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

1 files changed, 20 insertions, 52 deletions

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 92e8f99a585..281002689d6 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;