[PATCH v6 03/10] xfs: create helper to check whether to free eofblocks on inode

[Brian Foster <bfoster@redhat.com>]

This check is used in multiple places to determine whether we
should check for (and potentially free) post EOF blocks on an
inode. Add a helper to consolidate the check.

Note that when we remove an inode from the cache (xfs_inactive()),
we are required to trim post-EOF blocks even if the inode is marked
preallocated or append-only to maintain correct space accounting.
The 'force' parameter to xfs_can_free_eofblocks() specifies whether
we should ignore the prealloc/append-only status of the inode.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely<tinguely@sgi.com>
---
 fs/xfs/xfs_inode.c    |   37 +++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_inode.h    |    1 +
 fs/xfs/xfs_vnodeops.c |   19 +++++++------------
 3 files changed, 45 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 95f7a73..cc7468b 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -3911,3 +3911,40 @@ xfs_iext_irec_update_extoffs(
 		ifp->if_u1.if_ext_irec[i].er_extoff += ext_diff;
 	}
 }
+
+/*
+ * Test whether it is appropriate to check an inode for and free post EOF
+ * blocks. The 'force' parameter determines whether we should also consider
+ * regular files that are marked preallocated or append-only.
+ */
+bool
+xfs_can_free_eofblocks(struct xfs_inode *ip, bool force)
+{
+	/* prealloc/delalloc exists only on regular files */
+	if (!S_ISREG(ip->i_d.di_mode))
+		return false;
+
+	/*
+	 * Zero sized files with no cached pages and delalloc blocks will not
+	 * have speculative prealloc/delalloc blocks to remove.
+	 */
+	if (VFS_I(ip)->i_size == 0 &&
+	    VN_CACHED(VFS_I(ip)) == 0 &&
+	    ip->i_delayed_blks == 0)
+		return false;
+
+	/* If we haven't read in the extent list, then don't do it now. */
+	if (!(ip->i_df.if_flags & XFS_IFEXTENTS))
+		return false;
+
+	/*
+	 * Do not free real preallocated or append-only files unless the file
+	 * has delalloc blocks and we are forced to remove them.
+	 */
+	if (ip->i_d.di_flags & (XFS_DIFLAG_PREALLOC | XFS_DIFLAG_APPEND))
+		if (!force || ip->i_delayed_blks == 0)
+			return false;
+
+	return true;
+}
+
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 1fc2065..21b4de3 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -585,6 +585,7 @@ void		xfs_iext_irec_compact(xfs_ifork_t *);
 void		xfs_iext_irec_compact_pages(xfs_ifork_t *);
 void		xfs_iext_irec_compact_full(xfs_ifork_t *);
 void		xfs_iext_irec_update_extoffs(xfs_ifork_t *, int, int);
+bool		xfs_can_free_eofblocks(struct xfs_inode *, bool);
 
 #define xfs_ipincount(ip)	((unsigned int) atomic_read(&ip->i_pincount))
 
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index e6e1d11..c4c1539 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -436,11 +436,7 @@ xfs_release(
 	if (ip->i_d.di_nlink == 0)
 		return 0;
 
-	if ((S_ISREG(ip->i_d.di_mode) &&
-	     (VFS_I(ip)->i_size > 0 ||
-	      (VN_CACHED(VFS_I(ip)) > 0 || ip->i_delayed_blks > 0)) &&
-	     (ip->i_df.if_flags & XFS_IFEXTENTS))  &&
-	    (!(ip->i_d.di_flags & (XFS_DIFLAG_PREALLOC | XFS_DIFLAG_APPEND)))) {
+	if (xfs_can_free_eofblocks(ip, false)) {
 
 		/*
 		 * If we can't get the iolock just skip truncating the blocks
@@ -516,13 +512,12 @@ xfs_inactive(
 		goto out;
 
 	if (ip->i_d.di_nlink != 0) {
-		if ((S_ISREG(ip->i_d.di_mode) &&
-		    (VFS_I(ip)->i_size > 0 ||
-		     (VN_CACHED(VFS_I(ip)) > 0 || ip->i_delayed_blks > 0)) &&
-		    (ip->i_df.if_flags & XFS_IFEXTENTS) &&
-		    (!(ip->i_d.di_flags &
-				(XFS_DIFLAG_PREALLOC | XFS_DIFLAG_APPEND)) ||
-		     ip->i_delayed_blks != 0))) {
+		/*
+		 * force is true because we are evicting an inode from the
+		 * cache. Post-eof blocks must be freed, lest we end up with
+		 * broken free space accounting.
+		 */
+		if (xfs_can_free_eofblocks(ip, true)) {
 			error = xfs_free_eofblocks(mp, ip, false);
 			if (error)
 				return VN_INACTIVE_CACHE;
-- 
1.7.7.6

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