From 4d53dddbec671bcb64a936a3d2b7bf1ce2252ed0 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Fri, 17 Feb 2017 15:27:44 +0100 Subject: [PATCH] btrfs: document existence of extent_io ops callbacks Some of the callbacks defined in btree_extent_io_ops and btrfs_extent_io_ops do always exist so we don't need to check the existence before each call. This patch just reorders the definition and documents which are mandatory/optional. Signed-off-by: David Sterba --- fs/btrfs/disk-io.c | 7 +++++-- fs/btrfs/extent_io.h | 23 ++++++++++++++++------- fs/btrfs/inode.c | 7 +++++-- 3 files changed, 26 insertions(+), 11 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 67d663ab658a..60d4f1b210d7 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -4653,9 +4653,12 @@ static int btrfs_cleanup_transaction(struct btrfs_fs_info *fs_info) } static const struct extent_io_ops btree_extent_io_ops = { - .readpage_end_io_hook = btree_readpage_end_io_hook, - .readpage_io_failed_hook = btree_io_failed_hook, + /* mandatory callbacks */ .submit_bio_hook = btree_submit_bio_hook, + .readpage_end_io_hook = btree_readpage_end_io_hook, /* note we're sharing with inode.c for the merge bio hook */ .merge_bio_hook = btrfs_merge_bio_hook, + + /* optional callbacks */ + .readpage_io_failed_hook = btree_io_failed_hook, }; diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index 78bb4d76127b..1f8478dc9f8e 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -92,18 +92,27 @@ typedef int (extent_submit_bio_hook_t)(struct inode *inode, struct bio *bio, int mirror_num, unsigned long bio_flags, u64 bio_offset); struct extent_io_ops { - int (*fill_delalloc)(struct inode *inode, struct page *locked_page, - u64 start, u64 end, int *page_started, - unsigned long *nr_written); - int (*writepage_start_hook)(struct page *page, u64 start, u64 end); + /* + * The following callbacks must be allways defined, the function + * pointer will be called unconditionally. + */ extent_submit_bio_hook_t *submit_bio_hook; + int (*readpage_end_io_hook)(struct btrfs_io_bio *io_bio, u64 phy_offset, + struct page *page, u64 start, u64 end, + int mirror); int (*merge_bio_hook)(struct page *page, unsigned long offset, size_t size, struct bio *bio, unsigned long bio_flags); + + /* + * Optional hooks, called if the pointer is not NULL + */ + int (*fill_delalloc)(struct inode *inode, struct page *locked_page, + u64 start, u64 end, int *page_started, + unsigned long *nr_written); int (*readpage_io_failed_hook)(struct page *page, int failed_mirror); - int (*readpage_end_io_hook)(struct btrfs_io_bio *io_bio, u64 phy_offset, - struct page *page, u64 start, u64 end, - int mirror); + + int (*writepage_start_hook)(struct page *page, u64 start, u64 end); void (*writepage_end_io_hook)(struct page *page, u64 start, u64 end, struct extent_state *state, int uptodate); void (*set_bit_hook)(struct inode *inode, struct extent_state *state, diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index b904c74f31fd..3b327c8cfb16 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -10547,10 +10547,13 @@ static const struct file_operations btrfs_dir_file_operations = { }; static const struct extent_io_ops btrfs_extent_io_ops = { - .fill_delalloc = run_delalloc_range, + /* mandatory callbacks */ .submit_bio_hook = btrfs_submit_bio_hook, - .merge_bio_hook = btrfs_merge_bio_hook, .readpage_end_io_hook = btrfs_readpage_end_io_hook, + .merge_bio_hook = btrfs_merge_bio_hook, + + /* optional callbacks */ + .fill_delalloc = run_delalloc_range, .writepage_end_io_hook = btrfs_writepage_end_io_hook, .writepage_start_hook = btrfs_writepage_start_hook, .set_bit_hook = btrfs_set_bit_hook, -- 2.20.1