From 777df5afdb26c71634edd60582be620ff94e87a0 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Sat, 6 Feb 2010 12:37:26 +1100 Subject: xfs: Make inode reclaim states explicit A.K.A.: don't rely on xfs_iflush() return value in reclaim We have gradually been moving checks out of the reclaim code because they are duplicated in xfs_iflush(). We've had a history of problems in this area, and many of them stem from the overloading of the return values from xfs_iflush() and interaction with inode flush locking to determine if the inode is safe to reclaim. With the desire to move to delayed write flushing of inodes and non-blocking inode tree reclaim walks, the overloading of the return value of xfs_iflush makes it very difficult to determine the correct thing to do next. This patch explicitly re-adds the checks to the inode reclaim code, removing the reliance on the return value of xfs_iflush() to determine what to do next. It also means that we can clearly document all the inode states that reclaim must handle and hence we can easily see that we handled all the necessary cases. This also removes the need for the xfs_inode_clean() check in xfs_iflush() as all callers now check this first (safely). Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_inode.h | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/xfs/xfs_inode.h') diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h index ec1f28c4fc4f..8b618ea4d692 100644 --- a/fs/xfs/xfs_inode.h +++ b/fs/xfs/xfs_inode.h @@ -483,6 +483,7 @@ int xfs_iunlink(struct xfs_trans *, xfs_inode_t *); void xfs_iext_realloc(xfs_inode_t *, int, int); void xfs_ipin(xfs_inode_t *); void xfs_iunpin(xfs_inode_t *); +void xfs_iunpin_wait(xfs_inode_t *); int xfs_iflush(xfs_inode_t *, uint); void xfs_ichgtime(xfs_inode_t *, int); void xfs_lock_inodes(xfs_inode_t **, int, uint); -- cgit v1.2.3 From c854363e80b49dd04a4de18ebc379eb8c8806674 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Sat, 6 Feb 2010 12:39:36 +1100 Subject: 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 Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_inode.h | 10 ---------- 1 file changed, 10 deletions(-) (limited to 'fs/xfs/xfs_inode.h') diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h index 8b618ea4d692..6c912b027596 100644 --- a/fs/xfs/xfs_inode.h +++ b/fs/xfs/xfs_inode.h @@ -419,16 +419,6 @@ static inline void xfs_ifunlock(xfs_inode_t *ip) #define XFS_IOLOCK_DEP(flags) (((flags) & XFS_IOLOCK_DEP_MASK) >> XFS_IOLOCK_SHIFT) #define XFS_ILOCK_DEP(flags) (((flags) & XFS_ILOCK_DEP_MASK) >> XFS_ILOCK_SHIFT) -/* - * Flags for xfs_iflush() - */ -#define XFS_IFLUSH_DELWRI_ELSE_SYNC 1 -#define XFS_IFLUSH_DELWRI_ELSE_ASYNC 2 -#define XFS_IFLUSH_SYNC 3 -#define XFS_IFLUSH_ASYNC 4 -#define XFS_IFLUSH_DELWRI 5 -#define XFS_IFLUSH_ASYNC_NOBLOCK 6 - /* * Flags for xfs_itruncate_start(). */ -- cgit v1.2.3