10 files changed, 198 insertions, 59 deletions

diff --git a/Documentation/filesystems/xfs.txt b/Documentation/filesystems/xfs.txt
index 3e4b3dd1e046..83577f0232a0 100644
--- a/Documentation/filesystems/xfs.txt
+++ b/Documentation/filesystems/xfs.txt
@@ -33,6 +33,9 @@ When mounting an XFS filesystem, the following options are accepted.
         removing extended attributes) the on-disk superblock feature
         bit field will be updated to reflect this format being in use.
 
+        CRC enabled filesystems always use the attr2 format, and so
+        will reject the noattr2 mount option if it is set.
+
   barrier
         Enables the use of block layer write barriers for writes into
         the journal and unwritten extent conversion.  This allows for
diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c
index 1d32f1d52763..306d883d89bc 100644
--- a/fs/xfs/xfs_acl.c
+++ b/fs/xfs/xfs_acl.c
@@ -21,6 +21,8 @@
 #include "xfs_bmap_btree.h"
 #include "xfs_inode.h"
 #include "xfs_vnodeops.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
 #include "xfs_trace.h"
 #include <linux/slab.h>
 #include <linux/xattr.h>
@@ -34,7 +36,9 @@
  */
 
 STATIC struct posix_acl *
-xfs_acl_from_disk(struct xfs_acl *aclp)
+xfs_acl_from_disk(
+        struct xfs_acl  *aclp,
+        int             max_entries)
 {
         struct posix_acl_entry *acl_e;
         struct posix_acl *acl;
@@ -42,7 +46,7 @@ xfs_acl_from_disk(struct xfs_acl *aclp)
         unsigned int count, i;
 
         count = be32_to_cpu(aclp->acl_cnt);
-        if (count > XFS_ACL_MAX_ENTRIES)
+        if (count > max_entries)
                 return ERR_PTR(-EFSCORRUPTED);
 
         acl = posix_acl_alloc(count, GFP_KERNEL);
@@ -108,9 +112,9 @@ xfs_get_acl(struct inode *inode, int type)
         struct xfs_inode *ip = XFS_I(inode);
         struct posix_acl *acl;
         struct xfs_acl *xfs_acl;
-        int len = sizeof(struct xfs_acl);
         unsigned char *ea_name;
         int error;
+        int len;
 
         acl = get_cached_acl(inode, type);
         if (acl != ACL_NOT_CACHED)
@@ -133,8 +137,8 @@ xfs_get_acl(struct inode *inode, int type)
          * If we have a cached ACLs value just return it, not need to
          * go out to the disk.
          */
-
-        xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
+        len = XFS_ACL_MAX_SIZE(ip->i_mount);
+        xfs_acl = kzalloc(len, GFP_KERNEL);
         if (!xfs_acl)
                 return ERR_PTR(-ENOMEM);
 
@@ -153,7 +157,7 @@ xfs_get_acl(struct inode *inode, int type)
                 goto out;
         }
 
-        acl = xfs_acl_from_disk(xfs_acl);
+        acl = xfs_acl_from_disk(xfs_acl, XFS_ACL_MAX_ENTRIES(ip->i_mount));
         if (IS_ERR(acl))
                 goto out;
 
@@ -189,16 +193,17 @@ xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 
         if (acl) {
                 struct xfs_acl *xfs_acl;
-                int len;
+                int len = XFS_ACL_MAX_SIZE(ip->i_mount);
 
-                xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
+                xfs_acl = kzalloc(len, GFP_KERNEL);
                 if (!xfs_acl)
                         return -ENOMEM;
 
                 xfs_acl_to_disk(xfs_acl, acl);
-                len = sizeof(struct xfs_acl) -
-                        (sizeof(struct xfs_acl_entry) *
-                         (XFS_ACL_MAX_ENTRIES - acl->a_count));
+
+                /* subtract away the unused acl entries */
+                len -= sizeof(struct xfs_acl_entry) *
+                         (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
 
                 error = -xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
                                 len, ATTR_ROOT);
@@ -243,7 +248,7 @@ xfs_set_mode(struct inode *inode, umode_t mode)
 static int
 xfs_acl_exists(struct inode *inode, unsigned char *name)
 {
-        int len = sizeof(struct xfs_acl);
+        int len = XFS_ACL_MAX_SIZE(XFS_M(inode->i_sb));
 
