From 52b029f42751d0aea2d9c05a584438f4f0dfc123 Mon Sep 17 00:00:00 2001 From: Ethan Lien Date: Fri, 19 Aug 2022 10:44:08 +0800 Subject: [PATCH] btrfs: remove unnecessary EXTENT_UPTODATE state in buffered I/O path After we copied data to page cache in buffered I/O, we 1. Insert a EXTENT_UPTODATE state into inode's io_tree, by endio_readpage_release_extent(), set_extent_delalloc() or set_extent_defrag(). 2. Set page uptodate before we unlock the page. But the only place we check io_tree's EXTENT_UPTODATE state is in btrfs_do_readpage(). We know we enter btrfs_do_readpage() only when we have a non-uptodate page, so it is unnecessary to set EXTENT_UPTODATE. For example, when performing a buffered random read: fio --rw=randread --ioengine=libaio --direct=0 --numjobs=4 \ --filesize=32G --size=4G --bs=4k --name=job \ --filename=/mnt/file --name=job Then check how many extent_state in io_tree: cat /proc/slabinfo | grep btrfs_extent_state | awk '{print $2}' w/o this patch, we got 640567 btrfs_extent_state. w/ this patch, we got 204 btrfs_extent_state. Maintaining such a big tree brings overhead since every I/O needs to insert EXTENT_LOCKED, insert EXTENT_UPTODATE, then remove EXTENT_LOCKED. And in every insert or remove, we need to lock io_tree, do tree search, alloc or dealloc extent states. By removing unnecessary EXTENT_UPTODATE, we keep io_tree in a minimal size and reduce overhead when performing buffered I/O. Reviewed-by: Filipe Manana Reviewed-by: Robbie Ko Signed-off-by: Ethan Lien Signed-off-by: David Sterba --- fs/btrfs/extent-io-tree.h | 4 ++-- fs/btrfs/extent_io.c | 18 +----------------- fs/btrfs/inode.c | 3 --- 3 files changed, 3 insertions(+), 22 deletions(-) diff --git a/fs/btrfs/extent-io-tree.h b/fs/btrfs/extent-io-tree.h index c3eb52d..53ae849 100644 --- a/fs/btrfs/extent-io-tree.h +++ b/fs/btrfs/extent-io-tree.h @@ -211,7 +211,7 @@ static inline int set_extent_delalloc(struct extent_io_tree *tree, u64 start, struct extent_state **cached_state) { return set_extent_bit(tree, start, end, - EXTENT_DELALLOC | EXTENT_UPTODATE | extra_bits, + EXTENT_DELALLOC | extra_bits, 0, NULL, cached_state, GFP_NOFS, NULL); } @@ -219,7 +219,7 @@ static inline int set_extent_defrag(struct extent_io_tree *tree, u64 start, u64 end, struct extent_state **cached_state) { return set_extent_bit(tree, start, end, - EXTENT_DELALLOC | EXTENT_UPTODATE | EXTENT_DEFRAG, + EXTENT_DELALLOC | EXTENT_DEFRAG, 0, NULL, cached_state, GFP_NOFS, NULL); } diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 63decf3..f57a3e9 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2924,9 +2924,6 @@ static void endio_readpage_release_extent(struct processed_extent *processed, * Now we don't have range contiguous to the processed range, release * the processed range now. */ - if (processed->uptodate && tree->track_uptodate) - set_extent_uptodate(tree, processed->start, processed->end, - &cached, GFP_ATOMIC); unlock_extent_cached_atomic(tree, processed->start, processed->end, &cached); @@ -3613,7 +3610,6 @@ static int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, u64 extent_offset; u64 last_byte = i_size_read(inode); u64 block_start; - u64 cur_end; struct extent_map *em; int ret = 0; size_t pg_offset = 0; @@ -3672,7 +3668,6 @@ static int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, this_bio_flag = em->compress_type; iosize = min(extent_map_end(em) - cur, end - cur + 1); - cur_end = min(extent_map_end(em) - 1, end); iosize = ALIGN(iosize, blocksize); if (this_bio_flag != BTRFS_COMPRESS_NONE) disk_bytenr = em->block_start; @@ -3743,20 +3738,9 @@ static int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, continue; } /* the get_extent function already copied into the page */ - if (test_range_bit(tree, cur, cur_end, - EXTENT_UPTODATE, 1, NULL)) { - unlock_extent(tree, cur, cur + iosize - 1); - end_page_read(page, true, cur, iosize); - cur = cur + iosize; - pg_offset += iosize; - continue; - } - /* we have an inline extent but it didn't get marked up - * to date. Error out - */ if (block_start == EXTENT_MAP_INLINE) { unlock_extent(tree, cur, cur + iosize - 1); - end_page_read(page, false, cur, iosize); + end_page_read(page, true, cur, iosize); cur = cur + iosize; pg_offset += iosize; continue; diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index b04ce7a..0a77705 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -6868,7 +6868,6 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode, struct btrfs_key found_key; struct extent_map *em = NULL; struct extent_map_tree *em_tree = &inode->extent_tree; - struct extent_io_tree *io_tree = &inode->io_tree; read_lock(&em_tree->lock); em = lookup_extent_mapping(em_tree, start, len); @@ -7031,8 +7030,6 @@ next: } flush_dcache_page(page); } - set_extent_uptodate(io_tree, em->start, - extent_map_end(em) - 1, NULL, GFP_NOFS); goto insert; } not_found: -- 2.7.4