[PATCH 07/10] xfs: do not write the buffer from xfs_qm_dqflush

Christoph Hellwig
2012-03-27T16:46:48Z

[-- Attachment #1: xfs-dqflush-dont-write-buffer --]
[-- Type: text/plain, Size: 6612 bytes --]

Instead of writing the buffer directly from inside xfs_qm_dqflush return it
to the caller and let the caller decide what to do with the buffer. Also
remove the pincount check in xfs_qm_dqflush that all non-blocking callers
already implement and the now unused flags parameter and the XFS_DQ_IS_DIRTY
check that all callers already perform.

Signed-off-by: Christoph Hellwig <hch@lst.de>

---
fs/xfs/xfs_dquot.c | 43 +++++++++++++------------------------------
fs/xfs/xfs_dquot.h | 2 +-
fs/xfs/xfs_dquot_item.c | 21 +++++++++++++++++++--
fs/xfs/xfs_qm.c | 23 +++++++++++++++++++----
4 files changed, 52 insertions(+), 37 deletions(-)

Index: xfs/fs/xfs/xfs_dquot.c
===================================================================
--- xfs.orig/fs/xfs/xfs_dquot.c 2012-03-25 13:29:53.121004759 +0200
+++ xfs/fs/xfs/xfs_dquot.c 2012-03-25 13:36:25.947678708 +0200
@@ -878,8 +878,8 @@ xfs_qm_dqflush_done(
*/
int
xfs_qm_dqflush(
- xfs_dquot_t *dqp,
- uint flags)
+ struct xfs_dquot *dqp,
+ struct xfs_buf **bpp)
{
struct xfs_mount *mp = dqp->q_mount;
struct xfs_buf *bp;
@@ -891,14 +891,8 @@ xfs_qm_dqflush(

trace_xfs_dqflush(dqp);

- /*
- * If not dirty, or it's pinned and we are not supposed to block, nada.
- */
- if (!XFS_DQ_IS_DIRTY(dqp) ||
- ((flags & SYNC_TRYLOCK) && atomic_read(&dqp->q_pincount) > 0)) {
- xfs_dqfunlock(dqp);
- return 0;
- }
+ *bpp = NULL;
+
xfs_qm_dqunpin_wait(dqp);

/*
@@ -918,9 +912,8 @@ xfs_qm_dqflush(
xfs_trans_ail_delete(mp->m_ail, lip);
else
spin_unlock(&mp->m_ail->xa_lock);
-
- xfs_dqfunlock(dqp);
- return XFS_ERROR(EIO);
+ error = XFS_ERROR(EIO);
+ goto out_unlock;
}

/*
@@ -928,11 +921,8 @@ xfs_qm_dqflush(
*/
error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp, dqp->q_blkno,
mp->m_quotainfo->qi_dqchunklen, 0, &bp);
- if (error) {
- ASSERT(error != ENOENT);
- xfs_dqfunlock(dqp);
- return error;
- }
+ if (error)
+ goto out_unlock;

/*
* Calculate the location of the dquot inside the buffer.
@@ -978,20 +968,13 @@ xfs_qm_dqflush(
xfs_log_force(mp, 0);
}

- if (flags & SYNC_WAIT)
- error = xfs_bwrite(bp);
- else
- xfs_buf_delwri_queue(bp);
-
- xfs_buf_relse(bp);
-
trace_xfs_dqflush_done(dqp);
+ *bpp = bp;
+ return 0;

- /*
- * dqp is still locked, but caller is free to unlock it now.
- */
- return error;
-
+out_unlock:
+ xfs_dqfunlock(dqp);
+ return XFS_ERROR(EIO);
}

/*
Index: xfs/fs/xfs/xfs_dquot.h
===================================================================
--- xfs.orig/fs/xfs/xfs_dquot.h 2012-03-25 13:29:53.134338092 +0200
+++ xfs/fs/xfs/xfs_dquot.h 2012-03-25 13:31:55.844340367 +0200
@@ -141,7 +141,7 @@ static inline xfs_dquot_t *xfs_inode_dqu
extern int xfs_qm_dqread(struct xfs_mount *, xfs_dqid_t, uint,
uint, struct xfs_dquot **);
extern void xfs_qm_dqdestroy(xfs_dquot_t *);
-extern int xfs_qm_dqflush(xfs_dquot_t *, uint);
+extern int xfs_qm_dqflush(struct xfs_dquot *, struct xfs_buf **);
extern void xfs_qm_dqunpin_wait(xfs_dquot_t *);
extern void xfs_qm_adjust_dqtimers(xfs_mount_t *,
xfs_disk_dquot_t *);
Index: xfs/fs/xfs/xfs_dquot_item.c
===================================================================
--- xfs.orig/fs/xfs/xfs_dquot_item.c 2012-03-25 13:29:53.144338092 +0200
+++ xfs/fs/xfs/xfs_dquot_item.c 2012-03-25 13:36:38.981012285 +0200
@@ -119,10 +119,12 @@ xfs_qm_dquot_logitem_push(
struct xfs_log_item *lip)
{
struct xfs_dquot *dqp = DQUOT_ITEM(lip)->qli_dquot;
+ struct xfs_buf *bp = NULL;
int error;

ASSERT(XFS_DQ_IS_LOCKED(dqp));
ASSERT(!completion_done(&dqp->q_flush));
+ ASSERT(atomic_read(&dqp->q_pincount) == 0);

/*
* Since we were able to lock the dquot's flush lock and
@@ -133,10 +135,16 @@ xfs_qm_dquot_logitem_push(
* lock without sleeping, then there must not have been
* anyone in the process of flushing the dquot.
*/
- error = xfs_qm_dqflush(dqp, SYNC_TRYLOCK);
- if (error)
+ error = xfs_qm_dqflush(dqp, &bp);
+ if (error) {
xfs_warn(dqp->q_mount, "%s: push error %d on dqp %p",
__func__, error, dqp);
+ goto out_unlock;
+ }
+
+ xfs_buf_delwri_queue(bp);
+ xfs_buf_relse(bp);
+out_unlock:
xfs_dqunlock(dqp);
}

@@ -239,6 +247,15 @@ xfs_qm_dquot_logitem_trylock(
if (!xfs_dqlock_nowait(dqp))
return XFS_ITEM_LOCKED;

+ /*
+ * Re-check the pincount now that we stabilized the value by
+ * taking the quota lock.
+ */
+ if (atomic_read(&dqp->q_pincount) > 0) {
+ xfs_dqunlock(dqp);
+ return XFS_ITEM_PINNED;
+ }
+
if (!xfs_dqflock_nowait(dqp)) {
/*
* dquot has already been flushed to the backing buffer,
Index: xfs/fs/xfs/xfs_qm.c
===================================================================
--- xfs.orig/fs/xfs/xfs_qm.c 2012-03-25 13:29:53.161004759 +0200
+++ xfs/fs/xfs/xfs_qm.c 2012-03-25 13:36:22.031011971 +0200
@@ -175,16 +175,21 @@ xfs_qm_dqpurge(
* we're unmounting, we do care, so we flush it and wait.
*/
if (XFS_DQ_IS_DIRTY(dqp)) {
- int error;
+ struct xfs_buf *bp = NULL;
+ int error;

/*
* We don't care about getting disk errors here. We need
* to purge this dquot anyway, so we go ahead regardless.
*/
- error = xfs_qm_dqflush(dqp, SYNC_WAIT);
+ error = xfs_qm_dqflush(dqp, &bp);
if (error)
xfs_warn(mp, "%s: dquot %p flush failed",
__func__, dqp);
+ } else {
+ error = xfs_bwrite(bp);
+ xfs_buf_relse(bp);
+ }
xfs_dqflock(dqp);
}

@@ -1184,6 +1189,7 @@ STATIC int
xfs_qm_flush_one(
struct xfs_dquot *dqp)
{
+ struct xfs_buf *bp = NULL;
int error = 0;

xfs_dqlock(dqp);
@@ -1195,8 +1201,12 @@ xfs_qm_flush_one(
if (!xfs_dqflock_nowait(dqp))
xfs_dqflock_pushbuf_wait(dqp);

- error = xfs_qm_dqflush(dqp, 0);
+ error = xfs_qm_dqflush(dqp, &bp);
+ if (error)
+ goto out_unlock;

+ xfs_buf_delwri_queue(bp);
+ xfs_buf_relse(bp);
out_unlock:
xfs_dqunlock(dqp);
return error;
@@ -1463,18 +1473,23 @@ xfs_qm_dqreclaim_one(
* dirty dquots.
*/
if (XFS_DQ_IS_DIRTY(dqp)) {
+ struct xfs_buf *bp = NULL;
+
trace_xfs_dqreclaim_dirty(dqp);

/*
* We flush it delayed write, so don't bother releasing the
* freelist lock.
*/
- error = xfs_qm_dqflush(dqp, 0);
+ error = xfs_qm_dqflush(dqp, &bp);
if (error) {
xfs_warn(mp, "%s: dquot %p flush failed",
__func__, dqp);
+ goto out_busy;
}

+ xfs_buf_delwri_queue(bp);
+ xfs_buf_relse(bp);
/*
* Give the dquot another try on the freelist, as the
* flushing will take some time.