From 745b3f76d1c889d738a1c4537a3c491bc1ecac4d Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 17 Jul 2018 16:51:51 -0700 Subject: xfs: maintain a sequence count for inode fork manipulations Add a simple 32-bit unsigned integer as the sequence count for modifications to the extent list in the inode fork. This will be used to optimize away extent list lookups in the writeback code. Signed-off-by: Christoph Hellwig Reviewed-by: Carlos Maiolino Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/libxfs/xfs_iext_tree.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'fs/xfs/libxfs/xfs_iext_tree.c') diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c index b80c63faace2..8a7aea041ee1 100644 --- a/fs/xfs/libxfs/xfs_iext_tree.c +++ b/fs/xfs/libxfs/xfs_iext_tree.c @@ -624,6 +624,8 @@ xfs_iext_insert( struct xfs_iext_leaf *new = NULL; int nr_entries, i; + ifp->if_seq++; + if (ifp->if_height == 0) xfs_iext_alloc_root(ifp, cur); else if (ifp->if_height == 1) @@ -864,6 +866,8 @@ xfs_iext_remove( ASSERT(ifp->if_u1.if_root != NULL); ASSERT(xfs_iext_valid(ifp, cur)); + ifp->if_seq++; + nr_entries = xfs_iext_leaf_nr_entries(ifp, leaf, cur->pos) - 1; for (i = cur->pos; i < nr_entries; i++) leaf->recs[i] = leaf->recs[i + 1]; @@ -970,6 +974,8 @@ xfs_iext_update_extent( { struct xfs_ifork *ifp = xfs_iext_state_to_fork(ip, state); + ifp->if_seq++; + if (cur->pos == 0) { struct xfs_bmbt_irec old; -- cgit v1.2.3 From 2ba090d521c5e09f32316c179d25bb6f699d3568 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 7 Aug 2018 10:57:12 -0700 Subject: xfs: use WRITE_ONCE to update if_seq This adds ordering of the updates and makes sure we always see the if_seq update before the extent tree is modified. Signed-off-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/libxfs/xfs_iext_tree.c | 20 +++++++++++++++++--- fs/xfs/xfs_aops.c | 4 ++-- fs/xfs/xfs_iomap.c | 3 ++- 3 files changed, 21 insertions(+), 6 deletions(-) (limited to 'fs/xfs/libxfs/xfs_iext_tree.c') diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c index 8a7aea041ee1..771dd072015d 100644 --- a/fs/xfs/libxfs/xfs_iext_tree.c +++ b/fs/xfs/libxfs/xfs_iext_tree.c @@ -14,6 +14,7 @@ #include "xfs_inode_fork.h" #include "xfs_trans_resv.h" #include "xfs_mount.h" +#include "xfs_bmap.h" #include "xfs_trace.h" /* @@ -612,6 +613,19 @@ xfs_iext_realloc_root( cur->leaf = new; } +/* + * Increment the sequence counter if we are on a COW fork. This allows + * the writeback code to skip looking for a COW extent if the COW fork + * hasn't changed. We use WRITE_ONCE here to ensure the update to the + * sequence counter is seen before the modifications to the extent + * tree itself take effect. + */ +static inline void xfs_iext_inc_seq(struct xfs_ifork *ifp, int state) +{ + if (state & BMAP_COWFORK) + WRITE_ONCE(ifp->if_seq, READ_ONCE(ifp->if_seq) + 1); +} + void xfs_iext_insert( struct xfs_inode *ip, @@ -624,7 +638,7 @@ xfs_iext_insert( struct xfs_iext_leaf *new = NULL; int nr_entries, i; - ifp->if_seq++; + xfs_iext_inc_seq(ifp, state); if (ifp->if_height == 0) xfs_iext_alloc_root(ifp, cur); @@ -866,7 +880,7 @@ xfs_iext_remove( ASSERT(ifp->if_u1.if_root != NULL); ASSERT(xfs_iext_valid(ifp, cur)); - ifp->if_seq++; + xfs_iext_inc_seq(ifp, state); nr_entries = xfs_iext_leaf_nr_entries(ifp, leaf, cur->pos) - 1; for (i = cur->pos; i < nr_entries; i++) @@ -974,7 +988,7 @@ xfs_iext_update_extent( { struct xfs_ifork *ifp = xfs_iext_state_to_fork(ip, state); - ifp->if_seq++; + xfs_iext_inc_seq(ifp, state); if (cur->pos == 0) { struct xfs_bmbt_irec old; diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index 235b4ddcd324..49f5f5896a43 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -351,7 +351,7 @@ xfs_map_blocks( if (imap_valid && (!xfs_inode_has_cow_data(ip) || wpc->io_type == XFS_IO_COW || - wpc->cow_seq == ip->i_cowfp->if_seq)) + wpc->cow_seq == READ_ONCE(ip->i_cowfp->if_seq))) return 0; if (XFS_FORCED_SHUTDOWN(mp)) @@ -380,7 +380,7 @@ xfs_map_blocks( xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &imap)) cow_fsb = imap.br_startoff; if (cow_fsb != NULLFILEOFF && cow_fsb <= offset_fsb) { - wpc->cow_seq = ip->i_cowfp->if_seq; + wpc->cow_seq = READ_ONCE(ip->i_cowfp->if_seq); xfs_iunlock(ip, XFS_ILOCK_SHARED); /* * Truncate can race with writeback since writeback doesn't diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 3282575e2df4..6320aca39f39 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -655,6 +655,7 @@ xfs_iomap_write_allocate( unsigned int *cow_seq) { xfs_mount_t *mp = ip->i_mount; + struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork); xfs_fileoff_t offset_fsb, last_block; xfs_fileoff_t end_fsb, map_start_fsb; xfs_filblks_t count_fsb; @@ -768,7 +769,7 @@ xfs_iomap_write_allocate( goto error0; if (whichfork == XFS_COW_FORK) - *cow_seq = XFS_IFORK_PTR(ip, whichfork)->if_seq; + *cow_seq = READ_ONCE(ifp->if_seq); xfs_iunlock(ip, XFS_ILOCK_EXCL); } -- cgit v1.2.3