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From: Dave Chinner <david@fromorbit.com>
To: linux-xfs@vger.kernel.org
Subject: [PATCH 20/24] xfs: xfs_iflush() is no longer necessary
Date: Fri, 22 May 2020 13:50:25 +1000
Message-ID: <20200522035029.3022405-21-david@fromorbit.com> (raw)
In-Reply-To: <20200522035029.3022405-1-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

Now we have a cached buffer on inode log items, we don't need
to do buffer lookups when flushing inodes anymore - all we need
to do is lock the buffer and we are ready to go.

This largely gets rid of the need for xfs_iflush(), which is
essentially just a mechanism to look up the buffer and flush the
inode to it. Instead, we can just call xfs_iflush_cluster() with a
few modifications to ensure it also flushes the inode we already
hold locked.

This allows the AIL inode item pushing to be almost entirely
non-blocking in XFS - we won't block unless memory allocation
for the cluster inode lookup blocks or the block device queues are
full.

Writeback during inode reclaim becomes a little more complex because
we now have to lock the buffer ourselves, but otherwise this change
is largely a functional no-op that removes a whole lot of code.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_inode.c      | 106 ++++++----------------------------------
 fs/xfs/xfs_inode.h      |   2 +-
 fs/xfs/xfs_inode_item.c |  51 +++++++------------
 3 files changed, 32 insertions(+), 127 deletions(-)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 961eef2ce8c4a..a94528d26328b 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -3429,7 +3429,18 @@ xfs_rename(
 	return error;
 }
 
-STATIC int
+/*
+ * Non-blocking flush of dirty inode metadata into the backing buffer.
+ *
+ * The caller must have a reference to the inode and hold the cluster buffer
+ * locked. The function will walk across all the inodes on the cluster buffer it
+ * can find and lock without blocking, and flush them to the cluster buffer.
+ *
+ * On success, the caller must write out the buffer returned in *bp and
+ * release it. On failure, the filesystem will be shut down, the buffer will
+ * have been unlocked and released, and EFSCORRUPTED will be returned.
+ */
+int
 xfs_iflush_cluster(
 	struct xfs_inode	*ip,
 	struct xfs_buf		*bp)
@@ -3464,8 +3475,6 @@ xfs_iflush_cluster(
 
 	for (i = 0; i < nr_found; i++) {
 		cip = cilist[i];
-		if (cip == ip)
-			continue;
 
 		/*
 		 * because this is an RCU protected lookup, we could find a
@@ -3556,99 +3565,11 @@ xfs_iflush_cluster(
 	kmem_free(cilist);
 out_put:
 	xfs_perag_put(pag);
-	return error;
-}
-
-/*
- * Flush dirty inode metadata into the backing buffer.
- *
- * The caller must have the inode lock and the inode flush lock held.  The
- * inode lock will still be held upon return to the caller, and the inode
- * flush lock will be released after the inode has reached the disk.
- *
- * The caller must write out the buffer returned in *bpp and release it.
- */
-int
-xfs_iflush(
-	struct xfs_inode	*ip,
-	struct xfs_buf		**bpp)
-{
-	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_buf		*bp = NULL;
-	struct xfs_dinode	*dip;
-	int			error;
-
-	XFS_STATS_INC(mp, xs_iflush_count);
-
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
-	ASSERT(xfs_isiflocked(ip));
-	ASSERT(ip->i_df.if_format != XFS_DINODE_FMT_BTREE ||
-	       ip->i_df.if_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));
-
-	*bpp = NULL;
-
-	xfs_iunpin_wait(ip);
-
-	/*
-	 * For stale inodes we cannot rely on the backing buffer remaining
-	 * stale in cache for the remaining life of the stale inode and so
-	 * xfs_imap_to_bp() below may give us a buffer that no longer contains
-	 * inodes below. We have to check this after ensuring the inode is
-	 * unpinned so that it is safe to reclaim the stale inode after the
-	 * flush call.
-	 */
-	if (xfs_iflags_test(ip, XFS_ISTALE)) {
-		xfs_ifunlock(ip);
-		return 0;
-	}
-
-	/*
-	 * Get the buffer containing the on-disk inode. We are doing a try-lock
-	 * operation here, so we may get an EAGAIN error. In that case, return
-	 * leaving the inode dirty.
-	 *
-	 * If we get any other error, we effectively have a corruption situation
-	 * and we cannot flush the inode. Abort the flush and shut down.
-	 */
-	error = xfs_imap_to_bp(mp, NULL, &ip->i_imap, &dip, &bp, XBF_TRYLOCK);
-	if (error == -EAGAIN) {
-		xfs_ifunlock(ip);
-		return error;
-	}
-	if (error)
-		goto abort;
-
-	/*
-	 * If the buffer is pinned then push on the log now so we won't
-	 * get stuck waiting in the write for too long.
-	 */
-	if (xfs_buf_ispinned(bp))
-		xfs_log_force(mp, 0);
-
-	/*
-	 * Flush the provided inode then attempt to gather others from the
-	 * cluster into the write.
-	 *
-	 * Note: Once we attempt to flush an inode, we must run buffer
-	 * completion callbacks on any failure. If this fails, simulate an I/O
-	 * failure on the buffer and shut down.
-	 */
-	error = xfs_iflush_int(ip, bp);
-	if (!error)
-		error = xfs_iflush_cluster(ip, bp);
 	if (error) {
 		bp->b_flags |= XBF_ASYNC;
 		xfs_buf_ioend_fail(bp);
-		goto shutdown;
+		xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
 	}
-
-	*bpp = bp;
-	return 0;
-
-abort:
-	xfs_iflush_abort(ip);
-shutdown:
-	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
 	return error;
 }
 
