb_tree more
times then needed (one for a range lookup and another for cleaning it up)
without any good reason.

We free the log trees when we are in the critical section of a transaction
commit (the transaction state is set to TRANS_STATE_COMMIT_DOING), so it's
of great convenience to do everything as fast as possible in order to
reduce the time we block other tasks from starting a new transaction.

So fix this by traversing the extent io tree once and cleaning up all its
records in one go while traversing it.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Btrfs: remove no longer used logged range variables when logging extents 2018-12-17T13:51:25+00:00 Filipe Manana fdmanana@suse.com 2018-10-26T20:26:40+00:00 ce02f0326680562a905216d6601c8ac5020feaba The logged_start and logged_end variables, at btrfs_log_changed_extents, were added in commit 8c6c592831a0 ("btrfs: log csums for all modified extents"). However since the recent simplification for fsync, which makes us wait for all ordered extents to complete before logging extents, we no longer need those variables. Commit a2120a473a80 ("btrfs: clean up the left over logged_list usage") forgot to remove them. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> 
The logged_start and logged_end variables, at btrfs_log_changed_extents,
were added in commit 8c6c592831a0 ("btrfs: log csums for all modified
extents"). However since the recent simplification for fsync, which makes
us wait for all ordered extents to complete before logging extents, we
no longer need those variables. Commit a2120a473a80 ("btrfs: clean up the
left over logged_list usage") forgot to remove them.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Btrfs: fix missing data checksums after a ranged fsync (msync) 2018-11-06T15:41:40+00:00 Filipe Manana fdmanana@suse.com 2018-10-29T09:42:06+00:00 008c6753f7e070c77c70d708a6bf0255b4381763 Recently we got a massive simplification for fsync, where for the fast path we no longer log new extents while their respective ordered extents are still running. However that simplification introduced a subtle regression for the case where we use a ranged fsync (msync). Consider the following example: CPU 0 CPU 1 mmap write to range [2Mb, 4Mb[ mmap write to range [512Kb, 1Mb[ msync range [512K, 1Mb[ --> triggers fast fsync (BTRFS_INODE_NEEDS_FULL_SYNC not set) --> creates extent map A for this range and adds it to list of modified extents --> starts ordered extent A for this range --> waits for it to complete writeback triggered for range [2Mb, 4Mb[ --> create extent map B and adds it to the list of modified extents --> creates ordered extent B --> start looking for and logging modified extents --> logs extent maps A and B --> finds checksums for extent A in the csum tree, but not for extent B fsync (msync) finishes --> ordered extent B finishes and its checksums are added to the csum tree <power cut> After replaying the log, we have the extent covering the range [2Mb, 4Mb[ but do not have the data checksum items covering that file range. This happens because at the very beginning of an fsync (btrfs_sync_file()) we start and wait for IO in the given range [512Kb, 1Mb[ and therefore wait for any ordered extents in that range to complete before we start logging the extents. However if right before we start logging the extent in our range [512Kb, 1Mb[, writeback is started for any other dirty range, such as the range [2Mb, 4Mb[ due to memory pressure or a concurrent fsync or msync (btrfs_sync_file() starts writeback before acquiring the inode's lock), an ordered extent is created for that other range and a new extent map is created to represent that range and added to the inode's list of modified extents. That means that we will see that other extent in that list when collecting extents for logging (done at btrfs_log_changed_extents()) and log the extent before the respective ordered extent finishes - namely before the checksum items are added to the checksums tree, which is where log_extent_csums() looks for the checksums, therefore making us log an extent without logging its checksums. Before that massive simplification of fsync, this wasn't a problem because besides looking for checkums in the checksums tree, we also looked for them in any ordered extent still running. The consequence of data checksums missing for a file range is that users attempting to read the affected file range will get -EIO errors and dmesg reports the following: [10188.358136] BTRFS info (device sdc): no csum found for inode 297 start 57344 [10188.359278] BTRFS warning (device sdc): csum failed root 5 ino 297 off 57344 csum 0x98f94189 expected csum 0x00000000 mirror 1 So fix this by skipping extents outside of our logging range at btrfs_log_changed_extents() and leaving them on the list of modified extents so that any subsequent ranged fsync may collect them if needed. Also, if we find a hole extent outside of the range still log it, just to prevent having gaps between extent items after replaying the log, otherwise fsck will complain when we are not using the NO_HOLES feature (fstest btrfs/056 triggers such case). Fixes: e7175a692765 ("btrfs: remove the wait ordered logic in the log_one_extent path") CC: stable@vger.kernel.org # 4.19+ Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> 
Recently we got a massive simplification for fsync, where for the fast
path we no longer log new extents while their respective ordered extents
are still running.

However that simplification introduced a subtle regression for the case
where we use a ranged fsync (msync). Consider the following example:

               CPU 0                                    CPU 1

                                            mmap write to range [2Mb, 4Mb[
  mmap write to range [512Kb, 1Mb[
  msync range [512K, 1Mb[
    --> triggers fast fsync
        (BTRFS_INODE_NEEDS_FULL_SYNC
         not set)
    --> creates extent map A for this
        range and adds it to list of
        modified extents
    --> starts ordered extent A for
        this range
    --> waits for it to complete

                                            writeback triggered for range
                                            [2Mb, 4Mb[
                                              --> create extent map B and
                                                  adds it to the list of
                                                  modified extents
                                              --> creates ordered extent B

    --> start looking for and logging
        modified extents
    --> logs extent maps A and B
    --> finds checksums for extent A
        in the csum tree, but not for
        extent B
  fsync (msync) finishes

                                              --> ordered extent B
                                                  finishes and its
                                                  checksums are added
                                                  to the csum tree

                                <power cut>

After replaying the log, we have the extent covering the range [2Mb, 4Mb[
but do not have the data checksum items covering that file range.

