Messages in this thread Patch in this message | | | Date | Wed, 15 Feb 2006 10:31:53 -0500 | From | Peter Staubach <> | Subject | [PATCH] deadlock in ext2 |
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Hi.
The attached patch addresses 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.
Thanx...
ps
Signed-off-by: Peter Staubach <staubach@redhat.com> --- linux-2.6.15.x86_64/fs/ext2/xattr.c.org +++ linux-2.6.15.x86_64/fs/ext2/xattr.c @@ -792,18 +792,20 @@ ext2_xattr_delete_inode(struct inode *in 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: | |