xfs: fix endian conversion issue in discard code

commit b1c770c273a4787069306fc82aab245e9ac72e9d upstream

When finding the longest extent in an AG, we read the value directly
out of the AGF buffer without endian conversion. This will give an
incorrect length, resulting in FITRIM operations potentially not
trimming everything that it should.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/xfs/xfs_discard.c b/fs/xfs/xfs_discard.c
index 8a24f0c6c86053e8dfd96a2bdd793f3d8e950659..286a051f12cfd779f553f209452cd2539d042de6 100644 (file)
--- a/fs/xfs/xfs_discard.c
+++ b/fs/xfs/xfs_discard.c
@@ -68,7 +68,7 @@ xfs_trim_extents(
         * Look up the longest btree in the AGF and start with it.
         */
        error = xfs_alloc_lookup_le(cur, 0,
-                                   XFS_BUF_TO_AGF(agbp)->agf_longest, &i);
+                           be32_to_cpu(XFS_BUF_TO_AGF(agbp)->agf_longest), &i);
        if (error)
                goto out_del_cursor;
 
@@ -84,7 +84,7 @@ xfs_trim_extents(
                if (error)
                        goto out_del_cursor;
                XFS_WANT_CORRUPTED_GOTO(i == 1, out_del_cursor);
-               ASSERT(flen <= XFS_BUF_TO_AGF(agbp)->agf_longest);
+               ASSERT(flen <= be32_to_cpu(XFS_BUF_TO_AGF(agbp)->agf_longest));
 
                /*
                 * Too small?  Give up.