This happens because at the very beginning of an fsync (btrfs_sync_file())
we start and wait for IO in the given range [512Kb, 1Mb[ and therefore
wait for any ordered extents in that range to complete before we start
logging the extents. However if right before we start logging the extent
in our range [512Kb, 1Mb[, writeback is started for any other dirty range,
such as the range [2Mb, 4Mb[ due to memory pressure or a concurrent fsync
or msync (btrfs_sync_file() starts writeback before acquiring the inode's
lock), an ordered extent is created for that other range and a new extent
map is created to represent that range and added to the inode's list of
modified extents.

That means that we will see that other extent in that list when collecting
extents for logging (done at btrfs_log_changed_extents()) and log the
extent before the respective ordered extent finishes - namely before the
checksum items are added to the checksums tree, which is where
log_extent_csums() looks for the checksums, therefore making us log an
extent without logging its checksums. Before that massive simplification
of fsync, this wasn't a problem because besides looking for checkums in
the checksums tree, we also looked for them in any ordered extent still
running.

The consequence of data checksums missing for a file range is that users
attempting to read the affected file range will get -EIO errors and dmesg
reports the following:

 [10188.358136] BTRFS info (device sdc): no csum found for inode 297 start 57344
 [10188.359278] BTRFS warning (device sdc): csum failed root 5 ino 297 off 57344 csum 0x98f94189 expected csum 0x00000000 mirror 1

So fix this by skipping extents outside of our logging range at
btrfs_log_changed_extents() and leaving them on the list of modified
extents so that any subsequent ranged fsync may collect them if needed.
Also, if we find a hole extent outside of the range still log it, just
to prevent having gaps between extent items after replaying the log,
otherwise fsck will complain when we are not using the NO_HOLES feature
(fstest btrfs/056 triggers such case).

Fixes: e7175a692765 ("btrfs: remove the wait ordered logic in the log_one_extent path")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: move the dio_sem higher up the callchain 2018-10-19T10:20:04+00:00 Josef Bacik josef@toxicpanda.com 2018-10-12T19:32:32+00:00 c495144bc6962186feae31d687596d2472000e45 We're getting a lockdep splat because we take the dio_sem under the log_mutex. What we really need is to protect fsync() from logging an extent map for an extent we never waited on higher up, so just guard the whole thing with dio_sem. ====================================================== WARNING: possible circular locking dependency detected 4.18.0-rc4-xfstests-00025-g5de5edbaf1d4 #411 Not tainted ------------------------------------------------------ aio-dio-invalid/30928 is trying to acquire lock: 0000000092621cfd (&mm->mmap_sem){++++}, at: get_user_pages_unlocked+0x5a/0x1e0 but task is already holding lock: 00000000cefe6b35 (&ei->dio_sem){++++}, at: btrfs_direct_IO+0x3be/0x400 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&ei->dio_sem){++++}: lock_acquire+0xbd/0x220 down_write+0x51/0xb0 btrfs_log_changed_extents+0x80/0xa40 btrfs_log_inode+0xbaf/0x1000 btrfs_log_inode_parent+0x26f/0xa80 btrfs_log_dentry_safe+0x50/0x70 btrfs_sync_file+0x357/0x540 do_fsync+0x38/0x60 __ia32_sys_fdatasync+0x12/0x20 do_fast_syscall_32+0x9a/0x2f0 entry_SYSENTER_compat+0x84/0x96 -> #4 (&ei->log_mutex){+.+.}: lock_acquire+0xbd/0x220 __mutex_lock+0x86/0xa10 btrfs_record_unlink_dir+0x2a/0xa0 btrfs_unlink+0x5a/0xc0 vfs_unlink+0xb1/0x1a0 do_unlinkat+0x264/0x2b0 do_fast_syscall_32+0x9a/0x2f0 entry_SYSENTER_compat+0x84/0x96 -> #3 (sb_internal#2){.+.+}: lock_acquire+0xbd/0x220 __sb_start_write+0x14d/0x230 start_transaction+0x3e6/0x590 btrfs_evict_inode+0x475/0x640 evict+0xbf/0x1b0 btrfs_run_delayed_iputs+0x6c/0x90 cleaner_kthread+0x124/0x1a0 kthread+0x106/0x140 ret_from_fork+0x3a/0x50 -> #2 (&fs_info->cleaner_delayed_iput_mutex){+.+.}: lock_acquire+0xbd/0x220 __mutex_lock+0x86/0xa10 btrfs_alloc_data_chunk_ondemand+0x197/0x530 btrfs_check_data_free_space+0x4c/0x90 btrfs_delalloc_reserve_space+0x20/0x60 btrfs_page_mkwrite+0x87/0x520 do_page_mkwrite+0x31/0xa0 __handle_mm_fault+0x799/0xb00 handle_mm_fault+0x7c/0xe0 __do_page_fault+0x1d3/0x4a0 async_page_fault+0x1e/0x30 -> #1 (sb_pagefaults){.+.+}: lock_acquire+0xbd/0x220 __sb_start_write+0x14d/0x230 btrfs_page_mkwrite+0x6a/0x520 do_page_mkwrite+0x31/0xa0 __handle_mm_fault+0x799/0xb00 handle_mm_fault+0x7c/0xe0 __do_page_fault+0x1d3/0x4a0 async_page_fault+0x1e/0x30 -> #0 (&mm->mmap_sem){++++}: __lock_acquire+0x42e/0x7a0 lock_acquire+0xbd/0x220 down_read+0x48/0xb0 get_user_pages_unlocked+0x5a/0x1e0 get_user_pages_fast+0xa4/0x150 iov_iter_get_pages+0xc3/0x340 do_direct_IO+0xf93/0x1d70 __blockdev_direct_IO+0x32d/0x1c20 btrfs_direct_IO+0x227/0x400 generic_file_direct_write+0xcf/0x180 btrfs_file_write_iter+0x308/0x58c aio_write+0xf8/0x1d0 io_submit_one+0x3a9/0x620 __ia32_compat_sys_io_submit+0xb2/0x270 do_int80_syscall_32+0x5b/0x1a0 entry_INT80_compat+0x88/0xa0 other info that might help us debug this: Chain exists of: &mm->mmap_sem --> &ei->log_mutex --> &ei->dio_sem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ei->dio_sem); lock(&ei->log_mutex); lock(&ei->dio_sem); lock(&mm->mmap_sem); *** DEADLOCK *** 1 lock held by aio-dio-invalid/30928: #0: 00000000cefe6b35 (&ei->dio_sem){++++}, at: btrfs_direct_IO+0x3be/0x400 stack backtrace: CPU: 0 PID: 30928 Comm: aio-dio-invalid Not tainted 4.18.0-rc4-xfstests-00025-g5de5edbaf1d4 #411 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 Call Trace: dump_stack+0x7c/0xbb print_circular_bug.isra.37+0x297/0x2a4 check_prev_add.constprop.45+0x781/0x7a0 ? __lock_acquire+0x42e/0x7a0 validate_chain.isra.41+0x7f0/0xb00 __lock_acquire+0x42e/0x7a0 lock_acquire+0xbd/0x220 ? get_user_pages_unlocked+0x5a/0x1e0 down_read+0x48/0xb0 ? get_user_pages_unlocked+0x5a/0x1e0 get_user_pages_unlocked+0x5a/0x1e0 get_user_pages_fast+0xa4/0x150 iov_iter_get_pages+0xc3/0x340 do_direct_IO+0xf93/0x1d70 ? __alloc_workqueue_key+0x358/0x490 ? __blockdev_direct_IO+0x14b/0x1c20 __blockdev_direct_IO+0x32d/0x1c20 ? btrfs_run_delalloc_work+0x40/0x40 ? can_nocow_extent+0x490/0x490 ? kvm_clock_read+0x1f/0x30 ? can_nocow_extent+0x490/0x490 ? btrfs_run_delalloc_work+0x40/0x40 btrfs_direct_IO+0x227/0x400 ? btrfs_run_delalloc_work+0x40/0x40 generic_file_direct_write+0xcf/0x180 btrfs_file_write_iter+0x308/0x58c aio_write+0xf8/0x1d0 ? kvm_clock_read+0x1f/0x30 ? __might_fault+0x3e/0x90 io_submit_one+0x3a9/0x620 ? io_submit_one+0xe5/0x620 __ia32_compat_sys_io_submit+0xb2/0x270 do_int80_syscall_32+0x5b/0x1a0 entry_INT80_compat+0x88/0xa0 CC: stable@vger.kernel.org # 4.14+ Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com> 
We're getting a lockdep splat because we take the dio_sem under the
log_mutex.  What we really need is to protect fsync() from logging an
extent map for an extent we never waited on higher up, so just guard the
whole thing with dio_sem.

