xfs: Check for extent overflow when trivally adding a new extent

mainline inclusion
from mainline-v5.12-rc1
commit 727e1acd
category: bugfix
bugzilla: 187510,https://gitee.com/openeuler/kernel/issues/I4KIAO

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=727e1acd297cae15449607d6e2ee39c71216cf1a

--------------------------------

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.
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NAllison Henderson <allison.henderson@oracle.com>
Signed-off-by: NChandan Babu R <chandanrlinux@gmail.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

Conflict: commit 3de4eb10 ("xfs: allow reservation of rtblocks with
xfs_trans_alloc_inode") is backported already, which introduce some
conflicts on code context.
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Signed-off-by: NGuo Xuenan <guoxuenan@huawei.com>
Reviewed-by: NZhang Yi <yi.zhang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

fs/xfs/libxfs/xfs_bmap.c

@@ -4516,6 +4516,12 @@ 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) ||

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.
  */

fs/xfs/xfs_bmap_item.c

@@ -497,6 +497,13 @@ xfs_bui_item_recover(
 	xfs_ilock(ip, XFS_ILOCK_EXCL);
 	xfs_trans_ijoin(tp, ip, 0);
 
+	if (bui_type == XFS_BMAP_MAP) {
+		error = xfs_iext_count_may_overflow(ip, whichfork,
+				XFS_IEXT_ADD_NOSPLIT_CNT);
+		if (error)
+			goto err_cancel;
+	}
+
 	count = bmap->me_len;
 	error = xfs_trans_log_finish_bmap_update(tp, budp, bui_type, ip,
 			whichfork, bmap->me_startoff, bmap->me_startblock,

fs/xfs/xfs_bmap_util.c

@@ -804,6 +804,10 @@ xfs_alloc_file_space(
 		if (error)
 			break;
 
+		error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
+				XFS_IEXT_ADD_NOSPLIT_CNT);
+		if (error)
+			goto error;
 
 		error = xfs_bmapi_write(tp, ip, startoffset_fsb,
 					allocatesize_fsb, alloc_type, 0, imapp,

fs/xfs/xfs_dquot.c

@@ -314,8 +314,14 @@ 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);

fs/xfs/xfs_iomap.c

@@ -241,6 +241,11 @@ xfs_iomap_write_direct(
 	if (error)
 		return error;
 
+	error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
+			XFS_IEXT_ADD_NOSPLIT_CNT);
+	if (error)
+		goto out_trans_cancel;
+
 	/*
 	 * From this point onwards we overwrite the imap pointer that the
 	 * caller gave to us.

fs/xfs/xfs_rtalloc.c

@@ -804,6 +804,11 @@ 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.
 		 */