@@ -3667,6 +3588,7 @@ xfs_iflush_int(
 	ASSERT(ip->i_df.if_format != XFS_DINODE_FMT_BTREE ||
 	       ip->i_df.if_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));
 	ASSERT(iip != NULL && iip->ili_fields != 0);
+	ASSERT(iip->ili_item.li_buf == bp);
 
 	dip = xfs_buf_offset(bp, ip->i_imap.im_boffset);
 
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index dadcf19458960..d1109eb13ba2e 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -427,7 +427,7 @@ int		xfs_log_force_inode(struct xfs_inode *ip);
 void		xfs_iunpin_wait(xfs_inode_t *);
 #define xfs_ipincount(ip)	((unsigned int) atomic_read(&ip->i_pincount))
 
-int		xfs_iflush(struct xfs_inode *, struct xfs_buf **);
+int		xfs_iflush_cluster(struct xfs_inode *, struct xfs_buf *);
 void		xfs_lock_two_inodes(struct xfs_inode *ip0, uint ip0_mode,
 				struct xfs_inode *ip1, uint ip1_mode);
 
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index 7718cfc39eec8..42b4b5fe1e2a9 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -504,53 +504,35 @@ xfs_inode_item_push(
 	uint			rval = XFS_ITEM_SUCCESS;
 	int			error;
 
-	if (xfs_ipincount(ip) > 0)
-		return XFS_ITEM_PINNED;
+	ASSERT(iip->ili_item.li_buf);
 
-	if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED))
-		return XFS_ITEM_LOCKED;
+	if (xfs_ipincount(ip) > 0 || xfs_buf_ispinned(bp) ||
+	    (ip->i_flags & XFS_ISTALE))
+		return XFS_ITEM_PINNED;
 
-	/*
-	 * Re-check the pincount now that we stabilized the value by
-	 * taking the ilock.
-	 */
-	if (xfs_ipincount(ip) > 0) {
-		rval = XFS_ITEM_PINNED;
-		goto out_unlock;
-	}
+	/* If the inode is already flush locked, we're already flushing. */
+	if (xfs_isiflocked(ip))
+		return XFS_ITEM_FLUSHING;
 
-	/*
-	 * Stale inode items should force out the iclog.
-	 */
-	if (ip->i_flags & XFS_ISTALE) {
-		rval = XFS_ITEM_PINNED;
-		goto out_unlock;
-	}
+	if (!xfs_buf_trylock(bp))
+		return XFS_ITEM_LOCKED;
 
