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exfat: fix soft lockup in exfat_clear_bitmap

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bitmap clear loop will take long time in __exfat_free_cluster()
if data size of file/dir enty is invalid.
If cluster bit in bitmap is already clear, stop clearing bitmap go to
out of loop.

Fixes: 31023864e6 ("exfat: add fat entry operations")
Reported-by: Kun Hu <huk23@m.fudan.edu.cn>, Jiaji Qin <jjtan24@m.fudan.edu.cn>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
This commit is contained in:
Namjae Jeon 2025-01-31 12:55:55 +09:00
parent 6697f819a1
commit 9da33619e0
3 changed files with 16 additions and 7 deletions
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10
fs/exfat/balloc.c
View file

@ -141,7 +141,7 @@ int exfat_set_bitmap(struct inode *inode, unsigned int clu, bool sync)
return 0;
}
void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
int exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
{
int i, b;
unsigned int ent_idx;
@ -150,13 +150,17 @@ void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
struct exfat_mount_options *opts = &sbi->options;
if (!is_valid_cluster(sbi, clu))
return;
return -EIO;
ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
if (!test_bit_le(b, sbi->vol_amap[i]->b_data))
return -EIO;
clear_bit_le(b, sbi->vol_amap[i]->b_data);
exfat_update_bh(sbi->vol_amap[i], sync);
if (opts->discard) {
@ -171,6 +175,8 @@ void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
opts->discard = 0;
}
}
return 0;
}
/*

2
fs/exfat/exfat_fs.h
View file

@ -456,7 +456,7 @@ int exfat_count_num_clusters(struct super_block *sb,
int exfat_load_bitmap(struct super_block *sb);
void exfat_free_bitmap(struct exfat_sb_info *sbi);
int exfat_set_bitmap(struct inode *inode, unsigned int clu, bool sync);
void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync);
int exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync);
unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu);
int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count);
int exfat_trim_fs(struct inode *inode, struct fstrim_range *range);

11
fs/exfat/fatent.c
View file

@ -175,6 +175,7 @@ static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain
BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(clu));
if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
int err;
unsigned int last_cluster = p_chain->dir + p_chain->size - 1;
do {
bool sync = false;
@ -189,7 +190,9 @@ static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain
cur_cmap_i = next_cmap_i;
}
exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
err = exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
if (err)
break;
clu++;
num_clusters++;
} while (num_clusters < p_chain->size);
@ -210,12 +213,13 @@ static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain
cur_cmap_i = next_cmap_i;
}
exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
if (exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode))))
break;
clu = n_clu;
num_clusters++;
if (err)
goto dec_used_clus;
break;
if (num_clusters >= sbi->num_clusters - EXFAT_FIRST_CLUSTER) {
/*
@ -229,7 +233,6 @@ static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain
} while (clu != EXFAT_EOF_CLUSTER);
}
dec_used_clus:
sbi->used_clusters -= num_clusters;
return 0;
}