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authorDave Chinner <david@fromorbit.com>2010-02-06 12:39:36 +1100
committerDave Chinner <david@fromorbit.com>2010-02-06 12:39:36 +1100
commitc854363e80b49dd04a4de18ebc379eb8c8806674 (patch)
tree8c8d0dec26d961631a3cd8b6c402b5d1444336e5 /fs/xfs/xfs_inode.c
parent777df5afdb26c71634edd60582be620ff94e87a0 (diff)
downloadop-kernel-dev-c854363e80b49dd04a4de18ebc379eb8c8806674.zip
op-kernel-dev-c854363e80b49dd04a4de18ebc379eb8c8806674.tar.gz
xfs: Use delayed write for inodes rather than async V2
We currently do background inode flush asynchronously, resulting in inodes being written in whatever order the background writeback issues them. Not only that, there are also blocking and non-blocking asynchronous inode flushes, depending on where the flush comes from. This patch completely removes asynchronous inode writeback. It removes all the strange writeback modes and replaces them with either a synchronous flush or a non-blocking delayed write flush. That is, inode flushes will only issue IO directly if they are synchronous, and background flushing may do nothing if the operation would block (e.g. on a pinned inode or buffer lock). Delayed write flushes will now result in the inode buffer sitting in the delwri queue of the buffer cache to be flushed by either an AIL push or by the xfsbufd timing out the buffer. This will allow accumulation of dirty inode buffers in memory and allow optimisation of inode cluster writeback at the xfsbufd level where we have much greater queue depths than the block layer elevators. We will also get adjacent inode cluster buffer IO merging for free when a later patch in the series allows sorting of the delayed write buffers before dispatch. This effectively means that any inode that is written back by background writeback will be seen as flush locked during AIL pushing, and will result in the buffers being pushed from there. This writeback path is currently non-optimal, but the next patch in the series will fix that problem. A side effect of this delayed write mechanism is that background inode reclaim will no longer directly flush inodes, nor can it wait on the flush lock. The result is that inode reclaim must leave the inode in the reclaimable state until it is clean. Hence attempts to reclaim a dirty inode in the background will simply skip the inode until it is clean and this allows other mechanisms (i.e. xfsbufd) to do more optimal writeback of the dirty buffers. As a result, the inode reclaim code has been rewritten so that it no longer relies on the ambiguous return values of xfs_iflush() to determine whether it is safe to reclaim an inode. Portions of this patch are derived from patches by Christoph Hellwig. Version 2: - cleanup reclaim code as suggested by Christoph - log background reclaim inode flush errors - just pass sync flags to xfs_iflush Signed-off-by: Dave Chinner <david@fromorbit.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs/xfs/xfs_inode.c')
-rw-r--r--fs/xfs/xfs_inode.c75
1 files changed, 5 insertions, 70 deletions
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 8d0666d..fa31360 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -2835,8 +2835,6 @@ xfs_iflush(
xfs_dinode_t *dip;
xfs_mount_t *mp;
int error;
- int noblock = (flags == XFS_IFLUSH_ASYNC_NOBLOCK);
- enum { INT_DELWRI = (1 << 0), INT_ASYNC = (1 << 1) };
XFS_STATS_INC(xs_iflush_count);
@@ -2859,7 +2857,7 @@ xfs_iflush(
* in the same cluster are dirty, they will probably write the inode
* out for us if they occur after the log force completes.
*/
- if (noblock && xfs_ipincount(ip)) {
+ if (!(flags & SYNC_WAIT) && xfs_ipincount(ip)) {
xfs_iunpin_nowait(ip);
xfs_ifunlock(ip);
return EAGAIN;
@@ -2893,60 +2891,10 @@ xfs_iflush(
}
/*
- * Decide how buffer will be flushed out. This is done before
- * the call to xfs_iflush_int because this field is zeroed by it.
- */
- if (iip != NULL && iip->ili_format.ilf_fields != 0) {
- /*
- * Flush out the inode buffer according to the directions
- * of the caller. In the cases where the caller has given
- * us a choice choose the non-delwri case. This is because
- * the inode is in the AIL and we need to get it out soon.
- */
- switch (flags) {
- case XFS_IFLUSH_SYNC:
- case XFS_IFLUSH_DELWRI_ELSE_SYNC:
- flags = 0;
- break;
- case XFS_IFLUSH_ASYNC_NOBLOCK:
- case XFS_IFLUSH_ASYNC:
- case XFS_IFLUSH_DELWRI_ELSE_ASYNC:
- flags = INT_ASYNC;
- break;
- case XFS_IFLUSH_DELWRI:
- flags = INT_DELWRI;
- break;
- default:
- ASSERT(0);
- flags = 0;
- break;
- }
- } else {
- switch (flags) {
- case XFS_IFLUSH_DELWRI_ELSE_SYNC:
- case XFS_IFLUSH_DELWRI_ELSE_ASYNC:
- case XFS_IFLUSH_DELWRI:
- flags = INT_DELWRI;
- break;
- case XFS_IFLUSH_ASYNC_NOBLOCK:
- case XFS_IFLUSH_ASYNC:
- flags = INT_ASYNC;
- break;
- case XFS_IFLUSH_SYNC:
- flags = 0;
- break;
- default:
- ASSERT(0);
- flags = 0;
- break;
- }
- }
-
- /*
* Get the buffer containing the on-disk inode.
*/
error = xfs_itobp(mp, NULL, ip, &dip, &bp,
- noblock ? XBF_TRYLOCK : XBF_LOCK);
+ (flags & SYNC_WAIT) ? XBF_LOCK : XBF_TRYLOCK);
if (error || !bp) {
xfs_ifunlock(ip);
return error;
@@ -2974,13 +2922,10 @@ xfs_iflush(
if (error)
goto cluster_corrupt_out;
- if (flags & INT_DELWRI) {
- xfs_bdwrite(mp, bp);
- } else if (flags & INT_ASYNC) {
- error = xfs_bawrite(mp, bp);
- } else {
+ if (flags & SYNC_WAIT)
error = xfs_bwrite(mp, bp);
- }
+ else
+ xfs_bdwrite(mp, bp);
return error;
corrupt_out:
@@ -3015,16 +2960,6 @@ xfs_iflush_int(
iip = ip->i_itemp;
mp = ip->i_mount;
-
- /*
- * If the inode isn't dirty, then just release the inode
- * flush lock and do nothing.
- */
- if (xfs_inode_clean(ip)) {
- xfs_ifunlock(ip);
- return 0;
- }
-
/* set *dip = inode's place in the buffer */
dip = (xfs_dinode_t *)xfs_buf_offset(bp, ip->i_imap.im_boffset);
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