From 18fdc67900c5bfd1eeb41cfa50ea6f2eb7266f73 Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Wed, 13 Sep 2017 12:18:22 -0600 Subject: [PATCH] Btrfs: remove bio_flags which indicates a meta block of log-tree Since both committing transaction and writing log-tree are doing plugging on metadata IO, we can unify to use %sync_writers to benefit both cases, instead of checking bio_flags while writing meta blocks of log-tree. We can remove this bio_flags because in order to write dirty blocks, log tree also uses btrfs_write_marked_extents(), inside which we have enabled %sync_writers, therefore, every write goes in a synchronous way, so does checksuming. Please also note that, bio_flags is applied per-context while %sync_writers is applied per-inode, so this might incur some overhead, ie. 1) while log tree is flushing its dirty blocks via btrfs_write_marked_extents(), in which %sync_writers is increased by one. 2) in the meantime, some writeback operations may happen upon btrfs's metadata inode, so these writes go synchronously, too. However, AFAICS, the overhead is not a big one while the win is that we unify the two places that needs synchronous way and remove a special hack/flag. This removes the bio_flags related stuff for writing log-tree. Signed-off-by: Liu Bo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/disk-io.c | 6 ++---- fs/btrfs/extent_io.c | 13 ++----------- fs/btrfs/extent_io.h | 1 - 3 files changed, 4 insertions(+), 16 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 23442747363e..90310d9e647a 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1005,12 +1005,10 @@ static blk_status_t __btree_submit_bio_done(void *private_data, struct bio *bio, return ret; } -static int check_async_write(struct btrfs_inode *bi, unsigned long bio_flags) +static int check_async_write(struct btrfs_inode *bi) { if (atomic_read(&bi->sync_writers)) return 0; - if (bio_flags & EXTENT_BIO_TREE_LOG) - return 0; #ifdef CONFIG_X86 if (static_cpu_has(X86_FEATURE_XMM4_2)) return 0; @@ -1024,7 +1022,7 @@ static blk_status_t btree_submit_bio_hook(void *private_data, struct bio *bio, { struct inode *inode = private_data; struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); - int async = check_async_write(BTRFS_I(inode), bio_flags); + int async = check_async_write(BTRFS_I(inode)); blk_status_t ret; if (bio_op(bio) != REQ_OP_WRITE) { diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 970190cd347e..0dfcef37352b 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -109,7 +109,6 @@ struct extent_page_data { struct bio *bio; struct extent_io_tree *tree; get_extent_t *get_extent; - unsigned long bio_flags; /* tells writepage not to lock the state bits for this range * it still does the unlocking @@ -3715,7 +3714,6 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb, u64 offset = eb->start; u32 nritems; unsigned long i, num_pages; - unsigned long bio_flags = 0; unsigned long start, end; unsigned int write_flags = wbc_to_write_flags(wbc) | REQ_META; int ret = 0; @@ -3723,8 +3721,6 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb, clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags); num_pages = num_extent_pages(eb->start, eb->len); atomic_set(&eb->io_pages, num_pages); - if (btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID) - bio_flags = EXTENT_BIO_TREE_LOG; /* set btree blocks beyond nritems with 0 to avoid stale content. */ nritems = btrfs_header_nritems(eb); @@ -3751,8 +3747,7 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb, p, offset >> 9, PAGE_SIZE, 0, bdev, &epd->bio, end_bio_extent_buffer_writepage, - 0, epd->bio_flags, bio_flags, false); - epd->bio_flags = bio_flags; + 0, 0, 0, false); if (ret) { set_btree_ioerr(p); if (PageWriteback(p)) @@ -3789,7 +3784,6 @@ int btree_write_cache_pages(struct address_space *mapping, .tree = tree, .extent_locked = 0, .sync_io = wbc->sync_mode == WB_SYNC_ALL, - .bio_flags = 0, }; int ret = 0; int done = 0; @@ -4062,7 +4056,7 @@ static void flush_epd_write_bio(struct extent_page_data *epd) if (epd->bio) { int ret; - ret = submit_one_bio(epd->bio, 0, epd->bio_flags); + ret = submit_one_bio(epd->bio, 0, 0); BUG_ON(ret < 0); /* -ENOMEM */ epd->bio = NULL; } @@ -4085,7 +4079,6 @@ int extent_write_full_page(struct extent_io_tree *tree, struct page *page, .get_extent = get_extent, .extent_locked = 0, .sync_io = wbc->sync_mode == WB_SYNC_ALL, - .bio_flags = 0, }; ret = __extent_writepage(page, wbc, &epd); @@ -4110,7 +4103,6 @@ int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode, .get_extent = get_extent, .extent_locked = 1, .sync_io = mode == WB_SYNC_ALL, - .bio_flags = 0, }; struct writeback_control wbc_writepages = { .sync_mode = mode, @@ -4150,7 +4142,6 @@ int extent_writepages(struct extent_io_tree *tree, .get_extent = get_extent, .extent_locked = 0, .sync_io = wbc->sync_mode == WB_SYNC_ALL, - .bio_flags = 0, }; ret = extent_write_cache_pages(mapping, wbc, __extent_writepage, &epd, diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index faffa28ba707..861dacb371c7 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -33,7 +33,6 @@ * type for this bio */ #define EXTENT_BIO_COMPRESSED 1 -#define EXTENT_BIO_TREE_LOG 2 #define EXTENT_BIO_FLAG_SHIFT 16 /* these are bit numbers for test/set bit */ -- 2.30.2