         return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
                             ATTR_ROOT|ATTR_KERNOVAL) == 0);
@@ -379,7 +384,7 @@ xfs_xattr_acl_set(struct dentry *dentry, const char *name,
                 goto out_release;
 
         error = -EINVAL;
-        if (acl->a_count > XFS_ACL_MAX_ENTRIES)
+        if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
                 goto out_release;
 
         if (type == ACL_TYPE_ACCESS) {
diff --git a/fs/xfs/xfs_acl.h b/fs/xfs/xfs_acl.h
index 39632d941354..4016a567b83c 100644
--- a/fs/xfs/xfs_acl.h
+++ b/fs/xfs/xfs_acl.h
@@ -22,19 +22,36 @@ struct inode;
 struct posix_acl;
 struct xfs_inode;
 
-#define XFS_ACL_MAX_ENTRIES 25
 #define XFS_ACL_NOT_PRESENT (-1)
 
 /* On-disk XFS access control list structure */
+struct xfs_acl_entry {
+        __be32  ae_tag;
+        __be32  ae_id;
+        __be16  ae_perm;
+        __be16  ae_pad;         /* fill the implicit hole in the structure */
+};
+
 struct xfs_acl {
-        __be32          acl_cnt;
-        struct xfs_acl_entry {
-                __be32  ae_tag;
-                __be32  ae_id;
-                __be16  ae_perm;
-        } acl_entry[XFS_ACL_MAX_ENTRIES];
+        __be32                  acl_cnt;
+        struct xfs_acl_entry    acl_entry[0];
 };
 
+/*
+ * The number of ACL entries allowed is defined by the on-disk format.
+ * For v4 superblocks, that is limited to 25 entries. For v5 superblocks, it is
+ * limited only by the maximum size of the xattr that stores the information.
+ */
+#define XFS_ACL_MAX_ENTRIES(mp) \
+        (xfs_sb_version_hascrc(&mp->m_sb) \
+                ?  (XATTR_SIZE_MAX - sizeof(struct xfs_acl)) / \
+                                                sizeof(struct xfs_acl_entry) \
+                : 25)
+
+#define XFS_ACL_MAX_SIZE(mp) \
+        (sizeof(struct xfs_acl) + \
+                sizeof(struct xfs_acl_entry) * XFS_ACL_MAX_ENTRIES((mp)))
+
 /* On-disk XFS extended attribute names */
 #define SGI_ACL_FILE            (unsigned char *)"SGI_ACL_FILE"
 #define SGI_ACL_DEFAULT         (unsigned char *)"SGI_ACL_DEFAULT"
diff --git a/fs/xfs/xfs_attr_leaf.c b/fs/xfs/xfs_attr_leaf.c
index d788302e506a..31d3cd129269 100644
--- a/fs/xfs/xfs_attr_leaf.c
+++ b/fs/xfs/xfs_attr_leaf.c
@@ -3258,7 +3258,7 @@ xfs_attr3_leaf_inactive(
                         name_rmt = xfs_attr3_leaf_name_remote(leaf, i);
                         if (name_rmt->valueblk) {
                                 lp->valueblk = be32_to_cpu(name_rmt->valueblk);
-                                lp->valuelen = XFS_B_TO_FSB(dp->i_mount,
+                                lp->valuelen = xfs_attr3_rmt_blocks(dp->i_mount,
                                                     be32_to_cpu(name_rmt->valuelen));
                                 lp++;
                         }
diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index a41f8bf1da37..044e97a33c8d 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -249,8 +249,11 @@ xfs_qm_init_dquot_blk(
                 d->dd_diskdq.d_version = XFS_DQUOT_VERSION;
                 d->dd_diskdq.d_id = cpu_to_be32(curid);
                 d->dd_diskdq.d_flags = type;
-                if (xfs_sb_version_hascrc(&mp->m_sb))
+                if (xfs_sb_version_hascrc(&mp->m_sb)) {
                         uuid_copy(&d->dd_uuid, &mp->m_sb.sb_uuid);
+                        xfs_update_cksum((char *)d, sizeof(struct xfs_dqblk),
+                                         XFS_DQUOT_CRC_OFF);
+                }
         }
 
         xfs_trans_dquot_buf(tp, bp,
@@ -286,23 +289,6 @@ xfs_dquot_set_prealloc_limits(struct xfs_dquot *dqp)
         dqp->q_low_space[XFS_QLOWSP_5_PCNT] = space * 5;
 }
 
