[Cluster-devel] [PATCH 2/2] gfs2: Add support for IOMAP_ZERO

[Andreas Gruenbacher <agruenba@redhat.com>]

Add support for the IOMAP_ZERO flag, which indicates a request to write
zeroes into a file without filling holes.  Used by iomap_zero_range.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/gfs2/bmap.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index e2c58c6a1276..aabd78a1ae59 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -1029,7 +1029,7 @@ static int __gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
 	iomap->flags |= IOMAP_F_BUFFER_HEAD;
 
 	ret = gfs2_iomap_get(inode, pos, length, flags, iomap, mp);
-	if (ret || !(flags & IOMAP_WRITE))
+	if (ret || !(flags & (IOMAP_WRITE | IOMAP_ZERO)))
 		return ret;
 	if (flags & IOMAP_DIRECT) {
 		/*
@@ -1040,6 +1040,10 @@ static int __gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
 			return -ENOTBLK;
 		return 0;
 	}
+	if (flags & IOMAP_ZERO) {
+		if (iomap->type == IOMAP_HOLE)
+			return 0;
+	}
 
 	unstuff = gfs2_is_stuffed(ip) &&
 		  pos + length > gfs2_max_stuffed_size(ip);
@@ -1156,8 +1160,12 @@ static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length,
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_sbd *sdp = GFS2_SB(inode);
 
-	if (!(flags & IOMAP_WRITE) || (flags & IOMAP_DIRECT))
+	if (!(flags & (IOMAP_WRITE | IOMAP_ZERO)) || (flags & IOMAP_DIRECT))
 		goto out;
+	if (flags & IOMAP_ZERO) {
+		if (iomap->type == IOMAP_HOLE)
+			goto out;
+	}
 
 	if (!gfs2_is_stuffed(ip))
 		gfs2_ordered_add_inode(ip);
@@ -1181,7 +1189,8 @@ static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length,
 
 	if (ip->i_qadata && ip->i_qadata->qa_qd_num)
 		gfs2_quota_unlock(ip);
-	gfs2_write_unlock(inode);
+	if (flags & IOMAP_WRITE)
+		gfs2_write_unlock(inode);
 
 out:
 	return 0;
-- 
2.20.1