Re: [PATCH V7 05/14] xfs: Check for extent overflow when adding/removing dir entries

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On 10/18/20 11:40 PM, Chandan Babu R wrote:
Directory entry addition/removal can cause the following,
1. Data block can be added/removed.
    A new extent can cause extent count to increase by 1.
2. Free disk block can be added/removed.
    Same behaviour as described above for Data block.
3. Dabtree blocks.
    XFS_DA_NODE_MAXDEPTH blocks can be added. Each of these
    can be new extents. Hence extent count can increase by
    XFS_DA_NODE_MAXDEPTH.

Looks ok
Reviewed-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Chandan Babu R <chandanrlinux@xxxxxxxxx>
---
  fs/xfs/libxfs/xfs_inode_fork.h | 13 +++++++++++++
  fs/xfs/xfs_inode.c             | 27 +++++++++++++++++++++++++++
  fs/xfs/xfs_symlink.c           |  5 +++++
  3 files changed, 45 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 5de2f07d0dd5..fd93fdc67ee4 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -57,6 +57,19 @@ struct xfs_ifork {
  #define XFS_IEXT_ATTR_MANIP_CNT(rmt_blks) \
  	(XFS_DA_NODE_MAXDEPTH + max(1, rmt_blks))
+/*
+ * Directory entry addition/removal can cause the following,
+ * 1. Data block can be added/removed.
+ *    A new extent can cause extent count to increase by 1.
+ * 2. Free disk block can be added/removed.
+ *    Same behaviour as described above for Data block.
+ * 3. Dabtree blocks.
+ *    XFS_DA_NODE_MAXDEPTH blocks can be added. Each of these can be new
+ *    extents. Hence extent count can increase by XFS_DA_NODE_MAXDEPTH.
+ */
+#define XFS_IEXT_DIR_MANIP_CNT(mp) \
+	((XFS_DA_NODE_MAXDEPTH + 1 + 1) * (mp)->m_dir_geo->fsbcount)
+
  /*
   * Fork handling.
   */
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 2bfbcf28b1bd..5b41ffaf04d7 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1177,6 +1177,11 @@ xfs_create(
  	if (error)
  		goto out_trans_cancel;
+ error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK,
+			XFS_IEXT_DIR_MANIP_CNT(mp));
+	if (error)
+		goto out_trans_cancel;
+
  	/*
  	 * A newly created regular or special file just has one directory
  	 * entry pointing to them, but a directory also the "." entry
@@ -1393,6 +1398,11 @@ xfs_link(
  	xfs_trans_ijoin(tp, sip, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, tdp, XFS_ILOCK_EXCL);
+ error = xfs_iext_count_may_overflow(tdp, XFS_DATA_FORK,
+			XFS_IEXT_DIR_MANIP_CNT(mp));
+	if (error)
+		goto error_return;
+
  	/*
  	 * If we are using project inheritance, we only allow hard link
  	 * creation in our tree when the project IDs are the same; else
@@ -2861,6 +2871,11 @@ xfs_remove(
  	xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
+ error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK,
+			XFS_IEXT_DIR_MANIP_CNT(mp));
+	if (error)
+		goto out_trans_cancel;
+
  	/*
  	 * If we're removing a directory perform some additional validation.
  	 */
@@ -3221,6 +3236,18 @@ xfs_rename(
  	if (wip)
  		xfs_trans_ijoin(tp, wip, XFS_ILOCK_EXCL);
+ error = xfs_iext_count_may_overflow(src_dp, XFS_DATA_FORK,
+			XFS_IEXT_DIR_MANIP_CNT(mp));
+	if (error)
+		goto out_trans_cancel;
+
+	if (target_ip == NULL) {
+		error = xfs_iext_count_may_overflow(target_dp, XFS_DATA_FORK,
+				XFS_IEXT_DIR_MANIP_CNT(mp));
+		if (error)
+			goto out_trans_cancel;
+	}
+
  	/*
  	 * If we are using project inheritance, we only allow renames
  	 * into our tree when the project IDs are the same; else the
diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c
index 8e88a7ca387e..581a4032a817 100644
--- a/fs/xfs/xfs_symlink.c
+++ b/fs/xfs/xfs_symlink.c
@@ -220,6 +220,11 @@ xfs_symlink(
  	if (error)
  		goto out_trans_cancel;
+ error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK,
+			XFS_IEXT_DIR_MANIP_CNT(mp));
+	if (error)
+		goto out_trans_cancel;
+
  	/*
  	 * Allocate an inode for the symlink.
  	 */




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