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| author | Josef Bacik <jbacik@fb.com> | 2018-07-20 11:46:10 -0700 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2018-08-06 13:12:58 +0200 |
| commit | 3c4276936f6fbe52884b4ea4e6cc120b890a0f9f (patch) | |
| tree | 5efe9f1d1fc3ce8ac71b742ef466790996110473 /fs/btrfs | |
| parent | 97aff912a2fa75555641303d42bd4c723a98df5d (diff) | |
| download | linux-3c4276936f6fbe52884b4ea4e6cc120b890a0f9f.tar.bz2 | |
Btrfs: fix btrfs_write_inode vs delayed iput deadlock
We recently ran into the following deadlock involving
btrfs_write_inode():
[ +0.005066] __schedule+0x38e/0x8c0
[ +0.007144] schedule+0x36/0x80
[ +0.006447] bit_wait+0x11/0x60
[ +0.006446] __wait_on_bit+0xbe/0x110
[ +0.007487] ? bit_wait_io+0x60/0x60
[ +0.007319] __inode_wait_for_writeback+0x96/0xc0
[ +0.009568] ? autoremove_wake_function+0x40/0x40
[ +0.009565] inode_wait_for_writeback+0x21/0x30
[ +0.009224] evict+0xb0/0x190
[ +0.006099] iput+0x1a8/0x210
[ +0.006103] btrfs_run_delayed_iputs+0x73/0xc0
[ +0.009047] btrfs_commit_transaction+0x799/0x8c0
[ +0.009567] btrfs_write_inode+0x81/0xb0
[ +0.008008] __writeback_single_inode+0x267/0x320
[ +0.009569] writeback_sb_inodes+0x25b/0x4e0
[ +0.008702] wb_writeback+0x102/0x2d0
[ +0.007487] wb_workfn+0xa4/0x310
[ +0.006794] ? wb_workfn+0xa4/0x310
[ +0.007143] process_one_work+0x150/0x410
[ +0.008179] worker_thread+0x6d/0x520
[ +0.007490] kthread+0x12c/0x160
[ +0.006620] ? put_pwq_unlocked+0x80/0x80
[ +0.008185] ? kthread_park+0xa0/0xa0
[ +0.007484] ? do_syscall_64+0x53/0x150
[ +0.007837] ret_from_fork+0x29/0x40
Writeback calls:
btrfs_write_inode
btrfs_commit_transaction
btrfs_run_delayed_iputs
If iput() is called on that same inode, evict() will wait for writeback
forever.
btrfs_write_inode() was originally added way back in 4730a4bc5bf3
("btrfs_dirty_inode") to support O_SYNC writes. However, ->write_inode()
hasn't been used for O_SYNC since 148f948ba877 ("vfs: Introduce new
helpers for syncing after writing to O_SYNC file or IS_SYNC inode"), so
btrfs_write_inode() is actually unnecessary (and leads to a bunch of
unnecessary commits). Get rid of it, which also gets rid of the
deadlock.
CC: stable@vger.kernel.org # 3.2+
Signed-off-by: Josef Bacik <jbacik@fb.com>
[Omar: new commit message]
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/inode.c | 26 | ||||
| -rw-r--r-- | fs/btrfs/super.c | 1 |
2 files changed, 0 insertions, 27 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 4955e04da4c8..472457795486 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -6021,32 +6021,6 @@ err: return ret; } -int btrfs_write_inode(struct inode *inode, struct writeback_control *wbc) -{ - struct btrfs_root *root = BTRFS_I(inode)->root; - struct btrfs_trans_handle *trans; - int ret = 0; - bool nolock = false; - - if (test_bit(BTRFS_INODE_DUMMY, &BTRFS_I(inode)->runtime_flags)) - return 0; - - if (btrfs_fs_closing(root->fs_info) && - btrfs_is_free_space_inode(BTRFS_I(inode))) - nolock = true; - - if (wbc->sync_mode == WB_SYNC_ALL) { - if (nolock) - trans = btrfs_join_transaction_nolock(root); - else - trans = btrfs_join_transaction(root); - if (IS_ERR(trans)) - return PTR_ERR(trans); - ret = btrfs_commit_transaction(trans); - } - return ret; -} - /* * This is somewhat expensive, updating the tree every time the * inode changes. But, it is most likely to find the inode in cache. diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index efe8b03ce380..67de3c0fc85b 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -2344,7 +2344,6 @@ static const struct super_operations btrfs_super_ops = { .sync_fs = btrfs_sync_fs, .show_options = btrfs_show_options, .show_devname = btrfs_show_devname, - .write_inode = btrfs_write_inode, .alloc_inode = btrfs_alloc_inode, .destroy_inode = btrfs_destroy_inode, .statfs = btrfs_statfs, |