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| 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) | |
| download | linux-c1bb05a657fb3d8c6179a4ef7980261fae4521d7.tar.gz linux-c1bb05a657fb3d8c6179a4ef7980261fae4521d7.tar.bz2 linux-c1bb05a657fb3d8c6179a4ef7980261fae4521d7.zip | |
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, ext4_free_blocks(handle, inode, bh, 0, 1, EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET); + unlock_buffer(bh); } else { le32_add_cpu(&BHDR(bh)->h_refcount, -1); + if (ce) + mb_cache_entry_release(ce); + unlock_buffer(bh); error = ext4_handle_dirty_metadata(handle, inode, bh); if (IS_SYNC(inode)) ext4_handle_sync(handle); dquot_free_block(inode, 1); ea_bdebug(bh, "refcount now=%d; releasing", le32_to_cpu(BHDR(bh)->h_refcount)); - if (ce) - mb_cache_entry_release(ce); } - unlock_buffer(bh); out: ext4_std_error(inode->i_sb, error); return; |