-	/*
-	 * Someone else is already flushing the inode.  Nothing we can do
-	 * here but wait for the flush to finish and remove the item from
-	 * the AIL.
-	 */
-	if (!xfs_iflock_nowait(ip)) {
-		rval = XFS_ITEM_FLUSHING;
-		goto out_unlock;
+	if (bp->b_flags & _XBF_DELWRI_Q) {
+		xfs_buf_unlock(bp);
+		return XFS_ITEM_FLUSHING;
 	}
-
-	ASSERT(iip->ili_fields != 0 || XFS_FORCED_SHUTDOWN(ip->i_mount));
 	spin_unlock(&lip->li_ailp->ail_lock);
 
-	error = xfs_iflush(ip, &bp);
+	error = xfs_iflush_cluster(ip, bp);
 	if (!error) {
 		if (!xfs_buf_delwri_queue(bp, buffer_list))
 			rval = XFS_ITEM_FLUSHING;
-		xfs_buf_relse(bp);
-	} else if (error == -EAGAIN)
+		xfs_buf_unlock(bp);
+	} else {
 		rval = XFS_ITEM_LOCKED;
+	}
 
 	spin_lock(&lip->li_ailp->ail_lock);
-out_unlock:
-	xfs_iunlock(ip, XFS_ILOCK_SHARED);
 	return rval;
 }
 
@@ -567,6 +549,7 @@ xfs_inode_item_release(
 
 	ASSERT(ip->i_itemp != NULL);
 	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	ASSERT(lip->li_buf || !test_bit(XFS_LI_DIRTY, &lip->li_flags));
 
 	lock_flags = iip->ili_lock_flags;
 	iip->ili_lock_flags = 0;
-- 
2.26.2.761.g0e0b3e54be


