xfs: introduce a new xfs_inode_has_cow_data helper

We have a few places that already check if an inode has actual data in
the COW fork to avoid work on reflink inodes that do not actually have
outstanding COW blocks.  There are a few more places that can avoid
working if doing the same check, so add a documented helper for this
condition and use it in all places where it makes sense.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

6 files changed, 18 insertions, 12 deletions

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index f4d3252236c1..814100d27343 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -338,7 +338,7 @@ xfs_map_blocks(
 	imap_valid = offset_fsb >= wpc->imap.br_startoff &&
 		     offset_fsb < wpc->imap.br_startoff + wpc->imap.br_blockcount;
 	if (imap_valid &&
-	    (!xfs_is_reflink_inode(ip) || wpc->io_type == XFS_IO_COW))
+	    (!xfs_inode_has_cow_data(ip) || wpc->io_type == XFS_IO_COW))
 		return 0;
 
 	if (XFS_FORCED_SHUTDOWN(mp))
@@ -363,7 +363,7 @@ xfs_map_blocks(
 	 * Check if this is offset is covered by a COW extents, and if yes use
 	 * it directly instead of looking up anything in the data fork.
 	 */
-	if (xfs_is_reflink_inode(ip) &&
+	if (xfs_inode_has_cow_data(ip) &&
 	    xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &imap) &&
 	    imap.br_startoff <= offset_fsb) {
 		xfs_iunlock(ip, XFS_ILOCK_SHARED);
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index c32ec17048f5..412dc58ae54d 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1263,7 +1263,7 @@ xfs_prepare_shift(
 	 * we've flushed all the dirty data out to disk to avoid having
 	 * CoW extents at the wrong offsets.
 	 */
-	if (xfs_is_reflink_inode(ip)) {
+	if (xfs_inode_has_cow_data(ip)) {
 		error = xfs_reflink_cancel_cow_range(ip, offset, NULLFILEOFF,
 				true);
 		if (error)
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index e5591f5ebe15..245483cc282b 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -1697,14 +1697,13 @@ xfs_inode_clear_eofblocks_tag(
  */
 static bool
 xfs_prep_free_cowblocks(
-	struct xfs_inode	*ip,
-	struct xfs_ifork	*ifp)
+	struct xfs_inode	*ip)
 {
 	/*
 	 * Just clear the tag if we have an empty cow fork or none at all. It's
 	 * possible the inode was fully unshared since it was originally tagged.
 	 */
-	if (!xfs_is_reflink_inode(ip) || !ifp->if_bytes) {
+	if (!xfs_inode_has_cow_data(ip)) {
 		trace_xfs_inode_free_cowblocks_invalid(ip);
 		xfs_inode_clear_cowblocks_tag(ip);
 		return false;
@@ -1742,11 +1741,10 @@ xfs_inode_free_cowblocks(
 	void			*args)
 {
 	struct xfs_eofblocks	*eofb = args;
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 	int			match;
 	int			ret = 0;
 
-	if (!xfs_prep_free_cowblocks(ip, ifp))
+	if (!xfs_prep_free_cowblocks(ip))
 		return 0;
 
 	if (eofb) {
@@ -1771,7 +1769,7 @@ xfs_inode_free_cowblocks(
 	 * Check again, nobody else should be able to dirty blocks or change
 	 * the reflink iflag now that we have the first two locks held.
 	 */
-	if (xfs_prep_free_cowblocks(ip, ifp))
+	if (xfs_prep_free_cowblocks(ip))
 		ret = xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF, false);
 
 	xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 54fcfdfc748c..5fc1815c2b62 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1832,7 +1832,6 @@ xfs_inactive(
 	xfs_inode_t	*ip)
 {
 	struct xfs_mount	*mp;
-	struct xfs_ifork	*cow_ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 	int			error;
 	int			truncate = 0;
 
@@ -1853,7 +1852,7 @@ xfs_inactive(
 		return;
 
 	/* Try to clean out the cow blocks if there are any. */
-	if (xfs_is_reflink_inode(ip) && cow_ifp->if_bytes > 0)
+	if (xfs_inode_has_cow_data(ip))
 		xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF, true);
 
 	if (VFS_I(ip)->i_nlink != 0) {
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index a67efdac70a6..79a3e61a6991 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -199,6 +199,15 @@ static inline bool xfs_is_reflink_inode(struct xfs_inode *ip)
 }
 
 /*
+ * Check if an inode has any data in the COW fork.  This might be often false
+ * even for inodes with the reflink flag when there is no pending COW operation.
+ */
+static inline bool xfs_inode_has_cow_data(struct xfs_inode *ip)
+{
+	return ip->i_cowfp && ip->i_cowfp->if_bytes;
+}
+
+/*
  * In-core inode flags.
  */
 #define XFS_IRECLAIM		(1 << 0) /* started reclaiming this inode */
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 68b6921dc3f6..9a0a56526266 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -478,7 +478,7 @@ xfs_reflink_cancel_cow_blocks(
 	struct xfs_iext_cursor		icur;
 	int				error = 0;
 
-	if (!xfs_is_reflink_inode(ip))
+	if (!xfs_inode_has_cow_data(ip))
 		return 0;
 	if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
 		return 0;