======================================================
WARNING: possible circular locking dependency detected
4.18.0-rc4-xfstests-00025-g5de5edbaf1d4 #411 Not tainted
------------------------------------------------------
aio-dio-invalid/30928 is trying to acquire lock:
0000000092621cfd (&mm->mmap_sem){++++}, at: get_user_pages_unlocked+0x5a/0x1e0

but task is already holding lock:
00000000cefe6b35 (&ei->dio_sem){++++}, at: btrfs_direct_IO+0x3be/0x400

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #5 (&ei->dio_sem){++++}:
       lock_acquire+0xbd/0x220
       down_write+0x51/0xb0
       btrfs_log_changed_extents+0x80/0xa40
       btrfs_log_inode+0xbaf/0x1000
       btrfs_log_inode_parent+0x26f/0xa80
       btrfs_log_dentry_safe+0x50/0x70
       btrfs_sync_file+0x357/0x540
       do_fsync+0x38/0x60
       __ia32_sys_fdatasync+0x12/0x20
       do_fast_syscall_32+0x9a/0x2f0
       entry_SYSENTER_compat+0x84/0x96

-> #4 (&ei->log_mutex){+.+.}:
       lock_acquire+0xbd/0x220
       __mutex_lock+0x86/0xa10
       btrfs_record_unlink_dir+0x2a/0xa0
       btrfs_unlink+0x5a/0xc0
       vfs_unlink+0xb1/0x1a0
       do_unlinkat+0x264/0x2b0
       do_fast_syscall_32+0x9a/0x2f0
       entry_SYSENTER_compat+0x84/0x96

-> #3 (sb_internal#2){.+.+}:
       lock_acquire+0xbd/0x220
       __sb_start_write+0x14d/0x230
       start_transaction+0x3e6/0x590
       btrfs_evict_inode+0x475/0x640
       evict+0xbf/0x1b0
       btrfs_run_delayed_iputs+0x6c/0x90
       cleaner_kthread+0x124/0x1a0
       kthread+0x106/0x140
       ret_from_fork+0x3a/0x50

