Gh0st
/
linux
mirror of https://github.com/torvalds/linux.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

exfat: optimize allocation bitmap loading time 

Loading the allocation bitmap is very slow if user set the small cluster
size on large partition.

For optimizing it, This patch uses sb_breadahead() read the allocation
bitmap. It will improve the mount time.

The following is the result of about 4TB partition(2KB cluster size)
on my target.

without patch:
real 0m41.746s
user 0m0.011s
sys 0m0.000s

with patch:
real 0m2.525s
user 0m0.008s
sys 0m0.008s

Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Reviewed-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
This commit is contained in:
Namjae Jeon 2025-09-06 08:13:04 +09:00
parent cb8d6d4aa0
commit 9fd688678d
1 changed files with 13 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
fs/exfat/balloc.c
View File

@ -7,6 +7,7 @@
#include <linux/slab.h>
#include <linux/bitmap.h>
#include <linux/buffer_head.h>
#include <linux/backing-dev.h>
#include "exfat_raw.h"
#include "exfat_fs.h"
@ -73,9 +74,11 @@ static int exfat_allocate_bitmap(struct super_block *sb,
struct exfat_dentry *ep)
{
struct exfat_sb_info *sbi = EXFAT_SB(sb);
struct blk_plug plug;
long long map_size;
unsigned int i, j, need_map_size;
sector_t sector;
unsigned int max_ra_count;
sbi->map_clu = le32_to_cpu(ep->dentry.bitmap.start_clu);
map_size = le64_to_cpu(ep->dentry.bitmap.size);
@ -99,7 +102,17 @@ static int exfat_allocate_bitmap(struct super_block *sb,
return -ENOMEM;
sector = exfat_cluster_to_sector(sbi, sbi->map_clu);
max_ra_count = min(sb->s_bdi->ra_pages, sb->s_bdi->io_pages) <<
(PAGE_SHIFT - sb->s_blocksize_bits);
for (i = 0; i < sbi->map_sectors; i++) {
/* Trigger the next readahead in advance. */
if (0 == (i % max_ra_count)) {
blk_start_plug(&plug);
for (j = i; j < min(max_ra_count, sbi->map_sectors - i) + i; j++)
sb_breadahead(sb, sector + j);
blk_finish_plug(&plug);
}
sbi->vol_amap[i] = sb_bread(sb, sector + i);
if (!sbi->vol_amap[i])
goto err_out;