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[PATCH v2] repair: update extent count after zapping duplicate blocks

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: [PATCH v2] repair: update extent count after zapping duplicate blocks
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Thu, 2 Feb 2012 07:39:10 -0500
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20111213021207.GY14273@dastard>
References: <20111202174619.179530033@xxxxxxxxxxxxxxxxxxxxxx> <20111202174741.904845954@xxxxxxxxxxxxxxxxxxxxxx> <20111213021207.GY14273@dastard>
User-agent: Mutt/1.5.21 (2010-09-15)
When we find a duplicate extent in an extern format inode we do not zap
the whole inode, but just truncate it to the point where the duplicate
extent was found.  But the current code only updates di_nblocks for the
new size, but no di_nextents/di_anextents.  In most cases this isn't noticed,
but when moving such an inode to the lost+found directoy the consistency
check in xfs_iformat trips over it.  Fix this by updating the on-disk
extent count as part of the inode repair.

Note that we zap btree format inodes with duplicate block completely
at this point, so this fix doesn't apply to them.

Reported-by: Arkadiusz Mi??kiewicz <arekm@xxxxxxxx>
Tested-by: Arkadiusz Mi??kiewicz <arekm@xxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>

---
updates since v2:
  - address review comments from Dave

Index: xfsprogs-dev/repair/dinode.c
===================================================================
--- xfsprogs-dev.orig/repair/dinode.c   2012-01-11 11:23:30.000000000 +0000
+++ xfsprogs-dev/repair/dinode.c        2012-02-02 11:19:43.000000000 +0000
@@ -606,7 +606,7 @@ int
 process_bmbt_reclist_int(
        xfs_mount_t             *mp,
        xfs_bmbt_rec_t          *rp,
-       int                     numrecs,
+       int                     *numrecs,
        int                     type,
        xfs_ino_t               ino,
        xfs_drfsbno_t           *tot,
@@ -642,7 +642,7 @@ process_bmbt_reclist_int(
        else
                ftype = _("regular");
 
-       for (i = 0; i < numrecs; i++) {
+       for (i = 0; i < *numrecs; i++) {
                libxfs_bmbt_disk_get_all(rp + i, &irec);
                if (i == 0)
                        *last_key = *first_key = irec.br_startoff;
@@ -831,6 +831,13 @@ _("illegal state %d in block map %" PRIu
 done:
        if (locked_agno != -1)
                pthread_mutex_unlock(&ag_locks[locked_agno]);
+
+       if (i != *numrecs) {
+               ASSERT(i < *numrecs);
+               do_warn(_("correcting nextents for inode %" PRIu64 "\n"), ino);
+               *numrecs = i;
+       }
+
        return error;
 }
 
@@ -842,7 +849,7 @@ int
 process_bmbt_reclist(
        xfs_mount_t             *mp,
        xfs_bmbt_rec_t          *rp,
-       int                     numrecs,
+       int                     *numrecs,
        int                     type,
        xfs_ino_t               ino,
        xfs_drfsbno_t           *tot,
@@ -863,7 +870,7 @@ int
 scan_bmbt_reclist(
        xfs_mount_t             *mp,
        xfs_bmbt_rec_t          *rp,
-       int                     numrecs,
+       int                     *numrecs,
        int                     type,
        xfs_ino_t               ino,
        xfs_drfsbno_t           *tot,
@@ -1356,23 +1363,29 @@ process_exinode(
        xfs_bmbt_rec_t          *rp;
        xfs_dfiloff_t           first_key;
        xfs_dfiloff_t           last_key;
+       int                     numrecs;
+       int                     ret;
 