-> #2 (&fs_info->cleaner_delayed_iput_mutex){+.+.}:
       lock_acquire+0xbd/0x220
       __mutex_lock+0x86/0xa10
       btrfs_alloc_data_chunk_ondemand+0x197/0x530
       btrfs_check_data_free_space+0x4c/0x90
       btrfs_delalloc_reserve_space+0x20/0x60
       btrfs_page_mkwrite+0x87/0x520
       do_page_mkwrite+0x31/0xa0
       __handle_mm_fault+0x799/0xb00
       handle_mm_fault+0x7c/0xe0
       __do_page_fault+0x1d3/0x4a0
       async_page_fault+0x1e/0x30

-> #1 (sb_pagefaults){.+.+}:
       lock_acquire+0xbd/0x220
       __sb_start_write+0x14d/0x230
       btrfs_page_mkwrite+0x6a/0x520
       do_page_mkwrite+0x31/0xa0
       __handle_mm_fault+0x799/0xb00
       handle_mm_fault+0x7c/0xe0
       __do_page_fault+0x1d3/0x4a0
       async_page_fault+0x1e/0x30

-> #0 (&mm->mmap_sem){++++}:
       __lock_acquire+0x42e/0x7a0
       lock_acquire+0xbd/0x220
       down_read+0x48/0xb0
       get_user_pages_unlocked+0x5a/0x1e0
       get_user_pages_fast+0xa4/0x150
       iov_iter_get_pages+0xc3/0x340
       do_direct_IO+0xf93/0x1d70
       __blockdev_direct_IO+0x32d/0x1c20
       btrfs_direct_IO+0x227/0x400
       generic_file_direct_write+0xcf/0x180
       btrfs_file_write_iter+0x308/0x58c
       aio_write+0xf8/0x1d0
       io_submit_one+0x3a9/0x620
       __ia32_compat_sys_io_submit+0xb2/0x270
       do_int80_syscall_32+0x5b/0x1a0
       entry_INT80_compat+0x88/0xa0

other info that might help us debug this:

Chain exists of:
  &mm->mmap_sem --> &ei->log_mutex --> &ei->dio_sem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ei->dio_sem);
                               lock(&ei->log_mutex);
                               lock(&ei->dio_sem);
  lock(&mm->mmap_sem);

 *** DEADLOCK ***

1 lock held by aio-dio-invalid/30928:
 #0: 00000000cefe6b35 (&ei->dio_sem){++++}, at: btrfs_direct_IO+0x3be/0x400

stack backtrace:
CPU: 0 PID: 30928 Comm: aio-dio-invalid Not tainted 4.18.0-rc4-xfstests-00025-g5de5edbaf1d4 #411
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014
Call Trace:
 dump_stack+0x7c/0xbb
 print_circular_bug.isra.37+0x297/0x2a4
 check_prev_add.constprop.45+0x781/0x7a0
 ? __lock_acquire+0x42e/0x7a0
 validate_chain.isra.41+0x7f0/0xb00
 __lock_acquire+0x42e/0x7a0
 lock_acquire+0xbd/0x220
 ? get_user_pages_unlocked+0x5a/0x1e0
 down_read+0x48/0xb0
 ? get_user_pages_unlocked+0x5a/0x1e0
 get_user_pages_unlocked+0x5a/0x1e0
 get_user_pages_fast+0xa4/0x150
 iov_iter_get_pages+0xc3/0x340
 do_direct_IO+0xf93/0x1d70
 ? __alloc_workqueue_key+0x358/0x490
 ? __blockdev_direct_IO+0x14b/0x1c20
 __blockdev_direct_IO+0x32d/0x1c20
 ? btrfs_run_delalloc_work+0x40/0x40
 ? can_nocow_extent+0x490/0x490
 ? kvm_clock_read+0x1f/0x30
 ? can_nocow_extent+0x490/0x490
 ? btrfs_run_delalloc_work+0x40/0x40
 btrfs_direct_IO+0x227/0x400
 ? btrfs_run_delalloc_work+0x40/0x40
 generic_file_direct_write+0xcf/0x180
 btrfs_file_write_iter+0x308/0x58c
 aio_write+0xf8/0x1d0
 ? kvm_clock_read+0x1f/0x30
 ? __might_fault+0x3e/0x90
 io_submit_one+0x3a9/0x620
 ? io_submit_one+0xe5/0x620
 __ia32_compat_sys_io_submit+0xb2/0x270
 do_int80_syscall_32+0x5b/0x1a0
 entry_INT80_compat+0x88/0xa0

CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Btrfs: fix assertion on fsync of regular file when using no-holes feature 2018-10-17T15:44:53+00:00 Filipe Manana fdmanana@suse.com 2018-10-15T08:51:00+00:00 7ed586d0a8241e81d58c656c5b315f781fa6fc97 When using the NO_HOLES feature and logging a regular file, we were expecting that if we find an inline extent, that either its size in RAM (uncompressed and unenconded) matches the size of the file or if it does not, that it matches the sector size and it represents compressed data. This assertion does not cover a case where the length of the inline extent is smaller than the sector size and also smaller the file's size, such case is possible through fallocate. Example: $ mkfs.btrfs -f -O no-holes /dev/sdb $ mount /dev/sdb /mnt $ xfs_io -f -c "pwrite -S 0xb60 0 21" /mnt/foobar $ xfs_io -c "falloc 40 40" /mnt/foobar $ xfs_io -c "fsync" /mnt/foobar In the above example we trigger the assertion because the inline extent's length is 21 bytes while the file size is 80 bytes. The fallocate() call merely updated the file's size and did not touch the existing inline extent, as expected. So fix this by adjusting the assertion so that an inline extent length smaller than the file size is valid if the file size is smaller than the filesystem's sector size. A test case for fstests follows soon. Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com> Fixes: a89ca6f24ffe ("Btrfs: fix fsync after truncate when no_holes feature is enabled") CC: stable@vger.kernel.org # 4.14+ Link: https://lore.kernel.org/linux-btrfs/CAE5jQCfRSBC7n4pUTFJcmHh109=gwyT9mFkCOL+NKfzswmR=_Q@mail.gmail.com/ Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> 
When using the NO_HOLES feature and logging a regular file, we were
expecting that if we find an inline extent, that either its size in RAM
(uncompressed and unenconded) matches the size of the file or if it does
not, that it matches the sector size and it represents compressed data.
This assertion does not cover a case where the length of the inline extent
is smaller than the sector size and also smaller the file's size, such
case is possible through fallocate. Example:

