[PATCH V3 02/10] xfs: Check for extent overflow when trivally adding a new extent

[Chandan Babu R <chandanrlinux@gmail.com>]

When adding a new data extent (without modifying an inode's existing
extents) the extent count increases only by 1. This commit checks for
extent count overflow in such cases.

Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
---
 fs/xfs/libxfs/xfs_bmap.c       | 6 ++++++
 fs/xfs/libxfs/xfs_inode_fork.h | 6 ++++++
 fs/xfs/xfs_bmap_util.c         | 5 +++++
 fs/xfs/xfs_dquot.c             | 8 +++++++-
 fs/xfs/xfs_iomap.c             | 5 +++++
 fs/xfs/xfs_rtalloc.c           | 5 +++++
 6 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 9c40d5971035..dcc8eeecd571 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -4527,6 +4527,12 @@ xfs_bmapi_convert_delalloc(
 		return error;
 
 	xfs_ilock(ip, XFS_ILOCK_EXCL);
+
+	error = xfs_iext_count_may_overflow(ip, whichfork,
+			XFS_IEXT_ADD_NOSPLIT_CNT);
+	if (error)
+		goto out_trans_cancel;
+
 	xfs_trans_ijoin(tp, ip, 0);
 
 	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &bma.icur, &bma.got) ||
diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 0beb8e2a00be..7fc2b129a2e7 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -34,6 +34,12 @@ struct xfs_ifork {
 #define	XFS_IFEXTENTS	0x02	/* All extent pointers are read in */
 #define	XFS_IFBROOT	0x04	/* i_broot points to the bmap b-tree root */
 
+/*
+ * Worst-case increase in the fork extent count when we're adding a single
+ * extent to a fork and there's no possibility of splitting an existing mapping.
+ */
+#define XFS_IEXT_ADD_NOSPLIT_CNT	(1)
+
 /*
  * Fork handling.
  */
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index afdc7f8e0e70..7b76a48b0885 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -822,6 +822,11 @@ xfs_alloc_file_space(
 		if (error)
 			goto error1;
 
+		error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
+				XFS_IEXT_ADD_NOSPLIT_CNT);
+		if (error)
+			goto error0;
+
 		xfs_trans_ijoin(tp, ip, 0);
 
 		error = xfs_bmapi_write(tp, ip, startoffset_fsb,
diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index 04dc2be19c3a..59ea9485ebda 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -290,8 +290,14 @@ xfs_dquot_disk_alloc(
 		return -ESRCH;
 	}
 
-	/* Create the block mapping. */
 	xfs_trans_ijoin(tp, quotip, XFS_ILOCK_EXCL);
+
+	error = xfs_iext_count_may_overflow(quotip, XFS_DATA_FORK,
+			XFS_IEXT_ADD_NOSPLIT_CNT);
+	if (error)
+		return error;
+
+	/* Create the block mapping. */
 	error = xfs_bmapi_write(tp, quotip, dqp->q_fileoffset,
 			XFS_DQUOT_CLUSTER_SIZE_FSB, XFS_BMAPI_METADATA, 0, &map,
 			&nmaps);
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 0e3f62cde375..37b0c743c116 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -250,6 +250,11 @@ xfs_iomap_write_direct(
 	if (error)
 		goto out_trans_cancel;
 
+	error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
+			XFS_IEXT_ADD_NOSPLIT_CNT);
+	if (error)
+		goto out_trans_cancel;
+
 	xfs_trans_ijoin(tp, ip, 0);
 
 	/*
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 6209e7b6b895..9508ab00a00b 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -787,6 +787,11 @@ xfs_growfs_rt_alloc(
 		xfs_ilock(ip, XFS_ILOCK_EXCL);
 		xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 
+		error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
+				XFS_IEXT_ADD_NOSPLIT_CNT);
+		if (error)
+			goto out_trans_cancel;
+
 		/*
 		 * Allocate blocks to the bitmap file.
 		 */
-- 
2.28.0