-STATIC void
-xfs_dquot_buf_calc_crc(
-        struct xfs_mount        *mp,
-        struct xfs_buf          *bp)
-{
-        struct xfs_dqblk        *d = (struct xfs_dqblk *)bp->b_addr;
-        int                     i;
-
-        if (!xfs_sb_version_hascrc(&mp->m_sb))
-                return;
-
-        for (i = 0; i < mp->m_quotainfo->qi_dqperchunk; i++, d++) {
-                xfs_update_cksum((char *)d, sizeof(struct xfs_dqblk),
-                                 offsetof(struct xfs_dqblk, dd_crc));
-        }
-}
-
 STATIC bool
 xfs_dquot_buf_verify_crc(
         struct xfs_mount        *mp,
@@ -328,12 +314,11 @@ xfs_dquot_buf_verify_crc(
 
         for (i = 0; i < ndquots; i++, d++) {
                 if (!xfs_verify_cksum((char *)d, sizeof(struct xfs_dqblk),
-                                 offsetof(struct xfs_dqblk, dd_crc)))
+                                 XFS_DQUOT_CRC_OFF))
                         return false;
                 if (!uuid_equal(&d->dd_uuid, &mp->m_sb.sb_uuid))
                         return false;
         }
-
         return true;
 }
 
@@ -393,6 +378,11 @@ xfs_dquot_buf_read_verify(
         }
 }
 
+/*
+ * we don't calculate the CRC here as that is done when the dquot is flushed to
+ * the buffer after the update is done. This ensures that the dquot in the
+ * buffer always has an up-to-date CRC value.
+ */
 void
 xfs_dquot_buf_write_verify(
         struct xfs_buf  *bp)
@@ -404,7 +394,6 @@ xfs_dquot_buf_write_verify(
                 xfs_buf_ioerror(bp, EFSCORRUPTED);
                 return;
         }
-        xfs_dquot_buf_calc_crc(mp, bp);
 }
 
 const struct xfs_buf_ops xfs_dquot_buf_ops = {
@@ -1151,11 +1140,17 @@ xfs_qm_dqflush(
          * copy the lsn into the on-disk dquot now while we have the in memory
          * dquot here. This can't be done later in the write verifier as we
          * can't get access to the log item at that point in time.
+         *
+         * We also calculate the CRC here so that the on-disk dquot in the
+         * buffer always has a valid CRC. This ensures there is no possibility
+         * of a dquot without an up-to-date CRC getting to disk.
          */
         if (xfs_sb_version_hascrc(&mp->m_sb)) {
                 struct xfs_dqblk *dqb = (struct xfs_dqblk *)ddqp;
 
                 dqb->dd_lsn = cpu_to_be64(dqp->q_logitem.qli_item.li_lsn);
+                xfs_update_cksum((char *)dqb, sizeof(struct xfs_dqblk),
+                                 XFS_DQUOT_CRC_OFF);
         }
 