  $ mkfs.btrfs -f -O no-holes /dev/sdb
  $ mount /dev/sdb /mnt

  $ xfs_io -f -c "pwrite -S 0xb60 0 21" /mnt/foobar
  $ xfs_io -c "falloc 40 40" /mnt/foobar
  $ xfs_io -c "fsync" /mnt/foobar

In the above example we trigger the assertion because the inline extent's
length is 21 bytes while the file size is 80 bytes. The fallocate() call
merely updated the file's size and did not touch the existing inline
extent, as expected.

So fix this by adjusting the assertion so that an inline extent length
smaller than the file size is valid if the file size is smaller than the
filesystem's sector size.

A test case for fstests follows soon.

Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Fixes: a89ca6f24ffe ("Btrfs: fix fsync after truncate when no_holes feature is enabled")
CC: stable@vger.kernel.org # 4.14+
Link: https://lore.kernel.org/linux-btrfs/CAE5jQCfRSBC7n4pUTFJcmHh109=gwyT9mFkCOL+NKfzswmR=_Q@mail.gmail.com/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Btrfs: fix wrong dentries after fsync of file that got its parent replaced 2018-10-15T15:23:39+00:00 Filipe Manana fdmanana@suse.com 2018-10-09T14:05:29+00:00 0f375eed92b5a407657532637ed9652611a682f5 In a scenario like the following: mkdir /mnt/A # inode 258 mkdir /mnt/B # inode 259 touch /mnt/B/bar # inode 260 sync mv /mnt/B/bar /mnt/A/bar mv -T /mnt/A /mnt/B fsync /mnt/B/bar <power fail> After replaying the log we end up with file bar having 2 hard links, both with the name 'bar' and one in the directory with inode number 258 and the other in the directory with inode number 259. Also, we end up with the directory inode 259 still existing and with the directory inode 258 still named as 'A', instead of 'B'. In this scenario, file 'bar' should only have one hard link, located at directory inode 258, the directory inode 259 should not exist anymore and the name for directory inode 258 should be 'B'. This incorrect behaviour happens because when attempting to log the old parents of an inode, we skip any parents that no longer exist. Fix this by forcing a full commit if an old parent no longer exists. A test case for fstests follows soon. CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> 
In a scenario like the following:

  mkdir /mnt/A               # inode 258
  mkdir /mnt/B               # inode 259
  touch /mnt/B/bar           # inode 260

  sync

  mv /mnt/B/bar /mnt/A/bar
  mv -T /mnt/A /mnt/B
  fsync /mnt/B/bar

  <power fail>

After replaying the log we end up with file bar having 2 hard links, both
with the name 'bar' and one in the directory with inode number 258 and the
other in the directory with inode number 259. Also, we end up with the
directory inode 259 still existing and with the directory inode 258 still
named as 'A', instead of 'B'. In this scenario, file 'bar' should only
have one hard link, located at directory inode 258, the directory inode
259 should not exist anymore and the name for directory inode 258 should
be 'B'.

This incorrect behaviour happens because when attempting to log the old
parents of an inode, we skip any parents that no longer exist. Fix this
by forcing a full commit if an old parent no longer exists.

