Commit 256694b2 authored by Chi Zhiling's avatar Chi Zhiling Committed by Namjae Jeon
Browse files

exfat: support multi-cluster for exfat_map_cluster 



This patch introduces a parameter 'count' to support fetching multiple
clusters in exfat_map_cluster. The returned 'count' indicates the number
of consecutive clusters, or 0 when the input cluster offset is past EOF.

And the 'count' is also an input parameter for the caller to specify the
required number of clusters.

Only NO_FAT_CHAIN files enable multi-cluster fetching in this patch.

After this patch, the time proportion of exfat_get_block has decreased,
The performance data is as follows:

Cluster size: 512 bytes
Sequential read of a 30GB NO_FAT_CHAIN file:
2.4GB/s -> 2.5 GB/s
proportion of exfat_get_block:
10.8% -> 0.02%

Signed-off-by: default avatarChi Zhiling <chizhiling@kylinos.cn>
Reviewed-by: default avatarYuezhang Mo <Yuezhang.Mo@sony.com>
Signed-off-by: default avatarNamjae Jeon <linkinjeon@kernel.org>
parent 88a936b7

fs/exfat/inode.c

+17 −13
Original line number Diff line number Diff line
@@ -124,7 +124,7 @@ void exfat_sync_inode(struct inode *inode) 
 * *clu = (~0), if it's unable to allocate a new cluster

 */

static int exfat_map_cluster(struct inode *inode, unsigned int clu_offset,

		unsigned int *clu, int create)

		unsigned int *clu, unsigned int *count, int create)

{

	int ret;

	unsigned int last_clu;
@@ -147,20 +147,23 @@ static int exfat_map_cluster(struct inode *inode, unsigned int clu_offset, 


	*clu = last_clu = ei->start_clu;



	if (ei->flags == ALLOC_NO_FAT_CHAIN) {

		if (clu_offset > 0 && *clu != EXFAT_EOF_CLUSTER) {

			last_clu += clu_offset - 1;



			if (clu_offset == num_clusters)

				*clu = EXFAT_EOF_CLUSTER;

			else

	if (*clu == EXFAT_EOF_CLUSTER) {

		*count = 0;

	} else if (ei->flags == ALLOC_NO_FAT_CHAIN) {

		last_clu += num_clusters - 1;

		if (clu_offset < num_clusters) {

			*clu += clu_offset;

			*count = min(num_clusters - clu_offset, *count);

		} else {

			*clu = EXFAT_EOF_CLUSTER;

			*count = 0;

		}

	} else {

		int err = exfat_get_cluster(inode, clu_offset,

				clu, &last_clu);

		if (err)

			return -EIO;

		*count = (*clu == EXFAT_EOF_CLUSTER) ? 0 : 1;

	}



	if (*clu == EXFAT_EOF_CLUSTER) {
@@ -232,7 +235,7 @@ static int exfat_map_cluster(struct inode *inode, unsigned int clu_offset, 
				num_to_be_allocated--;

			}

		}



		*count = 1;

	}



	/* hint information */
@@ -251,7 +254,7 @@ static int exfat_get_block(struct inode *inode, sector_t iblock, 
	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;

	int err = 0;

	unsigned long mapped_blocks = 0;

	unsigned int cluster, sec_offset;

	unsigned int cluster, sec_offset, count;

	sector_t last_block;

	sector_t phys = 0;

	sector_t valid_blks;
@@ -264,8 +267,9 @@ static int exfat_get_block(struct inode *inode, sector_t iblock, 
		goto done;



	/* Is this block already allocated? */

	count = EXFAT_B_TO_CLU_ROUND_UP(bh_result->b_size, sbi);

	err = exfat_map_cluster(inode, iblock >> sbi->sect_per_clus_bits,

			&cluster, create);

			&cluster, &count, create);

	if (err) {

		if (err != -ENOSPC)

			exfat_fs_error_ratelimit(sb,
@@ -281,7 +285,7 @@ static int exfat_get_block(struct inode *inode, sector_t iblock, 
	sec_offset = iblock & (sbi->sect_per_clus - 1);



	phys = exfat_cluster_to_sector(sbi, cluster) + sec_offset;

	mapped_blocks = sbi->sect_per_clus - sec_offset;

	mapped_blocks = ((unsigned long)count << sbi->sect_per_clus_bits) - sec_offset;

	max_blocks = min(mapped_blocks, max_blocks);



	map_bh(bh_result, sb, phys);