[PATCH] xfs: bulkstat doesn't release AGI buffer on error

[Brian Foster]

The recent refactoring of the bulkstat code left a small landmine in
the code. If a inobt read fails, then the tree walk is aborted and
returns without releasing the AGI buffer or freeing the cursor. This
can lead to a subsequent bulkstat call hanging trying to grab the
AGI buffer again.
---
fs/xfs/xfs_itable.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index f1deb96..ef8ea05 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -427,7 +427,7 @@ xfs_bulkstat(
error = xfs_bulkstat_grab_ichunk(cur, agino, &icount, &r);
if (error)
- break;
+ goto del_cursor;
if (icount) {
irbp->ir_startino = r.ir_startino;
irbp->ir_freecount = r.ir_freecount;
@@ -442,7 +442,7 @@ xfs_bulkstat(
error = xfs_inobt_lookup(cur, 0, XFS_LOOKUP_GE, &tmp);
}
if (error)
- break;
+ goto del_cursor;
/*
* Loop through inode btree records in this ag,
@@ -454,7 +454,7 @@ xfs_bulkstat(
error = xfs_inobt_get_rec(cur, &r, &i);
if (error || i == 0) {
end_of_ag = 1;
- break;
+ goto del_cursor;
}
/*
@@ -476,13 +476,17 @@ xfs_bulkstat(
error = xfs_btree_increment(cur, 0, &tmp);
cond_resched();
}
+
/*
- * Drop the btree buffers and the agi buffer.
- * We can't hold any of the locks these represent
- * when calling iget.
+ * Drop the btree buffers and the agi buffer as we can't hold any
+ * of the locks these represent when calling iget. If there is a
+ * pending error, then we are done.
*/
xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
xfs_buf_relse(agbp);
+ if (error)
+ break;
/*
* Now format all the good inodes into the user's buffer.
*/
--
2.0.0
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[Eric Sandeen]

The recent refactoring of the bulkstat code left a small landmine in
the code. If a inobt read fails, then the tree walk is aborted and
returns without releasing the AGI buffer or freeing the cursor. This
can lead to a subsequent bulkstat call hanging trying to grab the
AGI buffer again.

Reviewed-by: Eric Sandeen <***@redhat.com>

Can you add a cc: stable, too?

---
fs/xfs/xfs_itable.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index f1deb96..ef8ea05 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -427,7 +427,7 @@ xfs_bulkstat(
error = xfs_bulkstat_grab_ichunk(cur, agino, &icount, &r);
if (error)
- break;
+ goto del_cursor;
if (icount) {
irbp->ir_startino = r.ir_startino;
irbp->ir_freecount = r.ir_freecount;
@@ -442,7 +442,7 @@ xfs_bulkstat(
error = xfs_inobt_lookup(cur, 0, XFS_LOOKUP_GE, &tmp);
}
if (error)
- break;
+ goto del_cursor;
/*
* Loop through inode btree records in this ag,
@@ -454,7 +454,7 @@ xfs_bulkstat(
error = xfs_inobt_get_rec(cur, &r, &i);
if (error || i == 0) {
end_of_ag = 1;
- break;
+ goto del_cursor;
}
/*
@@ -476,13 +476,17 @@ xfs_bulkstat(
error = xfs_btree_increment(cur, 0, &tmp);
cond_resched();
}
+
/*
- * Drop the btree buffers and the agi buffer.
- * We can't hold any of the locks these represent
- * when calling iget.
+ * Drop the btree buffers and the agi buffer as we can't hold any
+ * of the locks these represent when calling iget. If there is a
+ * pending error, then we are done.
*/
xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
xfs_buf_relse(agbp);
+ if (error)
+ break;
/*
* Now format all the good inodes into the user's buffer.
*/