@@ -834,8 +834,15 @@ typedef struct xfs_attr_leaf_name_remote {
typedef struct xfs_attr_leafblock {
xfs_attr_leaf_hdr_t hdr; /* constant-structure header block */
xfs_attr_leaf_entry_t entries[1]; /* sorted on key, not name */
- xfs_attr_leaf_name_local_t namelist; /* grows from bottom of buf */
- xfs_attr_leaf_name_remote_t valuelist; /* grows from bottom of buf */
+ /*
+ * The rest of the block contains the following structures after the
+ * leaf entries, growing from the bottom up. The variables are never
+ * referenced and definining them can actually make gcc optimize away
+ * accesses to the 'entries' array above index 0 so don't do that.
+ *
+ * xfs_attr_leaf_name_local_t namelist;
+ * xfs_attr_leaf_name_remote_t valuelist;
+ */
} xfs_attr_leafblock_t;
/*
This is a note to let you know that I have just added a patch titled xfs: Fix xfs_attr_leafblock definition to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt28. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From bce97fea023aef80e3a661d17d4cff53a720dd6f Mon Sep 17 00:00:00 2001 From: Jan Kara <jack@suse.com> Date: Wed, 19 Aug 2015 10:34:32 +1000 Subject: xfs: Fix xfs_attr_leafblock definition commit ffeecc5213024ae663377b442eedcfbacf6d0c5d upstream. struct xfs_attr_leafblock contains 'entries' array which is declared with size 1 altough it can in fact contain much more entries. Since this array is followed by further struct members, gcc (at least in version 4.8.3) thinks that the array has the fixed size of 1 element and thus may optimize away all accesses beyond the end of array resulting in non-working code. This problem was only observed with userspace code in xfsprogs, however it's better to be safe in kernel as well and have matching kernel and xfsprogs definitions. Signed-off-by: Jan Kara <jack@suse.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com> [ luis: backported to 3.16: - file rename: fs/xfs/libxfs/xfs_da_format.h -> fs/xfs/xfs_da_format.h ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- fs/xfs/xfs_da_format.h | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) -- 1.9.1