Commit 31fecccb authored by David Sterba's avatar David Sterba
Browse files

btrfs: remove redundant csum buffer in btrfs_io_bio 



The io_bio tracks checksums and has an inline buffer or an allocated
one. And there's a third member that points to the right one, but we
don't need to use an extra pointer for that. Let btrfs_io_bio::csum
point to the right buffer and check that the inline buffer is not
accidentally freed.

This shrinks struct btrfs_io_bio by 8 bytes.

Reviewed-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 600b6cf4

fs/btrfs/file-item.c

+7 −5
Original line number Diff line number Diff line
@@ -144,7 +144,10 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans, 


static void btrfs_io_bio_endio_readpage(struct btrfs_io_bio *bio, int err)

{

	kfree(bio->csum_allocated);

	if (bio->csum != bio->csum_inline) {

		kfree(bio->csum);

		bio->csum = NULL;

	}

}



static blk_status_t __btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
@@ -175,13 +178,12 @@ static blk_status_t __btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio 
	nblocks = bio->bi_iter.bi_size >> inode->i_sb->s_blocksize_bits;

	if (!dst) {

		if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {

			btrfs_bio->csum_allocated = kmalloc_array(nblocks,

					csum_size, GFP_NOFS);

			if (!btrfs_bio->csum_allocated) {

			btrfs_bio->csum = kmalloc_array(nblocks, csum_size,

							GFP_NOFS);

			if (!btrfs_bio->csum) {

				btrfs_free_path(path);

				return BLK_STS_RESOURCE;

			}

			btrfs_bio->csum = btrfs_bio->csum_allocated;

			btrfs_bio->end_io = btrfs_io_bio_endio_readpage;

		} else {

			btrfs_bio->csum = btrfs_bio->csum_inline;

fs/btrfs/volumes.h

+0 −1
Original line number Diff line number Diff line
@@ -274,7 +274,6 @@ struct btrfs_io_bio { 
	u64 logical;

	u8 *csum;

	u8 csum_inline[BTRFS_BIO_INLINE_CSUM_SIZE];

	u8 *csum_allocated;

	btrfs_io_bio_end_io_t *end_io;

	struct bvec_iter iter;

	/*

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