xfs: add CRC checks for quota blocks

Use the reserved space in struct xfs_dqblk to store a UUID and a crc
for the quota blocks.

[dchinner@redhat.com] Add a LSN field and update for current verifier
infrastructure.

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

5 files changed, 141 insertions, 17 deletions

diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index 45bb08f6ba17..a41f8bf1da37 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -36,6 +36,7 @@
 #include "xfs_trans_space.h"
 #include "xfs_trans_priv.h"
 #include "xfs_qm.h"
+#include "xfs_cksum.h"
 #include "xfs_trace.h"
 
 /*
@@ -248,6 +249,8 @@ 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))
+                        uuid_copy(&d->dd_uuid, &mp->m_sb.sb_uuid);
         }
 
         xfs_trans_dquot_buf(tp, bp,
@@ -283,25 +286,87 @@ xfs_dquot_set_prealloc_limits(struct xfs_dquot *dqp)
         dqp->q_low_space[XFS_QLOWSP_5_PCNT] = space * 5;
 }
 
-static void
+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,
+        struct xfs_buf          *bp)
+{
+        struct xfs_dqblk        *d = (struct xfs_dqblk *)bp->b_addr;
+        int                     ndquots;
+        int                     i;
+
+        if (!xfs_sb_version_hascrc(&mp->m_sb))
+                return true;
+
+        /*
+         * if we are in log recovery, the quota subsystem has not been
+         * initialised so we have no quotainfo structure. In that case, we need
+         * to manually calculate the number of dquots in the buffer.
+         */
+        if (mp->m_quotainfo)
+                ndquots = mp->m_quotainfo->qi_dqperchunk;
+        else
+                ndquots = xfs_qm_calc_dquots_per_chunk(mp,
+                                        XFS_BB_TO_FSB(mp, bp->b_length));
+
+        for (i = 0; i < ndquots; i++, d++) {
+                if (!xfs_verify_cksum((char *)d, sizeof(struct xfs_dqblk),
+                                 offsetof(struct xfs_dqblk, dd_crc)))
+                        return false;
+                if (!uuid_equal(&d->dd_uuid, &mp->m_sb.sb_uuid))
+                        return false;
+        }
+
+        return true;
+}
+
+STATIC bool
 xfs_dquot_buf_verify(
+        struct xfs_mount        *mp,
         struct xfs_buf          *bp)
 {
-        struct xfs_mount        *mp = bp->b_target->bt_mount;
         struct xfs_dqblk        *d = (struct xfs_dqblk *)bp->b_addr;
-        struct xfs_disk_dquot   *ddq;
         xfs_dqid_t              id = 0;
+        int                     ndquots;
         int                     i;
 
         /*
+         * if we are in log recovery, the quota subsystem has not been
+         * initialised so we have no quotainfo structure. In that case, we need
+         * to manually calculate the number of dquots in the buffer.
+         */
+        if (mp->m_quotainfo)
+                ndquots = mp->m_quotainfo->qi_dqperchunk;
+        else
+                ndquots = xfs_qm_calc_dquots_per_chunk(mp, bp->b_length);
+
+        /*
          * On the first read of the buffer, verify that each dquot is valid.
          * We don't know what the id of the dquot is supposed to be, just that
          * they should be increasing monotonically within the buffer. If the
          * first id is corrupt, then it will fail on the second dquot in the
          * buffer so corruptions could point to the wrong dquot in this case.
          */
-        for (i = 0; i < mp->m_quotainfo->qi_dqperchunk; i++) {
-                int     error;
+        for (i = 0; i < ndquots; i++) {
+                struct xfs_disk_dquot   *ddq;
+                int                     error;
 
                 ddq = &d[i].dd_diskdq;
 
@@ -309,27 +374,37 @@ xfs_dquot_buf_verify(
                         id = be32_to_cpu(ddq->d_id);
 
                 error = xfs_qm_dqcheck(mp, ddq, id + i, 0, XFS_QMOPT_DOWARN,
-                                        "xfs_dquot_read_verify");
-                if (error) {
-                        XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, d);
-                        xfs_buf_ioerror(bp, EFSCORRUPTED);
-                        break;
-                }
+                                       "xfs_dquot_buf_verify");
+                if (error)
+                        return false;
         }
+        return true;
 }
 
 static void
 xfs_dquot_buf_read_verify(
         struct xfs_buf  *bp)
 {
-        xfs_dquot_buf_verify(bp);
+        struct xfs_mount        *mp = bp->b_target->bt_mount;
+
+        if (!xfs_dquot_buf_verify_crc(mp, bp) || !xfs_dquot_buf_verify(mp, bp)) {
+                XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
+                xfs_buf_ioerror(bp, EFSCORRUPTED);
+        }
 }
 
 void
 xfs_dquot_buf_write_verify(
         struct xfs_buf  *bp)
 {
-        xfs_dquot_buf_verify(bp);
+        struct xfs_mount        *mp = bp->b_target->bt_mount;
+
+        if (!xfs_dquot_buf_verify(mp, bp)) {
+                XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
+                xfs_buf_ioerror(bp, EFSCORRUPTED);
+                return;
+        }
+        xfs_dquot_buf_calc_crc(mp, bp);
 }
 
 const struct xfs_buf_ops xfs_dquot_buf_ops = {
@@ -1073,6 +1148,17 @@ xfs_qm_dqflush(
                                         &dqp->q_logitem.qli_item.li_lsn);
 
