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Commit b2f49033 authored by Peter Staubach's avatar Peter Staubach Committed by Linus Torvalds
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[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: default avatarPeter Staubach <staubach@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus 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: