Merge tag 'xfs-for-linus-3.18-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs

Pull xfs fixes from Dave Chinner:
 "This update fixes a warning in the new pagecache_isize_extended() and
  updates some related comments, another fix for zero-range
  misbehaviour, and an unforntuately large set of fixes for regressions
  in the bulkstat code.

  The bulkstat fixes are large but necessary.  I wouldn't normally push
  such a rework for a -rcX update, but right now xfsdump can silently
  create incomplete dumps on 3.17 and it's possible that even xfsrestore
  won't notice that the dumps were incomplete.  Hence we need to get
  this update into 3.17-stable kernels ASAP.

  In more detail, the refactoring work I committed in 3.17 has exposed a
  major hole in our QA coverage.  With both xfsdump (the major user of
  bulkstat) and xfsrestore silently ignoring missing files in the
  dump/restore process, incomplete dumps were going unnoticed if they
  were being triggered.  Many of the dump/restore filesets were so small
  that they didn't evenhave a chance of triggering the loop iteration
  bugs we introduced in 3.17, so we didn't exercise the code
  sufficiently, either.

  We have already taken steps to improve QA coverage in xfstests to
  avoid this happening again, and I've done a lot of manual verification
  of dump/restore on very large data sets (tens of millions of inodes)
  of the past week to verify this patch set results in bulkstat behaving
  the same way as it does on 3.16.

  Unfortunately, the fixes are not exactly simple - in tracking down the
  problem historic API warts were discovered (e.g xfsdump has been
  working around a 20 year old bug in the bulkstat API for the past 10
  years) and so that complicated the process of diagnosing and fixing
  the problems.  i.e. we had to fix bugs in the code as well as
  discover and re-introduce the userspace visible API bugs that we
  unwittingly "fixed" in 3.17 that xfsdump relied on to work correctly.

  Summary:

   - incorrect warnings about i_mutex locking in pagecache_isize_extended()
     and updates comments to match expected locking
   - another zero-range bug fix for stray file size updates
   - a bunch of fixes for regression in the bulkstat code introduced in
     3.17"

* tag 'xfs-for-linus-3.18-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs:
  xfs: track bulkstat progress by agino
  xfs: bulkstat error handling is broken
  xfs: bulkstat main loop logic is a mess
  xfs: bulkstat chunk-formatter has issues
  xfs: bulkstat chunk formatting cursor is broken
  xfs: bulkstat btree walk doesn't terminate
  mm: Fix comment before truncate_setsize()
  xfs: rework zero range to prevent invalid i_size updates
  mm: Remove false WARN_ON from pagecache_isize_extended()
  xfs: Check error during inode btree iteration in xfs_bulkstat()
  xfs: bulkstat doesn't release AGI buffer on error

3 files changed, 142 insertions, 196 deletions

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 92e8f99a5857..281002689d64 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1338,7 +1338,10 @@ xfs_free_file_space(
         goto out;
 }
 
-
+/*
+ * Preallocate and zero a range of a file. This mechanism has the allocation
+ * semantics of fallocate and in addition converts data in the range to zeroes.
+ */
 int
 xfs_zero_file_space(
         struct xfs_inode        *ip,
@@ -1346,65 +1349,30 @@ xfs_zero_file_space(
         xfs_off_t               len)
 {
         struct xfs_mount        *mp = ip->i_mount;
-        uint                    granularity;
-        xfs_off_t               start_boundary;
-        xfs_off_t               end_boundary;
+        uint                    blksize;
         int                     error;
 
         trace_xfs_zero_file_space(ip);
 
-        granularity = max_t(uint, 1 << mp->m_sb.sb_blocklog, PAGE_CACHE_SIZE);
+        blksize = 1 << mp->m_sb.sb_blocklog;
 
         /*
-         * Round the range of extents we are going to convert inwards.  If the
-         * offset is aligned, then it doesn't get changed so we zero from the
-         * start of the block offset points to.
+         * Punch a hole and prealloc the range. We use hole punch rather than
+         * unwritten extent conversion for two reasons:
+         *
+         * 1.) Hole punch handles partial block zeroing for us.
+         *
+         * 2.) If prealloc returns ENOSPC, the file range is still zero-valued
+         * by virtue of the hole punch.
          */
-        start_boundary = round_up(offset, granularity);
-        end_boundary = round_down(offset + len, granularity);
-
-        ASSERT(start_boundary >= offset);
-        ASSERT(end_boundary <= offset + len);
-
-        if (start_boundary < end_boundary - 1) {
-                /*
-                 * Writeback the range to ensure any inode size updates due to
-                 * appending writes make it to disk (otherwise we could just
-                 * punch out the delalloc blocks).
-                 */
-                error = filemap_write_and_wait_range(VFS_I(ip)->i_mapping,
-                                start_boundary, end_boundary - 1);
-                if (error)
-                        goto out;
-                truncate_pagecache_range(VFS_I(ip), start_boundary,
-                                         end_boundary - 1);
-
-                /* convert the blocks */
-                error = xfs_alloc_file_space(ip, start_boundary,
-                                        end_boundary - start_boundary - 1,
-                                        XFS_BMAPI_PREALLOC | XFS_BMAPI_CONVERT);
-                if (error)
-                        goto out;
-
-                /* We've handled the interior of the range, now for the edges */
-                if (start_boundary != offset) {
-                        error = xfs_iozero(ip, offset, start_boundary - offset);
-                        if (error)
-                                goto out;
-                }
-
-                if (end_boundary != offset + len)
-                        error = xfs_iozero(ip, end_boundary,
-                                           offset + len - end_boundary);
-
-        } else {
-                /*
-                 * It's either a sub-granularity range or the range spanned lies
-                 * partially across two adjacent blocks.
-                 */
-                error = xfs_iozero(ip, offset, len);
-        }
+        error = xfs_free_file_space(ip, offset, len);
+        if (error)
+                goto out;
 
+        error = xfs_alloc_file_space(ip, round_down(offset, blksize),
+                                     round_up(offset + len, blksize) -
+                                     round_down(offset, blksize),
+                                     XFS_BMAPI_PREALLOC);
 out:
         return error;
 
diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index f1deb961a296..894924a5129b 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -236,8 +236,10 @@ xfs_bulkstat_grab_ichunk(
         XFS_WANT_CORRUPTED_RETURN(stat == 1);
 
         /* Check if the record contains the inode in request */
-        if (irec->ir_startino + XFS_INODES_PER_CHUNK <= agino)
-                return -EINVAL;
+        if (irec->ir_startino + XFS_INODES_PER_CHUNK <= agino) {
+                *icount = 0;
+                return 0;
+        }
 
         idx = agino - irec->ir_startino + 1;
         if (idx < XFS_INODES_PER_CHUNK &&
@@ -262,75 +264,76 @@ xfs_bulkstat_grab_ichunk(
 
 #define XFS_BULKSTAT_UBLEFT(ubleft)     ((ubleft) >= statstruct_size)
 
+struct xfs_bulkstat_agichunk {
+        char            __user **ac_ubuffer;/* pointer into user's buffer */
+        int             ac_ubleft;      /* bytes left in user's buffer */
+        int             ac_ubelem;      /* spaces used in user's buffer */
+};
+
 /*
  * Process inodes in chunk with a pointer to a formatter function
  * that will iget the inode and fill in the appropriate structure.
  */
-int
+static int
 xfs_bulkstat_ag_ichunk(
         struct xfs_mount                *mp,
         xfs_agnumber_t                  agno,
         struct xfs_inobt_rec_incore     *irbp,
         bulkstat_one_pf                 formatter,
         size_t                          statstruct_size,
-        struct xfs_bulkstat_agichunk    *acp)
+        struct xfs_bulkstat_agichunk    *acp,
+        xfs_agino_t                     *last_agino)
 {
-        xfs_ino_t                       lastino = acp->ac_lastino;
         char                            __user **ubufp = acp->ac_ubuffer;
-        int                             ubleft = acp->ac_ubleft;
-        int                             ubelem = acp->ac_ubelem;
-        int                             chunkidx, clustidx;
+        int                             chunkidx;
         int                             error = 0;
-        xfs_agino_t                     agino;
+        xfs_agino_t                     agino = irbp->ir_startino;
 
-        for (agino = irbp->ir_startino, chunkidx = clustidx = 0;
-             XFS_BULKSTAT_UBLEFT(ubleft) &&
-             irbp->ir_freecount < XFS_INODES_PER_CHUNK;
-             chunkidx++, clustidx++, agino++) {
-                int             fmterror;       /* bulkstat formatter result */
+        for (chunkidx = 0; chunkidx < XFS_INODES_PER_CHUNK;
+             chunkidx++, agino++) {
+                int             fmterror;
                 int             ubused;
-                xfs_ino_t       ino = XFS_AGINO_TO_INO(mp, agno, agino);
 
-                ASSERT(chunkidx < XFS_INODES_PER_CHUNK);
+                /* inode won't fit in buffer, we are done */
+                if (acp->ac_ubleft < statstruct_size)
+                        break;
 
                 /* Skip if this inode is free */
-                if (XFS_INOBT_MASK(chunkidx) & irbp->ir_free) {
-                        lastino = ino;
+                if (XFS_INOBT_MASK(chunkidx) & irbp->ir_free)
                         continue;
-                }
-
-                /*
-                 * Count used inodes as free so we can tell when the
-                 * chunk is used up.
-                 */
-                irbp->ir_freecount++;
 
                 /* Get the inode and fill in a single buffer */
                 ubused = statstruct_size;
-                error = formatter(mp, ino, *ubufp, ubleft, &ubused, &fmterror);
-                if (fmterror == BULKSTAT_RV_NOTHING) {
-                        if (error && error != -ENOENT && error != -EINVAL) {
-                                ubleft = 0;
-                                break;
-                        }
-                        lastino = ino;
-                        continue;
-                }
-                if (fmterror == BULKSTAT_RV_GIVEUP) {
-                        ubleft = 0;
+                error = formatter(mp, XFS_AGINO_TO_INO(mp, agno, agino),
+                                  *ubufp, acp->ac_ubleft, &ubused, &fmterror);
+
+                if (fmterror == BULKSTAT_RV_GIVEUP ||
+                    (error && error != -ENOENT && error != -EINVAL)) {
+                        acp->ac_ubleft = 0;
                         ASSERT(error);
                         break;
                 }
-                if (*ubufp)
-                        *ubufp += ubused;
-                ubleft -= ubused;
-                ubelem++;
-                lastino = ino;
+
+                /* be careful not to leak error if at end of chunk */
+                if (fmterror == BULKSTAT_RV_NOTHING || error) {
+                        error = 0;
+                        continue;
+                }
+
+                *ubufp += ubused;
+                acp->ac_ubleft -= ubused;
+                acp->ac_ubelem++;
         }
 
-        acp->ac_lastino = lastino;
-        acp->ac_ubleft = ubleft;
-        acp->ac_ubelem = ubelem;
+        /*
+         * Post-update *last_agino. At this point, agino will always point one
+         * inode past the last inode we processed successfully. Hence we
+         * substract that inode when setting the *last_agino cursor so that we
+         * return the correct cookie to userspace. On the next bulkstat call,
+         * the inode under the lastino cookie will be skipped as we have already
+         * processed it here.
+         */
+        *last_agino = agino - 1;
 
         return error;
 }
@@ -353,45 +356,33 @@ xfs_bulkstat(
         xfs_agino_t             agino;  /* inode # in allocation group */
         xfs_agnumber_t          agno;   /* allocation group number */
         xfs_btree_cur_t         *cur;   /* btree cursor for ialloc btree */
-        int                     end_of_ag; /* set if we've seen the ag end */
-        int                     error;  /* error code */
-        int                     fmterror;/* bulkstat formatter result */
-        int                     i;      /* loop index */
-        int                     icount; /* count of inodes good in irbuf */
         size_t                  irbsize; /* size of irec buffer in bytes */
-        xfs_ino_t               ino;    /* inode number (filesystem) */
-        xfs_inobt_rec_incore_t  *irbp;  /* current irec buffer pointer */
         xfs_inobt_rec_incore_t  *irbuf; /* start of irec buffer */
-        xfs_inobt_rec_incore_t  *irbufend; /* end of good irec buffer entries */
-        xfs_ino_t               lastino; /* last inode number returned */
         int                     nirbuf; /* size of irbuf */
-        int                     rval;   /* return value error code */
-        int                     tmp;    /* result value from btree calls */
         int                     ubcount; /* size of user's buffer */
-        int                     ubleft; /* bytes left in user's buffer */
-        char                    __user *ubufp;  /* pointer into user's buffer */
-        int                     ubelem; /* spaces used in user's buffer */
+        struct xfs_bulkstat_agichunk ac;
+        int                     error = 0;
 
         /*
          * Get the last inode value, see if there's nothing to do.
          */
-        ino = (xfs_ino_t)*lastinop;
-        lastino = ino;
-        agno = XFS_INO_TO_AGNO(mp, ino);
-        agino = XFS_INO_TO_AGINO(mp, ino);
+        agno = XFS_INO_TO_AGNO(mp, *lastinop);
+        agino = XFS_INO_TO_AGINO(mp, *lastinop);
         if (agno >= mp->m_sb.sb_agcount ||
-            ino != XFS_AGINO_TO_INO(mp, agno, agino)) {
+            *lastinop != XFS_AGINO_TO_INO(mp, agno, agino)) {
                 *done = 1;
                 *ubcountp = 0;
                 return 0;
         }
 
         ubcount = *ubcountp; /* statstruct's */
-        ubleft = ubcount * statstruct_size; /* bytes */
-        *ubcountp = ubelem = 0;
+        ac.ac_ubuffer = &ubuffer;
+        ac.ac_ubleft = ubcount * statstruct_size; /* bytes */;
+        ac.ac_ubelem = 0;
+
+        *ubcountp = 0;
         *done = 0;
-        fmterror = 0;
-        ubufp = ubuffer;
+
         irbuf = kmem_zalloc_greedy(&irbsize, PAGE_SIZE, PAGE_SIZE * 4);
         if (!irbuf)
                 return -ENOMEM;
@@ -402,9 +393,13 @@ xfs_bulkstat(
          * Loop over the allocation groups, starting from the last
          * inode returned; 0 means start of the allocation group.
          */
-        rval = 0;
-        while (XFS_BULKSTAT_UBLEFT(ubleft) && agno < mp->m_sb.sb_agcount) {
-                cond_resched();
+        while (agno < mp->m_sb.sb_agcount) {
+                struct xfs_inobt_rec_incore     *irbp = irbuf;
+                struct xfs_inobt_rec_incore     *irbufend = irbuf + nirbuf;
+                bool                            end_of_ag = false;
+                int                             icount = 0;
+                int                             stat;
+
                 error = xfs_ialloc_read_agi(mp, NULL, agno, &agbp);
                 if (error)
                         break;
@@ -414,10 +409,6 @@ xfs_bulkstat(
                  */
                 cur = xfs_inobt_init_cursor(mp, NULL, agbp, agno,
                                             XFS_BTNUM_INO);
-                irbp = irbuf;
-                irbufend = irbuf + nirbuf;
-                end_of_ag = 0;
-                icount = 0;
                 if (agino > 0) {
                         /*
                          * In the middle of an allocation group, we need to get
@@ -427,22 +418,23 @@ xfs_bulkstat(
 
                         error = xfs_bulkstat_grab_ichunk(cur, agino, &icount, &r);
                         if (error)
-                                break;
+                                goto del_cursor;
                         if (icount) {
                                 irbp->ir_startino = r.ir_startino;
                                 irbp->ir_freecount = r.ir_freecount;
                                 irbp->ir_free = r.ir_free;
                                 irbp++;
-                                agino = r.ir_startino + XFS_INODES_PER_CHUNK;
                         }
                         /* Increment to the next record */
-                        error = xfs_btree_increment(cur, 0, &tmp);
+                        error = xfs_btree_increment(cur, 0, &stat);
                 } else {
                         /* Start of ag.  Lookup the first inode chunk */
-                        error = xfs_inobt_lookup(cur, 0, XFS_LOOKUP_GE, &tmp);
+                        error = xfs_inobt_lookup(cur, 0, XFS_LOOKUP_GE, &stat);
+                }
+                if (error || stat == 0) {
+                        end_of_ag = true;
+                        goto del_cursor;
                 }
-                if (error)
-                        break;
 
                 /*
                  * Loop through inode btree records in this ag,
@@ -451,10 +443,10 @@ xfs_bulkstat(
                 while (irbp < irbufend && icount < ubcount) {
                         struct xfs_inobt_rec_incore     r;
 
-                        error = xfs_inobt_get_rec(cur, &r, &i);
-                        if (error || i == 0) {
-                                end_of_ag = 1;
-                                break;
+                        error = xfs_inobt_get_rec(cur, &r, &stat);
+                        if (error || stat == 0) {
+                                end_of_ag = true;
+                                goto del_cursor;
                         }
 
