From 90c60e16401248a4900f3f9387f563d0178dcf34 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Mon, 29 Jun 2020 14:49:19 -0700 Subject: [PATCH] xfs: xfs_iflush() is no longer necessary 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 Reviewed-by: Darrick J. Wong Reviewed-by: Brian Foster Signed-off-by: Darrick J. Wong --- fs/xfs/xfs_inode.c | 107 ++++++---------------------------------- fs/xfs/xfs_inode.h | 2 +- fs/xfs/xfs_inode_item.c | 51 +++++++------------ 3 files changed, 33 insertions(+), 127 deletions(-) diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c index c4586ac3656a..4a9539048639 100644 --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -3450,7 +3450,18 @@ 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) @@ -3485,8 +3496,6 @@ 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 @@ -3577,99 +3586,11 @@ 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; } @@ -3687,7 +3608,7 @@ xfs_iflush_int( 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)); - 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 1534386b430c..c482e7306fe0 100644 --- a/fs/xfs/xfs_inode.h +++ b/fs/xfs/xfs_inode.h @@ -426,7 +426,7 @@ 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 697248b7eb2b..e8eda2ac25fb 100644 --- a/fs/xfs/xfs_inode_item.c +++ b/fs/xfs/xfs_inode_item.c @@ -485,53 +485,38 @@ xfs_inode_item_push( uint rval = XFS_ITEM_SUCCESS; int error; - if (xfs_ipincount(ip) > 0) + ASSERT(iip->ili_item.li_buf); + + if (xfs_ipincount(ip) > 0 || xfs_buf_ispinned(bp) || + (ip->i_flags & XFS_ISTALE)) return XFS_ITEM_PINNED; - if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED)) - return XFS_ITEM_LOCKED; + /* If the inode is already flush locked, we're already flushing. */ + if (xfs_isiflocked(ip)) + return XFS_ITEM_FLUSHING; - /* - * 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 (!xfs_buf_trylock(bp)) + return XFS_ITEM_LOCKED; - /* - * Stale inode items should force out the iclog. - */ - if (ip->i_flags & XFS_ISTALE) { - rval = XFS_ITEM_PINNED; - goto out_unlock; - } + spin_unlock(&lip->li_ailp->ail_lock); /* - * 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. + * We need to hold a reference for flushing the cluster buffer as it may + * fail the buffer without IO submission. In which case, we better get a + * reference for that completion because otherwise we don't get a + * reference for IO until we queue the buffer for delwri submission. */ - if (!xfs_iflock_nowait(ip)) { - rval = XFS_ITEM_FLUSHING; - goto out_unlock; - } - - ASSERT(iip->ili_fields != 0 || XFS_FORCED_SHUTDOWN(ip->i_mount)); - spin_unlock(&lip->li_ailp->ail_lock); - - error = xfs_iflush(ip, &bp); + xfs_buf_hold(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) + } else { rval = XFS_ITEM_LOCKED; + } spin_lock(&lip->li_ailp->ail_lock); -out_unlock: - xfs_iunlock(ip, XFS_ILOCK_SHARED); return rval; } -- GitLab