From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
If a caller supplies buffer ops when trying to read a buffer and the
buffer doesn't already have buf ops assigned, ensure that the ops are
assigned to the buffer and the verifier is run on that buffer.
Note that current XFS code is careful to assign buffer ops after a
xfs_{trans_,}buf_read call in which ops were not supplied. However, we
should apply ops defensively in case there is ever a coding mistake; and
an upcoming repair patch will need to be able to read a buffer without
assigning buf ops.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
fs/xfs/xfs_buf.c | 64 +++++++++++++++++++++++++++++++++++-------------
fs/xfs/xfs_buf.h | 3 ++
fs/xfs/xfs_trans_buf.c | 28 +++++++++++++++++++++
3 files changed, 78 insertions(+), 17 deletions(-)
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index e839907e8492..3adfa139dcfe 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -749,6 +749,29 @@ _xfs_buf_read(
return xfs_buf_submit(bp);
}
+/*
+ * If the caller passed in an ops structure and the buffer doesn't have ops
+ * assigned, set the ops and use them to verify the contents. If the contents
+ * cannot be verified, we'll clear XBF_DONE.
+ */
+int
+xfs_buf_ensure_ops(
+ struct xfs_buf *bp,
+ const struct xfs_buf_ops *ops)
+{
+ ASSERT(bp->b_flags & XBF_DONE);
+
+ if (!ops || bp->b_ops)
+ return 0;
+
+ bp->b_error = 0;
+ bp->b_ops = ops;
+ bp->b_ops->verify_read(bp);
+ if (bp->b_error)
+ bp->b_flags &= ~XBF_DONE;
+ return bp->b_error;
+}
+
xfs_buf_t *
xfs_buf_read_map(
struct xfs_buftarg *target,
@@ -762,26 +785,33 @@ xfs_buf_read_map(
flags |= XBF_READ;
bp = xfs_buf_get_map(target, map, nmaps, flags);
- if (bp) {
- trace_xfs_buf_read(bp, flags, _RET_IP_);
+ if (!bp)
+ return NULL;
- if (!(bp->b_flags & XBF_DONE)) {
- XFS_STATS_INC(target->bt_mount, xb_get_read);
- bp->b_ops = ops;
- _xfs_buf_read(bp, flags);
- } else if (flags & XBF_ASYNC) {
- /*
- * Read ahead call which is already satisfied,
- * drop the buffer
- */
- xfs_buf_relse(bp);
- return NULL;
- } else {
- /* We do not want read in the flags */
- bp->b_flags &= ~XBF_READ;
- }
+ trace_xfs_buf_read(bp, flags, _RET_IP_);
+
+ if (!(bp->b_flags & XBF_DONE)) {
+ XFS_STATS_INC(target->bt_mount, xb_get_read);
+ bp->b_ops = ops;
+ _xfs_buf_read(bp, flags);
+ ASSERT(bp->b_ops != NULL || ops == NULL);
+ return bp;
+ }
+
+ xfs_buf_ensure_ops(bp, ops);
+
+ if (flags & XBF_ASYNC) {
+ /*
+ * Read ahead call which is already satisfied,
+ * drop the buffer
+ */
+ xfs_buf_relse(bp);
+ return NULL;
}
+ /* We do not want read in the flags */
+ bp->b_flags &= ~XBF_READ;
+ ASSERT(bp->b_ops != NULL || ops == NULL);
return bp;
}
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 4e3171acd0f8..526bc7e9e7fc 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -385,4 +385,7 @@ extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int);
#define xfs_getsize_buftarg(buftarg) block_size((buftarg)->bt_bdev)
#define xfs_readonly_buftarg(buftarg) bdev_read_only((buftarg)->bt_bdev)
+extern int xfs_buf_ensure_ops(struct xfs_buf *bp,
+ const struct xfs_buf_ops *ops);
+
#endif /* __XFS_BUF_H__ */
diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c
index 15919f67a88f..b0ba2ca9cca3 100644
--- a/fs/xfs/xfs_trans_buf.c
+++ b/fs/xfs/xfs_trans_buf.c
@@ -264,11 +264,38 @@ xfs_trans_read_buf_map(
return -EIO;
}
+ /*
+ * The caller is trying to read a buffer that is already
+ * attached to the transaction yet has no buffer ops assigned.
+ * Ops are usually attached when the buffer is attached to the
+ * transaction, or by the read caller in special circumstances.
+ * That didn't happen, which is not how this is supposed to go.
+ *
+ * If the buffer passes verification we'll let this go, but if
+ * not we have to shut down. Let the transaction cleanup code
+ * release this buffer when it kills the tranaction.
+ */
+ ASSERT(bp->b_ops != NULL);
+ error = xfs_buf_ensure_ops(bp, ops);
+ if (error) {
+ xfs_buf_ioerror_alert(bp, __func__);
+
+ if (tp->t_flags & XFS_TRANS_DIRTY)
+ xfs_force_shutdown(tp->t_mountp,
+ SHUTDOWN_META_IO_ERROR);
+
+ /* bad CRC means corrupted metadata */
+ if (error == -EFSBADCRC)
+ error = -EFSCORRUPTED;
+ return error;
+ }
+
bip = bp->b_log_item;
bip->bli_recur++;
ASSERT(atomic_read(&bip->bli_refcount) > 0);
trace_xfs_trans_read_buf_recur(bip);
+ ASSERT(bp->b_ops != NULL || ops == NULL);
*bpp = bp;
return 0;
}
@@ -316,6 +343,7 @@ xfs_trans_read_buf_map(
_xfs_trans_bjoin(tp, bp, 1);
trace_xfs_trans_read_buf(bp->b_log_item);
}
+ ASSERT(bp->b_ops != NULL || ops == NULL);
*bpp = bp;
return 0;
