The delwri queue mechanism does not provide the ability to
distinguish between stale (or lazily removed) buffers in a delwri
queue and buffers that have been submitted from a delwri queue and
sit on a wait list. Buffers in both cases have the _XBF_DELWRI_Q
flag cleared and ->b_list as a member of an associated list. This
means that a queue of a buffer cannot always tell if a buffer is
actually on a delwri queue if ->b_list is non-empty and
_XBF_DELWRI_Q is not already set.
Define a new flag for wait listed buffers to distinguish this case
and prepare to handle it properly. This patch defines, sets and
clears the _XBF_DELWRI_W flag at the appropriate places and
otherwise does not change behavior.
Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
---
fs/xfs/xfs_buf.c | 5 +++--
fs/xfs/xfs_buf.h | 4 +++-
2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 980bc48979e9..912cbbf44db7 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -2033,6 +2033,7 @@ xfs_buf_delwri_submit_buffers(
bp->b_flags &= ~(_XBF_DELWRI_Q | XBF_WRITE_FAIL);
bp->b_flags |= XBF_WRITE | XBF_ASYNC;
if (wait_list) {
+ bp->b_flags |= _XBF_DELWRI_W;
xfs_buf_hold(bp);
list_move_tail(&bp->b_list, wait_list);
} else
@@ -2083,10 +2084,10 @@ xfs_buf_delwri_submit(
while (!list_empty(&wait_list)) {
bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
- list_del_init(&bp->b_list);
-
/* locking the buffer will wait for async IO completion. */
xfs_buf_lock(bp);
+ bp->b_flags &= ~_XBF_DELWRI_W;
+ list_del_init(&bp->b_list);
error2 = bp->b_error;
xfs_buf_relse(bp);
if (!error)
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index d24dbd4dac39..07409b72dcad 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -50,7 +50,8 @@ typedef enum {
#define _XBF_PAGES (1 << 20)/* backed by refcounted pages */
#define _XBF_KMEM (1 << 21)/* backed by heap memory */
#define _XBF_DELWRI_Q (1 << 22)/* buffer on a delwri queue */
-#define _XBF_COMPOUND (1 << 23)/* compound buffer */
+#define _XBF_DELWRI_W (1 << 23)/* buffer on a delwri wait list */
+#define _XBF_COMPOUND (1 << 24)/* compound buffer */
typedef unsigned int xfs_buf_flags_t;
@@ -71,6 +72,7 @@ typedef unsigned int xfs_buf_flags_t;
{ _XBF_PAGES, "PAGES" }, \
{ _XBF_KMEM, "KMEM" }, \
{ _XBF_DELWRI_Q, "DELWRI_Q" }, \
+ { _XBF_DELWRI_W, "DELWRI_W" }, \
{ _XBF_COMPOUND, "COMPOUND" }
--
2.17.1
--
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