                         /*
@@ -469,77 +461,79 @@ xfs_bulkstat(
                                 irbp++;
                                 icount += XFS_INODES_PER_CHUNK - r.ir_freecount;
                         }
-                        /*
-                         * Set agino to after this chunk and bump the cursor.
-                         */
-                        agino = r.ir_startino + XFS_INODES_PER_CHUNK;
-                        error = xfs_btree_increment(cur, 0, &tmp);
+                        error = xfs_btree_increment(cur, 0, &stat);
+                        if (error || stat == 0) {
+                                end_of_ag = true;
+                                goto del_cursor;
+                        }
                         cond_resched();
                 }
+
                 /*
-                 * Drop the btree buffers and the agi buffer.
-                 * We can't hold any of the locks these represent
-                 * when calling iget.
+                 * Drop the btree buffers and the agi buffer as we can't hold any
+                 * of the locks these represent when calling iget. If there is a
+                 * pending error, then we are done.
                  */
+del_cursor:
                 xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
                 xfs_buf_relse(agbp);
+                if (error)
+                        break;
                 /*
-                 * Now format all the good inodes into the user's buffer.
+                 * Now format all the good inodes into the user's buffer. The
+                 * call to xfs_bulkstat_ag_ichunk() sets up the agino pointer
+                 * for the next loop iteration.
                  */
                 irbufend = irbp;
                 for (irbp = irbuf;
-                     irbp < irbufend && XFS_BULKSTAT_UBLEFT(ubleft); irbp++) {
-                        struct xfs_bulkstat_agichunk ac;
-
-                        ac.ac_lastino = lastino;
-                        ac.ac_ubuffer = &ubuffer;
-                        ac.ac_ubleft = ubleft;
-                        ac.ac_ubelem = ubelem;
+                     irbp < irbufend && ac.ac_ubleft >= statstruct_size;
+                     irbp++) {
                         error = xfs_bulkstat_ag_ichunk(mp, agno, irbp,
-                                        formatter, statstruct_size, &ac);
+                                        formatter, statstruct_size, &ac,
+                                        &agino);
                         if (error)
-                                rval = error;
-
-                        lastino = ac.ac_lastino;
-                        ubleft = ac.ac_ubleft;
-                        ubelem = ac.ac_ubelem;
+                                break;
 
                         cond_resched();
                 }
+
                 /*
-                 * Set up for the next loop iteration.
+                 * If we've run out of space or had a formatting error, we
+                 * are now done
                  */
-                if (XFS_BULKSTAT_UBLEFT(ubleft)) {
-                        if (end_of_ag) {
-                                agno++;
-                                agino = 0;
-                        } else
-                                agino = XFS_INO_TO_AGINO(mp, lastino);
-                } else
+                if (ac.ac_ubleft < statstruct_size || error)
                         break;
+
+                if (end_of_ag) {
+                        agno++;
+                        agino = 0;
+                }
         }
         /*
          * Done, we're either out of filesystem or space to put the data.
          */
         kmem_free(irbuf);
-        *ubcountp = ubelem;
+        *ubcountp = ac.ac_ubelem;
+
         /*
-         * Found some inodes, return them now and return the error next time.
+         * We found some inodes, so clear the error status and return them.
+         * The lastino pointer will point directly at the inode that triggered
+         * any error that occurred, so on the next call the error will be
+         * triggered again and propagated to userspace as there will be no
+         * formatted inodes in the buffer.
          */
-        if (ubelem)
-                rval = 0;
-        if (agno >= mp->m_sb.sb_agcount) {
-                /*
-                 * If we ran out of filesystem, mark lastino as off
-                 * the end of the filesystem, so the next call
-                 * will return immediately.
-                 */
-                *lastinop = (xfs_ino_t)XFS_AGINO_TO_INO(mp, agno, 0);
+        if (ac.ac_ubelem)
+                error = 0;
+
+        /*
+         * If we ran out of filesystem, lastino will point off the end of
+         * the filesystem so the next call will return immediately.
+         */
+        *lastinop = XFS_AGINO_TO_INO(mp, agno, agino);
+        if (agno >= mp->m_sb.sb_agcount)
                 *done = 1;
-        } else
-                *lastinop = (xfs_ino_t)lastino;
 
-        return rval;
+        return error;
 }
 
 int
diff --git a/fs/xfs/xfs_itable.h b/fs/xfs/xfs_itable.h
index aaed08022eb9..6ea8b3912fa4 100644
--- a/fs/xfs/xfs_itable.h
+++ b/fs/xfs/xfs_itable.h
@@ -30,22 +30,6 @@ typedef int (*bulkstat_one_pf)(struct xfs_mount	*mp,
                                int              *ubused,
                                int              *stat);
 
-struct xfs_bulkstat_agichunk {
-        xfs_ino_t       ac_lastino;     /* last inode returned */
-        char            __user **ac_ubuffer;/* pointer into user's buffer */
-        int             ac_ubleft;      /* bytes left in user's buffer */
-        int             ac_ubelem;      /* spaces used in user's buffer */
-};
-
-int
-xfs_bulkstat_ag_ichunk(
-        struct xfs_mount                *mp,
-        xfs_agnumber_t                  agno,
-        struct xfs_inobt_rec_incore     *irbp,
-        bulkstat_one_pf                 formatter,
-        size_t                          statstruct_size,
-        struct xfs_bulkstat_agichunk    *acp);
-
 /*
  * Values for stat return value.
  */