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authorEric Sandeen <sandeen@redhat.com>2012-02-20 23:06:18 -0500
committerTheodore Ts'o <tytso@mit.edu>2012-02-20 23:06:18 -0500
commitc1bb05a657fb3d8c6179a4ef7980261fae4521d7 (patch)
tree57345a9505bd8e2713381adc864d4ed935b0f6c8 /fs/ext4
parenta0ade1deb86d2325aecc36272bb4505a6eec9235 (diff)
downloadop-kernel-dev-c1bb05a657fb3d8c6179a4ef7980261fae4521d7.zip
op-kernel-dev-c1bb05a657fb3d8c6179a4ef7980261fae4521d7.tar.gz
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.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 1bff752..3369157 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;
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