diff options
author | Eric Sandeen <sandeen@redhat.com> | 2012-02-20 23:06:18 -0500 |
---|---|---|
committer | Theodore Ts'o <tytso@mit.edu> | 2012-02-20 23:06:18 -0500 |
commit | c1bb05a657fb3d8c6179a4ef7980261fae4521d7 (patch) | |
tree | 57345a9505bd8e2713381adc864d4ed935b0f6c8 /fs/ext4 | |
parent | a0ade1deb86d2325aecc36272bb4505a6eec9235 (diff) |
ext4: avoid deadlock on sync-mounted FS w/o journal
Processes hang forever on a sync-mounted ext2 file system that
is mounted with the ext4 module (default in Fedora 16).
I can reproduce this reliably by mounting an ext2 partition with
"-o sync" and opening a new file an that partition with vim. vim
will hang in "D" state forever. The same happens on ext4 without
a journal.
I am attaching a small patch here that solves this issue for me.
In the sync mounted case without a journal,
ext4_handle_dirty_metadata() may call sync_dirty_buffer(), which
can't be called with buffer lock held.
Also move mb_cache_entry_release inside lock to avoid race
fixed previously by 8a2bfdcb ext[34]: EA block reference count racing fix
Note too that ext2 fixed this same problem in 2006 with
b2f49033 [PATCH] fix deadlock in ext2
Signed-off-by: Martin.Wilck@ts.fujitsu.com
[sandeen@redhat.com: move mb_cache_entry_release before unlock, edit commit msg]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
-rw-r--r-- | fs/ext4/xattr.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 1bff752d1b59..3369157df852 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c | |||
@@ -484,18 +484,19 @@ ext4_xattr_release_block(handle_t *handle, struct inode *inode, | |||
484 | ext4_free_blocks(handle, inode, bh, 0, 1, | 484 | ext4_free_blocks(handle, inode, bh, 0, 1, |
485 | EXT4_FREE_BLOCKS_METADATA | | 485 | EXT4_FREE_BLOCKS_METADATA | |
486 | EXT4_FREE_BLOCKS_FORGET); | 486 | EXT4_FREE_BLOCKS_FORGET); |
487 | unlock_buffer(bh); | ||
487 | } else { | 488 | } else { |
488 | le32_add_cpu(&BHDR(bh)->h_refcount, -1); | 489 | le32_add_cpu(&BHDR(bh)->h_refcount, -1); |
490 | if (ce) | ||
491 | mb_cache_entry_release(ce); | ||
492 | unlock_buffer(bh); | ||
489 | error = ext4_handle_dirty_metadata(handle, inode, bh); | 493 | error = ext4_handle_dirty_metadata(handle, inode, bh); |
490 | if (IS_SYNC(inode)) | 494 | if (IS_SYNC(inode)) |
491 | ext4_handle_sync(handle); | 495 | ext4_handle_sync(handle); |
492 | dquot_free_block(inode, 1); | 496 | dquot_free_block(inode, 1); |
493 | ea_bdebug(bh, "refcount now=%d; releasing", | 497 | ea_bdebug(bh, "refcount now=%d; releasing", |
494 | le32_to_cpu(BHDR(bh)->h_refcount)); | 498 | le32_to_cpu(BHDR(bh)->h_refcount)); |
495 | if (ce) | ||
496 | mb_cache_entry_release(ce); | ||
497 | } | 499 | } |
498 | unlock_buffer(bh); | ||
499 | out: | 500 | out: |
500 | ext4_std_error(inode->i_sb, error); | 501 | ext4_std_error(inode->i_sb, error); |
501 | return; | 502 | return; |