Commit 87a6962f authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: export the expected file extent through can_nocow_extent() 



Currently function can_nocow_extent() only returns members needed for
extent_map.

However since we will soon change the extent_map structure to be more
like btrfs_file_extent_item, we want to expose the expected file extent
caused by the NOCOW write for future usage.

This introduces a new structure, btrfs_file_extent, to be a more
memory access friendly representation of btrfs_file_extent_item.
And use that structure to expose the expected file extent caused by the
NOCOW write.

For now there is no user of the new structure yet.

Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent e8fe524d

fs/btrfs/btrfs_inode.h

+15 −1
Original line number Diff line number Diff line
@@ -514,9 +514,23 @@ int btrfs_check_sector_csum(struct btrfs_fs_info *fs_info, struct page *page, 
			    u32 pgoff, u8 *csum, const u8 * const csum_expected);

bool btrfs_data_csum_ok(struct btrfs_bio *bbio, struct btrfs_device *dev,

			u32 bio_offset, struct bio_vec *bv);



/*

 * This represents details about the target file extent item of a write operation.

 */

struct btrfs_file_extent {

	u64 disk_bytenr;

	u64 disk_num_bytes;

	u64 num_bytes;

	u64 ram_bytes;

	u64 offset;

	u8 compression;

};



noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,

			      u64 *orig_start, u64 *orig_block_len,

			      u64 *ram_bytes, bool nowait, bool strict);

			      u64 *ram_bytes, struct btrfs_file_extent *file_extent,

			      bool nowait, bool strict);



void btrfs_del_delalloc_inode(struct btrfs_inode *inode);

struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry);

fs/btrfs/file.c

+1 −1
Original line number Diff line number Diff line
@@ -1104,7 +1104,7 @@ int btrfs_check_nocow_lock(struct btrfs_inode *inode, loff_t pos, 
						   &cached_state);

	}

	ret = can_nocow_extent(&inode->vfs_inode, lockstart, &num_bytes,

			NULL, NULL, NULL, nowait, false);

			       NULL, NULL, NULL, NULL, nowait, false);

	if (ret <= 0)

		btrfs_drew_write_unlock(&root->snapshot_lock);

	else

fs/btrfs/inode.c

+18 −3
Original line number Diff line number Diff line
@@ -1856,6 +1856,9 @@ struct can_nocow_file_extent_args { 
	u64 extent_offset;

	/* Number of bytes that can be written to in NOCOW mode. */

	u64 num_bytes;



	/* The expected file extent for the NOCOW write. */

	struct btrfs_file_extent file_extent;

};



/*
@@ -1920,6 +1923,12 @@ static int can_nocow_file_extent(struct btrfs_path *path, 


	extent_end = btrfs_file_extent_end(path);



	args->file_extent.disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);

	args->file_extent.disk_num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);

	args->file_extent.ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);

	args->file_extent.offset = btrfs_file_extent_offset(leaf, fi);

	args->file_extent.compression = btrfs_file_extent_compression(leaf, fi);



	/*

	 * The following checks can be expensive, as they need to take other

	 * locks and do btree or rbtree searches, so release the path to avoid
@@ -1954,6 +1963,9 @@ static int can_nocow_file_extent(struct btrfs_path *path, 
	args->disk_bytenr += args->start - key->offset;

	args->num_bytes = min(args->end + 1, extent_end) - args->start;



	args->file_extent.num_bytes = args->num_bytes;

	args->file_extent.offset += args->start - key->offset;



	/*

	 * Force COW if csums exist in the range. This ensures that csums for a

	 * given extent are either valid or do not exist.
@@ -7138,7 +7150,8 @@ static bool btrfs_extent_readonly(struct btrfs_fs_info *fs_info, u64 bytenr) 
 */

noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,

			      u64 *orig_start, u64 *orig_block_len,

			      u64 *ram_bytes, bool nowait, bool strict)

			      u64 *ram_bytes, struct btrfs_file_extent *file_extent,

			      bool nowait, bool strict)

{

	struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);

	struct can_nocow_file_extent_args nocow_args = { 0 };
@@ -7227,6 +7240,8 @@ noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len, 
		*orig_start = key.offset - nocow_args.extent_offset;

	if (orig_block_len)

		*orig_block_len = nocow_args.disk_num_bytes;

	if (file_extent)

		memcpy(file_extent, &nocow_args.file_extent, sizeof(*file_extent));



	*len = nocow_args.num_bytes;

	ret = 1;
@@ -7446,7 +7461,7 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map, 
		block_start = em->block_start + (start - em->start);



		if (can_nocow_extent(inode, start, &len, &orig_start,

				     &orig_block_len, &ram_bytes, false, false) == 1) {

				     &orig_block_len, &ram_bytes, NULL, false, false) == 1) {

			bg = btrfs_inc_nocow_writers(fs_info, block_start);

			if (bg)

				can_nocow = true;
@@ -10640,7 +10655,7 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file, 
		free_extent_map(em);

		em = NULL;



		ret = can_nocow_extent(inode, start, &len, NULL, NULL, NULL, false, true);

		ret = can_nocow_extent(inode, start, &len, NULL, NULL, NULL, NULL, false, true);

		if (ret < 0) {

			goto out;

		} else if (ret) {