From: Eric Sandeen Date: Tue, 10 Mar 2009 22:18:47 +0000 (-0400) Subject: ext4: fix header check in ext4_ext_search_right() for deep extent trees. X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=395a87bfefbc400011417e9eaae33169f9f036c0;p=openwrt%2Fstaging%2Fblogic.git ext4: fix header check in ext4_ext_search_right() for deep extent trees. The ext4_ext_search_right() function is confusing; it uses a "depth" variable which is 0 at the root and maximum at the leaves, but the on-disk metadata uses a "depth" (actually eh_depth) which is opposite: maximum at the root, and 0 at the leaves. The ext4_ext_check_header() function is given a depth and checks the header agaisnt that depth; it expects the on-disk semantics, but we are giving it the opposite in the while loop in this function. We should be giving it the on-disk notion of "depth" which we can get from (p_depth - depth) - and if you look, the last (more commonly hit) call to ext4_ext_check_header() does just this. Sending in the wrong depth results in (incorrect) messages about corruption: EXT4-fs error (device sdb1): ext4_ext_search_right: bad header in inode #2621457: unexpected eh_depth - magic f30a, entries 340, max 340(0), depth 1(2) http://bugzilla.kernel.org/show_bug.cgi?id=12821 Reported-by: David Dindorp Signed-off-by: Eric Sandeen Signed-off-by: "Theodore Ts'o" --- diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index e2eab196875f..e0aa4fe4f596 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -1122,7 +1122,8 @@ ext4_ext_search_right(struct inode *inode, struct ext4_ext_path *path, struct ext4_extent_idx *ix; struct ext4_extent *ex; ext4_fsblk_t block; - int depth, ee_len; + int depth; /* Note, NOT eh_depth; depth from top of tree */ + int ee_len; BUG_ON(path == NULL); depth = path->p_depth; @@ -1179,7 +1180,8 @@ got_index: if (bh == NULL) return -EIO; eh = ext_block_hdr(bh); - if (ext4_ext_check_header(inode, eh, depth)) { + /* subtract from p_depth to get proper eh_depth */ + if (ext4_ext_check_header(inode, eh, path->p_depth - depth)) { put_bh(bh); return -EIO; }