From 19b6caf4acbf065dc96b47741d99f1b87243c468 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Mon, 25 Jul 2011 06:50:50 -0400 Subject: [PATCH] Btrfs: reduce extent_state lock contention for metadata For metadata buffers that don't straddle pages (all of them), btrfs can safely use the page uptodate bits and extent_buffer uptodate bit instead of needing to use the extent_state tree. This greatly reduces contention on the state tree lock. Signed-off-by: Chris Mason --- fs/btrfs/extent_io.c | 55 +++++++++++++++++++++++++++++++++----------- 1 file changed, 41 insertions(+), 14 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 5392c3b12fc1..7b60f621e761 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3268,6 +3268,22 @@ int set_extent_buffer_dirty(struct extent_io_tree *tree, return was_dirty; } +static int __eb_straddles_pages(u64 start, u64 len) +{ + if (len < PAGE_CACHE_SIZE) + return 1; + if (start & (PAGE_CACHE_SIZE - 1)) + return 1; + if ((start + len) & (PAGE_CACHE_SIZE - 1)) + return 1; + return 0; +} + +static int eb_straddles_pages(struct extent_buffer *eb) +{ + return __eb_straddles_pages(eb->start, eb->len); +} + int clear_extent_buffer_uptodate(struct extent_io_tree *tree, struct extent_buffer *eb, struct extent_state **cached_state) @@ -3279,8 +3295,10 @@ int clear_extent_buffer_uptodate(struct extent_io_tree *tree, num_pages = num_extent_pages(eb->start, eb->len); clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); - clear_extent_uptodate(tree, eb->start, eb->start + eb->len - 1, - cached_state, GFP_NOFS); + if (eb_straddles_pages(eb)) { + clear_extent_uptodate(tree, eb->start, eb->start + eb->len - 1, + cached_state, GFP_NOFS); + } for (i = 0; i < num_pages; i++) { page = extent_buffer_page(eb, i); if (page) @@ -3298,8 +3316,10 @@ int set_extent_buffer_uptodate(struct extent_io_tree *tree, num_pages = num_extent_pages(eb->start, eb->len); - set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1, - NULL, GFP_NOFS); + if (eb_straddles_pages(eb)) { + set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1, + NULL, GFP_NOFS); + } for (i = 0; i < num_pages; i++) { page = extent_buffer_page(eb, i); if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) || @@ -3322,9 +3342,12 @@ int extent_range_uptodate(struct extent_io_tree *tree, int uptodate; unsigned long index; - ret = test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL); - if (ret) - return 1; + if (__eb_straddles_pages(start, end - start + 1)) { + ret = test_range_bit(tree, start, end, + EXTENT_UPTODATE, 1, NULL); + if (ret) + return 1; + } while (start <= end) { index = start >> PAGE_CACHE_SHIFT; page = find_get_page(tree->mapping, index); @@ -3352,10 +3375,12 @@ int extent_buffer_uptodate(struct extent_io_tree *tree, if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) return 1; - ret = test_range_bit(tree, eb->start, eb->start + eb->len - 1, - EXTENT_UPTODATE, 1, cached_state); - if (ret) - return ret; + if (eb_straddles_pages(eb)) { + ret = test_range_bit(tree, eb->start, eb->start + eb->len - 1, + EXTENT_UPTODATE, 1, cached_state); + if (ret) + return ret; + } num_pages = num_extent_pages(eb->start, eb->len); for (i = 0; i < num_pages; i++) { @@ -3388,9 +3413,11 @@ int read_extent_buffer_pages(struct extent_io_tree *tree, if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) return 0; - if (test_range_bit(tree, eb->start, eb->start + eb->len - 1, - EXTENT_UPTODATE, 1, NULL)) { - return 0; + if (eb_straddles_pages(eb)) { + if (test_range_bit(tree, eb->start, eb->start + eb->len - 1, + EXTENT_UPTODATE, 1, NULL)) { + return 0; + } } if (start) { -- 2.20.1