         /*
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index efbe1accb6ca..7f7be5f98f52 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1638,6 +1638,10 @@ xfs_iunlink(
                 dip->di_next_unlinked = agi->agi_unlinked[bucket_index];
                 offset = ip->i_imap.im_boffset +
                         offsetof(xfs_dinode_t, di_next_unlinked);
+
+                /* need to recalc the inode CRC if appropriate */
+                xfs_dinode_calc_crc(mp, dip);
+
                 xfs_trans_inode_buf(tp, ibp);
                 xfs_trans_log_buf(tp, ibp, offset,
                                   (offset + sizeof(xfs_agino_t) - 1));
@@ -1723,6 +1727,10 @@ xfs_iunlink_remove(
                         dip->di_next_unlinked = cpu_to_be32(NULLAGINO);
                         offset = ip->i_imap.im_boffset +
                                 offsetof(xfs_dinode_t, di_next_unlinked);
+
+                        /* need to recalc the inode CRC if appropriate */
+                        xfs_dinode_calc_crc(mp, dip);
+
                         xfs_trans_inode_buf(tp, ibp);
                         xfs_trans_log_buf(tp, ibp, offset,
                                           (offset + sizeof(xfs_agino_t) - 1));
@@ -1796,6 +1804,10 @@ xfs_iunlink_remove(
                         dip->di_next_unlinked = cpu_to_be32(NULLAGINO);
                         offset = ip->i_imap.im_boffset +
                                 offsetof(xfs_dinode_t, di_next_unlinked);
+
+                        /* need to recalc the inode CRC if appropriate */
+                        xfs_dinode_calc_crc(mp, dip);
+
                         xfs_trans_inode_buf(tp, ibp);
                         xfs_trans_log_buf(tp, ibp, offset,
                                           (offset + sizeof(xfs_agino_t) - 1));
@@ -1809,6 +1821,10 @@ xfs_iunlink_remove(
                 last_dip->di_next_unlinked = cpu_to_be32(next_agino);
                 ASSERT(next_agino != 0);
                 offset = last_offset + offsetof(xfs_dinode_t, di_next_unlinked);
+
+                /* need to recalc the inode CRC if appropriate */
+                xfs_dinode_calc_crc(mp, last_dip);
+
                 xfs_trans_inode_buf(tp, last_ibp);
                 xfs_trans_log_buf(tp, last_ibp, offset,
                                   (offset + sizeof(xfs_agino_t) - 1));
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index d9e4d3c3991a..45a85ff84da1 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -1599,10 +1599,43 @@ xlog_recover_add_to_trans(
 }
 
 /*
- * Sort the log items in the transaction. Cancelled buffers need
- * to be put first so they are processed before any items that might
- * modify the buffers. If they are cancelled, then the modifications
- * don't need to be replayed.
+ * Sort the log items in the transaction.
+ *
+ * The ordering constraints are defined by the inode allocation and unlink
+ * behaviour. The rules are:
+ *
+ *      1. Every item is only logged once in a given transaction. Hence it
+ *         represents the last logged state of the item. Hence ordering is
+ *         dependent on the order in which operations need to be performed so
+ *         required initial conditions are always met.
+ *
+ *      2. Cancelled buffers are recorded in pass 1 in a separate table and
+ *         there's nothing to replay from them so we can simply cull them
+ *         from the transaction. However, we can't do that until after we've
+ *         replayed all the other items because they may be dependent on the
+ *         cancelled buffer and replaying the cancelled buffer can remove it
+ *         form the cancelled buffer table. Hence they have tobe done last.
+ *
+ *      3. Inode allocation buffers must be replayed before inode items that
+ *         read the buffer and replay changes into it.
+ *
+ *      4. Inode unlink buffers must be replayed after inode items are replayed.
+ *         This ensures that inodes are completely flushed to the inode buffer
+ *         in a "free" state before we remove the unlinked inode list pointer.
+ *
+ * Hence the ordering needs to be inode allocation buffers first, inode items
+ * second, inode unlink buffers third and cancelled buffers last.
+ *
+ * But there's a problem with that - we can't tell an inode allocation buffer
+ * apart from a regular buffer, so we can't separate them. We can, however,
+ * tell an inode unlink buffer from the others, and so we can separate them out
+ * from all the other buffers and move them to last.
+ *
+ * Hence, 4 lists, in order from head to tail:
+ *      - buffer_list for all buffers except cancelled/inode unlink buffers
+ *      - item_list for all non-buffer items
+ *      - inode_buffer_list for inode unlink buffers
+ *      - cancel_list for the cancelled buffers
  */
 STATIC int
 xlog_recover_reorder_trans(
@@ -1612,6 +1645,10 @@ xlog_recover_reorder_trans(
 {
         xlog_recover_item_t     *item, *n;
         LIST_HEAD(sort_list);
+        LIST_HEAD(cancel_list);
+        LIST_HEAD(buffer_list);
+        LIST_HEAD(inode_buffer_list);
+        LIST_HEAD(inode_list);
 
         list_splice_init(&trans->r_itemq, &sort_list);
         list_for_each_entry_safe(item, n, &sort_list, ri_list) {
@@ -1619,12 +1656,18 @@ xlog_recover_reorder_trans(
 
