From 18f62b86c4ea943256f8962ecd0cb013c97b4e0f Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 24 Jul 2023 07:22:39 -0700 Subject: [PATCH] btrfs: cleanup the COW fallback logic in run_delalloc_nocow Use the block group pointer used to track the outstanding NOCOW writes as a boolean to remove the duplicate nocow variable, and keep it contained in the main loop to simplify the logic. Reviewed-by: Boris Burkov Signed-off-by: Christoph Hellwig Signed-off-by: David Sterba --- fs/btrfs/inode.c | 47 ++++++++++++++++++++++------------------------- 1 file changed, 22 insertions(+), 25 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 0d973a9..1fb1e4a 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1974,8 +1974,6 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode, int ret; bool check_prev = true; u64 ino = btrfs_ino(inode); - struct btrfs_block_group *bg; - bool nocow = false; struct can_nocow_file_extent_args nocow_args = { 0 }; path = btrfs_alloc_path(); @@ -1993,6 +1991,7 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode, nocow_args.writeback_path = true; while (1) { + struct btrfs_block_group *nocow_bg = NULL; struct btrfs_ordered_extent *ordered; struct btrfs_key found_key; struct btrfs_file_extent_item *fi; @@ -2003,8 +2002,6 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode, int extent_type; bool is_prealloc; - nocow = false; - ret = btrfs_lookup_file_extent(NULL, root, path, ino, cur_offset, 0); if (ret < 0) @@ -2063,7 +2060,7 @@ next_slot: if (found_key.offset > cur_offset) { extent_end = found_key.offset; extent_type = 0; - goto out_check; + goto must_cow; } /* @@ -2096,18 +2093,19 @@ next_slot: if (ret < 0) goto error; if (ret == 0) - goto out_check; + goto must_cow; ret = 0; - bg = btrfs_inc_nocow_writers(fs_info, nocow_args.disk_bytenr); - if (bg) - nocow = true; -out_check: - /* - * If nocow is false then record the beginning of the range - * that needs to be COWed - */ - if (!nocow) { + nocow_bg = btrfs_inc_nocow_writers(fs_info, nocow_args.disk_bytenr); + if (!nocow_bg) { +must_cow: + /* + * If we can't perform NOCOW writeback for the range, + * then record the beginning of the range that needs to + * be COWed. It will be written out before the next + * NOCOW range if we find one, or when exiting this + * loop. + */ if (cow_start == (u64)-1) cow_start = cur_offset; cur_offset = extent_end; @@ -2128,8 +2126,10 @@ out_check: ret = fallback_to_cow(inode, locked_page, cow_start, found_key.offset - 1); cow_start = (u64)-1; - if (ret) + if (ret) { + btrfs_dec_nocow_writers(nocow_bg); goto error; + } } nocow_end = cur_offset + nocow_args.num_bytes - 1; @@ -2146,6 +2146,7 @@ out_check: ram_bytes, BTRFS_COMPRESS_NONE, BTRFS_ORDERED_PREALLOC); if (IS_ERR(em)) { + btrfs_dec_nocow_writers(nocow_bg); ret = PTR_ERR(em); goto error; } @@ -2159,6 +2160,7 @@ out_check: ? (1 << BTRFS_ORDERED_PREALLOC) : (1 << BTRFS_ORDERED_NOCOW), BTRFS_COMPRESS_NONE); + btrfs_dec_nocow_writers(nocow_bg); if (IS_ERR(ordered)) { if (is_prealloc) { btrfs_drop_extent_map_range(inode, cur_offset, @@ -2168,11 +2170,6 @@ out_check: goto error; } - if (nocow) { - btrfs_dec_nocow_writers(bg); - nocow = false; - } - if (btrfs_is_data_reloc_root(root)) /* * Error handled later, as we must prevent @@ -2213,10 +2210,10 @@ out_check: goto error; } -error: - if (nocow) - btrfs_dec_nocow_writers(bg); + btrfs_free_path(path); + return 0; +error: /* * If an error happened while a COW region is outstanding, cur_offset * needs to be reset to cow_start to ensure the COW region is unlocked @@ -2224,7 +2221,7 @@ error: */ if (cow_start != (u64)-1) cur_offset = cow_start; - if (ret && cur_offset < end) + if (cur_offset < end) extent_clear_unlock_delalloc(inode, cur_offset, end, locked_page, EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DEFRAG | -- 2.7.4