  parent reply index

Thread overview: 91+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-22  3:50 [PATCH 00/24] xfs: rework inode flushing to make inode reclaim fully asynchronous Dave Chinner
2020-05-22  3:50 ` [PATCH 01/24] xfs: remove logged flag from inode log item Dave Chinner
2020-05-22  7:25   ` Christoph Hellwig
2020-05-22 21:13   ` Darrick J. Wong
2020-05-22  3:50 ` [PATCH 02/24] xfs: add an inode item lock Dave Chinner
2020-05-22  6:45   ` Amir Goldstein
2020-05-22 21:24   ` Darrick J. Wong
2020-05-23  8:45   ` Christoph Hellwig
2020-05-22  3:50 ` [PATCH 03/24] xfs: mark inode buffers in cache Dave Chinner
2020-05-22  7:45   ` Amir Goldstein
2020-05-22 21:35   ` Darrick J. Wong
2020-05-24 23:41     ` Dave Chinner
2020-05-23  8:48   ` Christoph Hellwig
2020-05-25  0:06     ` Dave Chinner
2020-05-22  3:50 ` [PATCH 04/24] xfs: mark dquot " Dave Chinner
2020-05-22  7:46   ` Amir Goldstein
2020-05-22 21:38   ` Darrick J. Wong
2020-05-22  3:50 ` [PATCH 05/24] xfs: mark log recovery buffers for completion Dave Chinner
2020-05-22  7:41   ` Amir Goldstein
2020-05-24 23:54     ` Dave Chinner
2020-05-22 21:41   ` Darrick J. Wong
2020-05-22  3:50 ` [PATCH 06/24] xfs: call xfs_buf_iodone directly Dave Chinner
2020-05-22  7:56   ` Amir Goldstein
2020-05-22 21:53   ` Darrick J. Wong
2020-05-22  3:50 ` [PATCH 07/24] xfs: clean up whacky buffer log item list reinit Dave Chinner
2020-05-22 22:01   ` Darrick J. Wong
2020-05-23  8:50   ` Christoph Hellwig
2020-05-22  3:50 ` [PATCH 08/24] xfs: fold xfs_istale_done into xfs_iflush_done Dave Chinner
2020-05-22 22:10   ` Darrick J. Wong
2020-05-23  9:12   ` Christoph Hellwig
2020-05-22  3:50 ` [PATCH 09/24] xfs: use direct calls for dquot IO completion Dave Chinner
2020-05-22 22:13   ` Darrick J. Wong
2020-05-23  9:16   ` Christoph Hellwig
2020-05-22  3:50 ` [PATCH 10/24] xfs: clean up the buffer iodone callback functions Dave Chinner
2020-05-22 22:26   ` Darrick J. Wong
2020-05-25  0:37     ` Dave Chinner
2020-05-23  9:19   ` Christoph Hellwig
2020-05-22  3:50 ` [PATCH 11/24] xfs: get rid of log item callbacks Dave Chinner
2020-05-22 22:27   ` Darrick J. Wong
2020-05-23  9:19   ` Christoph Hellwig
2020-05-22  3:50 ` [PATCH 12/24] xfs: pin inode backing buffer to the inode log item Dave Chinner
2020-05-22 22:39   ` Darrick J. Wong
2020-05-23  9:34   ` Christoph Hellwig
2020-05-23 21:43     ` Dave Chinner
2020-05-24  5:31       ` Christoph Hellwig
2020-05-24 23:13         ` Dave Chinner
2020-05-22  3:50 ` [PATCH 13/24] xfs: make inode reclaim almost non-blocking Dave Chinner
2020-05-22 12:19   ` Amir Goldstein
2020-05-22 22:48   ` Darrick J. Wong
2020-05-23 22:29     ` Dave Chinner
2020-05-22  3:50 ` [PATCH 14/24] xfs: remove IO submission from xfs_reclaim_inode() Dave Chinner
2020-05-22 23:06   ` Darrick J. Wong
2020-05-25  3:49     ` Dave Chinner
2020-05-23  9:40   ` Christoph Hellwig
2020-05-23 22:35     ` Dave Chinner
2020-05-22  3:50 ` [PATCH 15/24] xfs: allow multiple reclaimers per AG Dave Chinner
2020-05-22 23:10   ` Darrick J. Wong
2020-05-23 22:35     ` Dave Chinner
2020-05-22  3:50 ` [PATCH 16/24] xfs: don't block inode reclaim on the ILOCK Dave Chinner
2020-05-22 23:11   ` Darrick J. Wong
2020-05-22  3:50 ` [PATCH 17/24] xfs: remove SYNC_TRYLOCK from inode reclaim Dave Chinner
2020-05-22 23:14   ` Darrick J. Wong
2020-05-23 22:42     ` Dave Chinner
2020-05-22  3:50 ` [PATCH 18/24] xfs: clean up inode reclaim comments Dave Chinner
2020-05-22 23:17   ` Darrick J. Wong
2020-05-22  3:50 ` [PATCH 19/24] xfs: attach inodes to the cluster buffer when dirtied Dave Chinner
2020-05-22 23:48   ` Darrick J. Wong
2020-05-23 22:59     ` Dave Chinner
2020-05-22  3:50 ` Dave Chinner [this message]
2020-05-22 23:54   ` [PATCH 20/24] xfs: xfs_iflush() is no longer necessary Darrick J. Wong
2020-05-22  3:50 ` [PATCH 21/24] xfs: rename xfs_iflush_int() Dave Chinner
2020-05-22 12:33   ` Amir Goldstein
2020-05-22 23:57   ` Darrick J. Wong
2020-05-22  3:50 ` [PATCH 22/24] xfs: rework xfs_iflush_cluster() dirty inode iteration Dave Chinner
2020-05-23  0:13   ` Darrick J. Wong
2020-05-23 23:14     ` Dave Chinner
2020-05-23 11:31   ` Christoph Hellwig
2020-05-23 23:23     ` Dave Chinner
2020-05-24  5:32       ` Christoph Hellwig
2020-05-23 11:39   ` Christoph Hellwig
2020-05-22  3:50 ` [PATCH 23/24] xfs: factor xfs_iflush_done Dave Chinner
2020-05-23  0:20   ` Darrick J. Wong
2020-05-23 11:35   ` Christoph Hellwig
2020-05-22  3:50 ` [PATCH 24/24] xfs: remove xfs_inobp_check() Dave Chinner
2020-05-23  0:16   ` Darrick J. Wong
2020-05-23 11:36   ` Christoph Hellwig
2020-05-22  4:04 ` [PATCH 00/24] xfs: rework inode flushing to make inode reclaim fully asynchronous Dave Chinner
2020-05-23 16:18   ` Darrick J. Wong
2020-05-23 21:22     ` Dave Chinner
2020-05-22  6:18 ` Amir Goldstein
2020-05-22 12:01   ` Amir Goldstein

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