A test case for fstests follows soon.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Btrfs: fix warning when replaying log after fsync of a tmpfile 2018-10-15T15:23:39+00:00 Filipe Manana fdmanana@suse.com 2018-10-08T10:12:55+00:00 f2d72f42d5fa3bf33761d9e47201745f624fcff5 When replaying a log which contains a tmpfile (which necessarily has a link count of 0) we end up calling inc_nlink(), at fs/btrfs/tree-log.c:replay_one_buffer(), which produces a warning like the following: [195191.943673] WARNING: CPU: 0 PID: 6924 at fs/inode.c:342 inc_nlink+0x33/0x40 [195191.943723] CPU: 0 PID: 6924 Comm: mount Not tainted 4.19.0-rc6-btrfs-next-38 #1 [195191.943724] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org 04/01/2014 [195191.943726] RIP: 0010:inc_nlink+0x33/0x40 [195191.943728] RSP: 0018:ffffb96e425e3870 EFLAGS: 00010246 [195191.943730] RAX: 0000000000000000 RBX: ffff8c0d1e6af4f0 RCX: 0000000000000006 [195191.943731] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8c0d1e6af4f0 [195191.943731] RBP: 0000000000000097 R08: 0000000000000001 R09: 0000000000000000 [195191.943732] R10: 0000000000000000 R11: 0000000000000000 R12: ffffb96e425e3a60 [195191.943733] R13: ffff8c0d10cff0c8 R14: ffff8c0d0d515348 R15: ffff8c0d78a1b3f8 [195191.943735] FS: 00007f570ee24480(0000) GS:ffff8c0dfb200000(0000) knlGS:0000000000000000 [195191.943736] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [195191.943737] CR2: 00005593286277c8 CR3: 00000000bb8f2006 CR4: 00000000003606f0 [195191.943739] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [195191.943740] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [195191.943741] Call Trace: [195191.943778] replay_one_buffer+0x797/0x7d0 [btrfs] [195191.943802] walk_up_log_tree+0x1c1/0x250 [btrfs] [195191.943809] ? rcu_read_lock_sched_held+0x3f/0x70 [195191.943825] walk_log_tree+0xae/0x1d0 [btrfs] [195191.943840] btrfs_recover_log_trees+0x1d7/0x4d0 [btrfs] [195191.943856] ? replay_dir_deletes+0x280/0x280 [btrfs] [195191.943870] open_ctree+0x1c3b/0x22a0 [btrfs] [195191.943887] btrfs_mount_root+0x6b4/0x800 [btrfs] [195191.943894] ? rcu_read_lock_sched_held+0x3f/0x70 [195191.943899] ? pcpu_alloc+0x55b/0x7c0 [195191.943906] ? mount_fs+0x3b/0x140 [195191.943908] mount_fs+0x3b/0x140 [195191.943912] ? __init_waitqueue_head+0x36/0x50 [195191.943916] vfs_kern_mount+0x62/0x160 [195191.943927] btrfs_mount+0x134/0x890 [btrfs] [195191.943936] ? rcu_read_lock_sched_held+0x3f/0x70 [195191.943938] ? pcpu_alloc+0x55b/0x7c0 [195191.943943] ? mount_fs+0x3b/0x140 [195191.943952] ? btrfs_remount+0x570/0x570 [btrfs] [195191.943954] mount_fs+0x3b/0x140 [195191.943956] ? __init_waitqueue_head+0x36/0x50 [195191.943960] vfs_kern_mount+0x62/0x160 [195191.943963] do_mount+0x1f9/0xd40 [195191.943967] ? memdup_user+0x4b/0x70 [195191.943971] ksys_mount+0x7e/0xd0 [195191.943974] __x64_sys_mount+0x21/0x30 [195191.943977] do_syscall_64+0x60/0x1b0 [195191.943980] entry_SYSCALL_64_after_hwframe+0x49/0xbe [195191.943983] RIP: 0033:0x7f570e4e524a [195191.943986] RSP: 002b:00007ffd83589478 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5 [195191.943989] RAX: ffffffffffffffda RBX: 0000563f335b2060 RCX: 00007f570e4e524a [195191.943990] RDX: 0000563f335b2240 RSI: 0000563f335b2280 RDI: 0000563f335b2260 [195191.943992] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000020 [195191.943993] R10: 00000000c0ed0000 R11: 0000000000000206 R12: 0000563f335b2260 [195191.943994] R13: 0000563f335b2240 R14: 0000000000000000 R15: 00000000ffffffff [195191.944002] irq event stamp: 8688 [195191.944010] hardirqs last enabled at (8687): [<ffffffff9cb004c3>] console_unlock+0x503/0x640 [195191.944012] hardirqs last disabled at (8688): [<ffffffff9ca037dd>] trace_hardirqs_off_thunk+0x1a/0x1c [195191.944018] softirqs last enabled at (8638): [<ffffffff9cc0a5d1>] __set_page_dirty_nobuffers+0x101/0x150 [195191.944020] softirqs last disabled at (8634): [<ffffffff9cc26bbe>] wb_wakeup_delayed+0x2e/0x60 [195191.944022] ---[ end trace 5d6e873a9a0b811a ]--- This happens because the inode does not have the flag I_LINKABLE set, which is a runtime only flag, not meant to be persisted, set when the inode is created through open(2) if the flag O_EXCL is not passed to it. Except for the warning, there are no other consequences (like corruptions or metadata inconsistencies). Since it's pointless to replay a tmpfile as it would be deleted in a later phase of the log replay procedure (it has a link count of 0), fix this by not logging tmpfiles and if a tmpfile is found in a log (created by a kernel without this change), skip the replay of the inode. A test case for fstests follows soon. Fixes: 471d557afed1 ("Btrfs: fix loss of prealloc extents past i_size after fsync log replay") CC: stable@vger.kernel.org # 4.18+ Reported-by: Martin Steigerwald <martin@lichtvoll.de> Link: https://lore.kernel.org/linux-btrfs/3666619.NTnn27ZJZE@merkaba/ Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> 
When replaying a log which contains a tmpfile (which necessarily has a
link count of 0) we end up calling inc_nlink(), at
fs/btrfs/tree-log.c:replay_one_buffer(), which produces a warning like
the following:

  [195191.943673] WARNING: CPU: 0 PID: 6924 at fs/inode.c:342 inc_nlink+0x33/0x40
  [195191.943723] CPU: 0 PID: 6924 Comm: mount Not tainted 4.19.0-rc6-btrfs-next-38 #1
  [195191.943724] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org 04/01/2014
  [195191.943726] RIP: 0010:inc_nlink+0x33/0x40
  [195191.943728] RSP: 0018:ffffb96e425e3870 EFLAGS: 00010246
  [195191.943730] RAX: 0000000000000000 RBX: ffff8c0d1e6af4f0 RCX: 0000000000000006
  [195191.943731] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8c0d1e6af4f0
  [195191.943731] RBP: 0000000000000097 R08: 0000000000000001 R09: 0000000000000000
  [195191.943732] R10: 0000000000000000 R11: 0000000000000000 R12: ffffb96e425e3a60
  [195191.943733] R13: ffff8c0d10cff0c8 R14: ffff8c0d0d515348 R15: ffff8c0d78a1b3f8
  [195191.943735] FS:  00007f570ee24480(0000) GS:ffff8c0dfb200000(0000) knlGS:0000000000000000
  [195191.943736] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [195191.943737] CR2: 00005593286277c8 CR3: 00000000bb8f2006 CR4: 00000000003606f0
  [195191.943739] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  [195191.943740] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  [195191.943741] Call Trace:
  [195191.943778]  replay_one_buffer+0x797/0x7d0 [btrfs]
  [195191.943802]  walk_up_log_tree+0x1c1/0x250 [btrfs]
  [195191.943809]  ? rcu_read_lock_sched_held+0x3f/0x70
  [195191.943825]  walk_log_tree+0xae/0x1d0 [btrfs]
  [195191.943840]  btrfs_recover_log_trees+0x1d7/0x4d0 [btrfs]
  [195191.943856]  ? replay_dir_deletes+0x280/0x280 [btrfs]
  [195191.943870]  open_ctree+0x1c3b/0x22a0 [btrfs]
  [195191.943887]  btrfs_mount_root+0x6b4/0x800 [btrfs]
  [195191.943894]  ? rcu_read_lock_sched_held+0x3f/0x70
  [195191.943899]  ? pcpu_alloc+0x55b/0x7c0
  [195191.943906]  ? mount_fs+0x3b/0x140
  [195191.943908]  mount_fs+0x3b/0x140
  [195191.943912]  ? __init_waitqueue_head+0x36/0x50
  [195191.943916]  vfs_kern_mount+0x62/0x160
  [195191.943927]  btrfs_mount+0x134/0x890 [btrfs]
  [195191.943936]  ? rcu_read_lock_sched_held+0x3f/0x70
  [195191.943938]  ? pcpu_alloc+0x55b/0x7c0
  [195191.943943]  ? mount_fs+0x3b/0x140
  [195191.943952]  ? btrfs_remount+0x570/0x570 [btrfs]
  [195191.943954]  mount_fs+0x3b/0x140
  [195191.943956]  ? __init_waitqueue_head+0x36/0x50
  [195191.943960]  vfs_kern_mount+0x62/0x160
  [195191.943963]  do_mount+0x1f9/0xd40
  [195191.943967]  ? memdup_user+0x4b/0x70
  [195191.943971]  ksys_mount+0x7e/0xd0
  [195191.943974]  __x64_sys_mount+0x21/0x30
  [195191.943977]  do_syscall_64+0x60/0x1b0
  [195191.943980]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [195191.943983] RIP: 0033:0x7f570e4e524a
  [195191.943986] RSP: 002b:00007ffd83589478 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
  [195191.943989] RAX: ffffffffffffffda RBX: 0000563f335b2060 RCX: 00007f570e4e524a
  [195191.943990] RDX: 0000563f335b2240 RSI: 0000563f335b2280 RDI: 0000563f335b2260
  [195191.943992] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000020
  [195191.943993] R10: 00000000c0ed0000 R11: 0000000000000206 R12: 0000563f335b2260
  [195191.943994] R13: 0000563f335b2240 R14: 0000000000000000 R15: 00000000ffffffff
  [195191.944002] irq event stamp: 8688
  [195191.944010] hardirqs last  enabled at (8687): [<ffffffff9cb004c3>] console_unlock+0x503/0x640
  [195191.944012] hardirqs last disabled at (8688): [<ffffffff9ca037dd>] trace_hardirqs_off_thunk+0x1a/0x1c
  [195191.944018] softirqs last  enabled at (8638): [<ffffffff9cc0a5d1>] __set_page_dirty_nobuffers+0x101/0x150
  [195191.944020] softirqs last disabled at (8634): [<ffffffff9cc26bbe>] wb_wakeup_delayed+0x2e/0x60
  [195191.944022] ---[ end trace 5d6e873a9a0b811a ]---

This happens because the inode does not have the flag I_LINKABLE set,
which is a runtime only flag, not meant to be persisted, set when the
inode is created through open(2) if the flag O_EXCL is not passed to it.
Except for the warning, there are no other consequences (like corruptions
or metadata inconsistencies).

Since it's pointless to replay a tmpfile as it would be deleted in a
later phase of the log replay procedure (it has a link count of 0), fix
this by not logging tmpfiles and if a tmpfile is found in a log (created
by a kernel without this change), skip the replay of the inode.

A test case for fstests follows soon.