         /*
+         * 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.
+         */
+        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);
+        }
+
+        /*
          * Attach an iodone routine so that we can remove this dquot from the
          * AIL and release the flush lock once the dquot is synced to disk.
          */
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 6778a7943db4..27b3ec214a67 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -1979,6 +1979,16 @@ xlog_recover_do_reg_buffer(
                 }
                 bp->b_ops = &xfs_agi_buf_ops;
                 break;
+        case XFS_BLF_UDQUOT_BUF:
+        case XFS_BLF_PDQUOT_BUF:
+        case XFS_BLF_GDQUOT_BUF:
+                if (*(__be16 *)bp->b_addr != cpu_to_be16(XFS_DQUOT_MAGIC)) {
+                        xfs_warn(mp, "Bad DQUOT block magic!");
+                        ASSERT(0);
+                        break;
+                }
+                bp->b_ops = &xfs_dquot_buf_ops;
+                break;
         default:
                 break;
         }
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index d0acb4e40a6f..f41702b43003 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -617,6 +617,20 @@ xfs_qm_dqdetach(
         }
 }
 
+int
+xfs_qm_calc_dquots_per_chunk(
+        struct xfs_mount        *mp,
+        unsigned int            nbblks) /* basic block units */
+{
+        unsigned int    ndquots;
+
+        ASSERT(nbblks > 0);
+        ndquots = BBTOB(nbblks);
+        do_div(ndquots, sizeof(xfs_dqblk_t));
+
+        return ndquots;
+}
+
 /*
  * This initializes all the quota information that's kept in the
  * mount structure
@@ -656,9 +670,8 @@ xfs_qm_init_quotainfo(
 
         /* Precalc some constants */
         qinf->qi_dqchunklen = XFS_FSB_TO_BB(mp, XFS_DQUOT_CLUSTER_SIZE_FSB);
-        ASSERT(qinf->qi_dqchunklen);
-        qinf->qi_dqperchunk = BBTOB(qinf->qi_dqchunklen);
-        do_div(qinf->qi_dqperchunk, sizeof(xfs_dqblk_t));
+        qinf->qi_dqperchunk = xfs_qm_calc_dquots_per_chunk(mp,
+                                                        qinf->qi_dqchunklen);
 
         mp->m_qflags |= (mp->m_sb.sb_qflags & XFS_ALL_QUOTA_CHKD);
 
@@ -897,6 +910,10 @@ xfs_qm_dqiter_bufs(
                 if (error)
                         break;
 
+                /*
+                 * XXX(hch): need to figure out if it makes sense to validate
+                 *           the CRC here.
+                 */
                 xfs_qm_reset_dqcounts(mp, bp, firstid, type);
                 xfs_buf_delwri_queue(bp, buffer_list);
                 xfs_buf_relse(bp);
diff --git a/fs/xfs/xfs_qm.h b/fs/xfs/xfs_qm.h
index 82c21084587b..5d16a6e6900f 100644
--- a/fs/xfs/xfs_qm.h
+++ b/fs/xfs/xfs_qm.h
@@ -75,6 +75,8 @@ typedef struct xfs_quotainfo {
          &((qi)->qi_gquota_tree))
 
 
+extern int      xfs_qm_calc_dquots_per_chunk(struct xfs_mount *mp,
+                                             unsigned int nbblks);
 extern void     xfs_trans_mod_dquot(xfs_trans_t *, xfs_dquot_t *, uint, long);
 extern int      xfs_trans_reserve_quota_bydquots(xfs_trans_t *, xfs_mount_t *,
                         xfs_dquot_t *, xfs_dquot_t *, long, long, uint);
diff --git a/fs/xfs/xfs_quota.h b/fs/xfs/xfs_quota.h
index b50ec5b95d5a..c61e31c7d997 100644
--- a/fs/xfs/xfs_quota.h
+++ b/fs/xfs/xfs_quota.h
@@ -77,7 +77,14 @@ typedef struct	xfs_disk_dquot {
  */
 typedef struct xfs_dqblk {
         xfs_disk_dquot_t  dd_diskdq;    /* portion that lives incore as well */
-        char              dd_fill[32];  /* filling for posterity */
+        char              dd_fill[4];   /* filling for posterity */
+
+        /*
+         * These two are only present on filesystems with the CRC bits set.
+         */
+        __be32            dd_crc;       /* checksum */
+        __be64            dd_lsn;       /* last modification in log */
+        uuid_t            dd_uuid;      /* location information */
 } xfs_dqblk_t;
 
 /*
@@ -380,5 +387,7 @@ extern int xfs_qm_dqcheck(struct xfs_mount *, xfs_disk_dquot_t *,
                                 xfs_dqid_t, uint, uint, char *);
 extern int xfs_mount_reset_sbqflags(struct xfs_mount *);
 
+extern const struct xfs_buf_ops xfs_dquot_buf_ops;
+
 #endif  /* __KERNEL__ */
 #endif  /* __XFS_QUOTA_H__ */