        lino = XFS_AGINO_TO_INO(mp, agno, ino);
        rp = (xfs_bmbt_rec_t *)XFS_DFORK_PTR(dip, whichfork);
        *tot = 0;
-       *nex = XFS_DFORK_NEXTENTS(dip, whichfork);
+       numrecs = XFS_DFORK_NEXTENTS(dip, whichfork);
+
        /*
         * XXX - if we were going to fix up the btree record,
         * we'd do it right here.  For now, if there's a problem,
         * we'll bail out and presumably clear the inode.
         */
        if (check_dups == 0)
-               return(process_bmbt_reclist(mp, rp, *nex, type, lino,
+               ret = process_bmbt_reclist(mp, rp, &numrecs, type, lino,
                                        tot, blkmapp, &first_key, &last_key,
-                                       whichfork));
+                                       whichfork);
        else
-               return(scan_bmbt_reclist(mp, rp, *nex, type, lino, tot,
-                                       whichfork));
+               ret = scan_bmbt_reclist(mp, rp, &numrecs, type, lino, tot,
+                                       whichfork);
+
+       *nex = numrecs;
+       return ret;
 }
 
 /*
@@ -2063,6 +2076,17 @@ _("bad anextents %d for inode %" PRIu64
                                lino, anextents);
                }
        }
+
+       /*
+        * We are comparing different units here, but that's fine given that
+        * an extent has to have at least a block in it.
+        */
+       if (nblocks < nextents + anextents) {
+               do_warn(
+_("nblocks (%" PRIu64 ") smaller than nextents for inode %" PRIu64 "\n"), 
nblocks, lino);
+               return 1;
+       }
+
        return 0;
 }
 
Index: xfsprogs-dev/repair/dinode.h
===================================================================
--- xfsprogs-dev.orig/repair/dinode.h   2012-01-11 11:23:30.000000000 +0000
+++ xfsprogs-dev/repair/dinode.h        2012-02-02 11:17:38.000000000 +0000
@@ -42,7 +42,7 @@ convert_extent(
 int
 process_bmbt_reclist(xfs_mount_t       *mp,
                xfs_bmbt_rec_t          *rp,
-               int                     numrecs,
+               int                     *numrecs,
                int                     type,
                xfs_ino_t               ino,
                xfs_drfsbno_t           *tot,
@@ -55,7 +55,7 @@ int
 scan_bmbt_reclist(
        xfs_mount_t             *mp,
        xfs_bmbt_rec_t          *rp,
-       int                     numrecs,
+       int                     *numrecs,
        int                     type,
        xfs_ino_t               ino,
        xfs_drfsbno_t           *tot,
Index: xfsprogs-dev/repair/scan.c
===================================================================
--- xfsprogs-dev.orig/repair/scan.c     2012-01-11 11:23:30.000000000 +0000
+++ xfsprogs-dev/repair/scan.c  2012-02-02 11:17:38.000000000 +0000
@@ -351,12 +351,12 @@ _("inode %" PRIu64 " bad # of bmap recor
                 * we'll bail out and presumably clear the inode.
                 */
                if (check_dups == 0)  {
-                       err = process_bmbt_reclist(mp, rp, numrecs,
-                                       type, ino, tot, blkmapp,
-                                       &first_key, &last_key,
-                                       whichfork);
+                       err = process_bmbt_reclist(mp, rp, &numrecs, type, ino,
+                                                  tot, blkmapp, &first_key,
+                                                  &last_key, whichfork);
                        if (err)
-                               return(1);
+                               return 1;
+
                        /*
                         * check that key ordering is monotonically increasing.
                         * if the last_key value in the cursor is set to
@@ -380,10 +380,11 @@ _("out-of-order bmap key (file offset) i
                        bm_cursor->level[level].first_key = first_key;
                        bm_cursor->level[level].last_key = last_key;
 
-                       return(0);
-               } else
-                       return(scan_bmbt_reclist(mp, rp, numrecs,
-                                               type, ino, tot, whichfork));
+                       return 0;
+               } else {
+                       return scan_bmbt_reclist(mp, rp, &numrecs, type, ino,
+                                                tot, whichfork);
+               }
        }
        if (numrecs > mp->m_bmap_dmxr[1] || (isroot == 0 && numrecs <
                                                        mp->m_bmap_dmnr[1])) {

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