Commit b2f49033 authored Feb 17, 2006 by Peter Staubach Committed by Linus Torvalds Feb 17, 2006

[PATCH] fix deadlock in ext2



Fix a deadlock possible in the ext2 file system implementation.  This
deadlock occurs when a file is removed from an ext2 file system which was
mounted with the "sync" mount option.

The problem is that ext2_xattr_delete_inode() was invoking the routine,
sync_dirty_buffer(), using a buffer head which was previously locked via
lock_buffer().  The first thing that sync_dirty_buffer() does is to lock
the buffer head that it was passed.  It does this via lock_buffer().  Oops.

The solution is to unlock the buffer head in ext2_xattr_delete_inode()
before invoking sync_dirty_buffer().  This makes the code in
ext2_xattr_delete_inode() obey the same locking rules as all other callers
of sync_dirty_buffer() in the ext2 file system implementation.

Signed-off-by: Peter Staubach <staubach@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 614f8f50

fs/ext2/xattr.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -792,18 +792,20 @@ ext2_xattr_delete_inode(struct inode *inode)
		ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
		get_bh(bh);
		bforget(bh);
		unlock_buffer(bh);
		} else {
		HDR(bh)->h_refcount = cpu_to_le32(
		le32_to_cpu(HDR(bh)->h_refcount) - 1);
		if (ce)
		mb_cache_entry_release(ce);
		ea_bdebug(bh, "refcount now=%d",
		le32_to_cpu(HDR(bh)->h_refcount));
		unlock_buffer(bh);
		mark_buffer_dirty(bh);
		if (IS_SYNC(inode))
		sync_dirty_buffer(bh);
		DQUOT_FREE_BLOCK(inode, 1);
		}
		ea_bdebug(bh, "refcount now=%d", le32_to_cpu(HDR(bh)->h_refcount) - 1);
		unlock_buffer(bh);
		EXT2_I(inode)->i_file_acl = 0;

		cleanup:

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