                 switch (ITEM_TYPE(item)) {
                 case XFS_LI_BUF:
-                        if (!(buf_f->blf_flags & XFS_BLF_CANCEL)) {
+                        if (buf_f->blf_flags & XFS_BLF_CANCEL) {
                                 trace_xfs_log_recover_item_reorder_head(log,
                                                         trans, item, pass);
-                                list_move(&item->ri_list, &trans->r_itemq);
+                                list_move(&item->ri_list, &cancel_list);
+                                break;
+                        }
+                        if (buf_f->blf_flags & XFS_BLF_INODE_BUF) {
+                                list_move(&item->ri_list, &inode_buffer_list);
                                 break;
                         }
+                        list_move_tail(&item->ri_list, &buffer_list);
+                        break;
                 case XFS_LI_INODE:
                 case XFS_LI_DQUOT:
                 case XFS_LI_QUOTAOFF:
@@ -1632,7 +1675,7 @@ xlog_recover_reorder_trans(
                 case XFS_LI_EFI:
                         trace_xfs_log_recover_item_reorder_tail(log,
                                                         trans, item, pass);
-                        list_move_tail(&item->ri_list, &trans->r_itemq);
+                        list_move_tail(&item->ri_list, &inode_list);
                         break;
                 default:
                         xfs_warn(log->l_mp,
@@ -1643,6 +1686,14 @@ xlog_recover_reorder_trans(
                 }
         }
         ASSERT(list_empty(&sort_list));
+        if (!list_empty(&buffer_list))
+                list_splice(&buffer_list, &trans->r_itemq);
+        if (!list_empty(&inode_list))
+                list_splice_tail(&inode_list, &trans->r_itemq);
+        if (!list_empty(&inode_buffer_list))
+                list_splice_tail(&inode_buffer_list, &trans->r_itemq);
+        if (!list_empty(&cancel_list))
+                list_splice_tail(&cancel_list, &trans->r_itemq);
         return 0;
 }
 
@@ -1861,6 +1912,15 @@ xlog_recover_do_inode_buffer(
                 buffer_nextp = (xfs_agino_t *)xfs_buf_offset(bp,
                                               next_unlinked_offset);
                 *buffer_nextp = *logged_nextp;
+
+                /*
+                 * If necessary, recalculate the CRC in the on-disk inode. We
+                 * have to leave the inode in a consistent state for whoever
+                 * reads it next....
+                 */
+                xfs_dinode_calc_crc(mp, (struct xfs_dinode *)
+                                xfs_buf_offset(bp, i * mp->m_sb.sb_inodesize));
+
         }
 
         return 0;
@@ -2266,6 +2326,12 @@ xfs_qm_dqcheck(
         d->dd_diskdq.d_flags = type;
         d->dd_diskdq.d_id = cpu_to_be32(id);
 
+        if (xfs_sb_version_hascrc(&mp->m_sb)) {
+                uuid_copy(&d->dd_uuid, &mp->m_sb.sb_uuid);
+                xfs_update_cksum((char *)d, sizeof(struct xfs_dqblk),
+                                 XFS_DQUOT_CRC_OFF);
+        }
+
         return errs;
 }
 
@@ -2793,6 +2859,10 @@ xlog_recover_dquot_pass2(
         }
 
         memcpy(ddq, recddq, item->ri_buf[1].i_len);
+        if (xfs_sb_version_hascrc(&mp->m_sb)) {
+                xfs_update_cksum((char *)ddq, sizeof(struct xfs_dqblk),
+                                 XFS_DQUOT_CRC_OFF);
+        }
 
         ASSERT(dq_f->qlf_size == 2);
         ASSERT(bp->b_target->bt_mount == mp);
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index f41702b43003..b75c9bb6e71e 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -41,6 +41,7 @@
 #include "xfs_qm.h"
 #include "xfs_trace.h"
 #include "xfs_icache.h"
+#include "xfs_cksum.h"
 