Fixes: 471d557afed1 ("Btrfs: fix loss of prealloc extents past i_size after fsync log replay")
CC: stable@vger.kernel.org # 4.18+
Reported-by: Martin Steigerwald <martin@lichtvoll.de>
Link: https://lore.kernel.org/linux-btrfs/3666619.NTnn27ZJZE@merkaba/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: fix error handling in free_log_tree 2018-10-15T15:23:29+00:00 Jeff Mahoney jeffm@suse.com 2018-09-06T20:59:33+00:00 374b0e2d6ba5da7fd1cadb3247731ff27d011f6f When we hit an I/O error in free_log_tree->walk_log_tree during file system shutdown we can crash due to there not being a valid transaction handle. Use btrfs_handle_fs_error when there's no transaction handle to use. BUG: unable to handle kernel NULL pointer dereference at 0000000000000060 IP: free_log_tree+0xd2/0x140 [btrfs] PGD 0 P4D 0 Oops: 0000 [#1] SMP DEBUG_PAGEALLOC PTI Modules linked in: <modules> CPU: 2 PID: 23544 Comm: umount Tainted: G W 4.12.14-kvmsmall #9 SLE15 (unreleased) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014 task: ffff96bfd3478880 task.stack: ffffa7cf40d78000 RIP: 0010:free_log_tree+0xd2/0x140 [btrfs] RSP: 0018:ffffa7cf40d7bd10 EFLAGS: 00010282 RAX: 00000000fffffffb RBX: 00000000fffffffb RCX: 0000000000000002 RDX: 0000000000000000 RSI: ffff96c02f07d4c8 RDI: 0000000000000282 RBP: ffff96c013cf1000 R08: ffff96c02f07d4c8 R09: ffff96c02f07d4d0 R10: 0000000000000000 R11: 0000000000000002 R12: 0000000000000000 R13: ffff96c005e800c0 R14: ffffa7cf40d7bdb8 R15: 0000000000000000 FS: 00007f17856bcfc0(0000) GS:ffff96c03f600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000060 CR3: 0000000045ed6002 CR4: 00000000003606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ? wait_for_writer+0xb0/0xb0 [btrfs] btrfs_free_log+0x17/0x30 [btrfs] btrfs_drop_and_free_fs_root+0x9a/0xe0 [btrfs] btrfs_free_fs_roots+0xc0/0x130 [btrfs] ? wait_for_completion+0xf2/0x100 close_ctree+0xea/0x2e0 [btrfs] ? kthread_stop+0x161/0x260 generic_shutdown_super+0x6c/0x120 kill_anon_super+0xe/0x20 btrfs_kill_super+0x13/0x100 [btrfs] deactivate_locked_super+0x3f/0x70 cleanup_mnt+0x3b/0x70 task_work_run+0x78/0x90 exit_to_usermode_loop+0x77/0xa6 do_syscall_64+0x1c5/0x1e0 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x7f1784f90827 RSP: 002b:00007ffdeeb03118 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000556a60c62970 RCX: 00007f1784f90827 RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000556a60c62b50 RBP: 0000000000000000 R08: 0000000000000005 R09: 00000000ffffffff R10: 0000556a60c63900 R11: 0000000000000246 R12: 0000556a60c62b50 R13: 00007f17854a81c4 R14: 0000000000000000 R15: 0000000000000000 RIP: free_log_tree+0xd2/0x140 [btrfs] RSP: ffffa7cf40d7bd10 CR2: 0000000000000060 Fixes: 681ae50917df9 ("Btrfs: cleanup reserved space when freeing tree log on error") CC: <stable@vger.kernel.org> # v3.13 Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> 
When we hit an I/O error in free_log_tree->walk_log_tree during file system
shutdown we can crash due to there not being a valid transaction handle.

Use btrfs_handle_fs_error when there's no transaction handle to use.

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000060
  IP: free_log_tree+0xd2/0x140 [btrfs]
  PGD 0 P4D 0
  Oops: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
  Modules linked in: <modules>
  CPU: 2 PID: 23544 Comm: umount Tainted: G        W        4.12.14-kvmsmall #9 SLE15 (unreleased)
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
  task: ffff96bfd3478880 task.stack: ffffa7cf40d78000
  RIP: 0010:free_log_tree+0xd2/0x140 [btrfs]
  RSP: 0018:ffffa7cf40d7bd10 EFLAGS: 00010282
  RAX: 00000000fffffffb RBX: 00000000fffffffb RCX: 0000000000000002
  RDX: 0000000000000000 RSI: ffff96c02f07d4c8 RDI: 0000000000000282
  RBP: ffff96c013cf1000 R08: ffff96c02f07d4c8 R09: ffff96c02f07d4d0
  R10: 0000000000000000 R11: 0000000000000002 R12: 0000000000000000
  R13: ffff96c005e800c0 R14: ffffa7cf40d7bdb8 R15: 0000000000000000
  FS:  00007f17856bcfc0(0000) GS:ffff96c03f600000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000060 CR3: 0000000045ed6002 CR4: 00000000003606e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   ? wait_for_writer+0xb0/0xb0 [btrfs]
   btrfs_free_log+0x17/0x30 [btrfs]
   btrfs_drop_and_free_fs_root+0x9a/0xe0 [btrfs]
   btrfs_free_fs_roots+0xc0/0x130 [btrfs]
   ? wait_for_completion+0xf2/0x100
   close_ctree+0xea/0x2e0 [btrfs]
   ? kthread_stop+0x161/0x260
   generic_shutdown_super+0x6c/0x120
   kill_anon_super+0xe/0x20
   btrfs_kill_super+0x13/0x100 [btrfs]
   deactivate_locked_super+0x3f/0x70
   cleanup_mnt+0x3b/0x70
   task_work_run+0x78/0x90
   exit_to_usermode_loop+0x77/0xa6
   do_syscall_64+0x1c5/0x1e0
   entry_SYSCALL_64_after_hwframe+0x42/0xb7
  RIP: 0033:0x7f1784f90827
  RSP: 002b:00007ffdeeb03118 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
  RAX: 0000000000000000 RBX: 0000556a60c62970 RCX: 00007f1784f90827
  RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000556a60c62b50
  RBP: 0000000000000000 R08: 0000000000000005 R09: 00000000ffffffff
  R10: 0000556a60c63900 R11: 0000000000000246 R12: 0000556a60c62b50
  R13: 00007f17854a81c4 R14: 0000000000000000 R15: 0000000000000000
  RIP: free_log_tree+0xd2/0x140 [btrfs] RSP: ffffa7cf40d7bd10
  CR2: 0000000000000060

Fixes: 681ae50917df9 ("Btrfs: cleanup reserved space when freeing tree log on error")
CC: <stable@vger.kernel.org> # v3.13
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>