 /*
  * The global quota manager. There is only one of these for the entire
@@ -839,7 +840,7 @@ xfs_qm_reset_dqcounts(
         xfs_dqid_t      id,
         uint            type)
 {
-        xfs_disk_dquot_t        *ddq;
+        struct xfs_dqblk        *dqb;
         int                     j;
 
         trace_xfs_reset_dqcounts(bp, _RET_IP_);
@@ -853,8 +854,12 @@ xfs_qm_reset_dqcounts(
         do_div(j, sizeof(xfs_dqblk_t));
         ASSERT(mp->m_quotainfo->qi_dqperchunk == j);
 #endif
-        ddq = bp->b_addr;
+        dqb = bp->b_addr;
         for (j = 0; j < mp->m_quotainfo->qi_dqperchunk; j++) {
+                struct xfs_disk_dquot   *ddq;
+
+                ddq = (struct xfs_disk_dquot *)&dqb[j];
+
                 /*
                  * Do a sanity check, and if needed, repair the dqblk. Don't
                  * output any warnings because it's perfectly possible to
@@ -871,7 +876,12 @@ xfs_qm_reset_dqcounts(
                 ddq->d_bwarns = 0;
                 ddq->d_iwarns = 0;
                 ddq->d_rtbwarns = 0;
-                ddq = (xfs_disk_dquot_t *) ((xfs_dqblk_t *)ddq + 1);
+
+                if (xfs_sb_version_hascrc(&mp->m_sb)) {
+                        xfs_update_cksum((char *)&dqb[j],
+                                         sizeof(struct xfs_dqblk),
+                                         XFS_DQUOT_CRC_OFF);
+                }
         }
 }
 
@@ -907,19 +917,29 @@ xfs_qm_dqiter_bufs(
                               XFS_FSB_TO_DADDR(mp, bno),
                               mp->m_quotainfo->qi_dqchunklen, 0, &bp,
                               &xfs_dquot_buf_ops);
-                if (error)
-                        break;
 
                 /*
-                 * XXX(hch): need to figure out if it makes sense to validate
-                 *           the CRC here.
+                 * CRC and validation errors will return a EFSCORRUPTED here. If
+                 * this occurs, re-read without CRC validation so that we can
+                 * repair the damage via xfs_qm_reset_dqcounts(). This process
+                 * will leave a trace in the log indicating corruption has
+                 * been detected.
                  */
+                if (error == EFSCORRUPTED) {
+                        error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp,
+                                      XFS_FSB_TO_DADDR(mp, bno),
+                                      mp->m_quotainfo->qi_dqchunklen, 0, &bp,
+                                      NULL);
+                }
+
+                if (error)
+                        break;
+
                 xfs_qm_reset_dqcounts(mp, bp, firstid, type);
                 xfs_buf_delwri_queue(bp, buffer_list);
                 xfs_buf_relse(bp);
-                /*
-                 * goto the next block.
-                 */
+
+                /* goto the next block. */
                 bno++;
                 firstid += mp->m_quotainfo->qi_dqperchunk;
         }
diff --git a/fs/xfs/xfs_quota.h b/fs/xfs/xfs_quota.h
index c61e31c7d997..c38068f26c55 100644
--- a/fs/xfs/xfs_quota.h
+++ b/fs/xfs/xfs_quota.h
@@ -87,6 +87,8 @@ typedef struct xfs_dqblk {
         uuid_t            dd_uuid;      /* location information */
 } xfs_dqblk_t;
 
+#define XFS_DQUOT_CRC_OFF       offsetof(struct xfs_dqblk, dd_crc)
+
 /*
  * flags for q_flags field in the dquot.
  */
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index ea341cea68cb..3033ba5e9762 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1373,6 +1373,17 @@ xfs_finish_flags(
         }
 
         /*
+         * V5 filesystems always use attr2 format for attributes.
+         */
+        if (xfs_sb_version_hascrc(&mp->m_sb) &&
+            (mp->m_flags & XFS_MOUNT_NOATTR2)) {
+                xfs_warn(mp,
+"Cannot mount a V5 filesystem as %s. %s is always enabled for V5 filesystems.",
+                        MNTOPT_NOATTR2, MNTOPT_ATTR2);
+                return XFS_ERROR(EINVAL);
+        }
+
+        /*
          * mkfs'ed attr2 will turn on attr2 mount unless explicitly
          * told by noattr2 to turn it off
          */