mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

f2fs: extend stat_lock to avoid potential race in statfs 

There are multiple calculations and reads of fields of sbi that should
be protected by stat_lock. As stat_lock is not used to read these
values in statfs, this can lead to inconsistent results.
Extend the locking to prevent this issue.
Commit c9c8ed50d9 ("f2fs: fix to avoid potential race on
sbi->unusable_block_count access/update")
already added the use of sbi->stat_lock in statfs in
order to make the calculation of multiple, different fields atomic so
that results are consistent. This is similar to that patch regarding the
change in statfs.

Signed-off-by: Niels Dossche <dossche.niels@gmail.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Niels Dossche 2022-04-22 20:05:04 +02:00 committed by Jaegeuk Kim
parent a7b8618aa2
commit 4de851459e
1 changed files with 8 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
fs/f2fs/super.c
View File

@ -1707,18 +1707,23 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
block_t total_count, user_block_count, start_count;
u64 avail_node_count;
unsigned int total_valid_node_count;
total_count = le64_to_cpu(sbi->raw_super->block_count);
user_block_count = sbi->user_block_count;
start_count = le32_to_cpu(sbi->raw_super->segment0_blkaddr);
buf->f_type = F2FS_SUPER_MAGIC;
buf->f_bsize = sbi->blocksize;
buf->f_blocks = total_count - start_count;
spin_lock(&sbi->stat_lock);
user_block_count = sbi->user_block_count;
total_valid_node_count = valid_node_count(sbi);
avail_node_count = sbi->total_node_count - F2FS_RESERVED_NODE_NUM;
buf->f_bfree = user_block_count - valid_user_blocks(sbi) -
sbi->current_reserved_blocks;
spin_lock(&sbi->stat_lock);
if (unlikely(buf->f_bfree <= sbi->unusable_block_count))
buf->f_bfree = 0;
else
@ -1731,14 +1736,12 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
else
buf->f_bavail = 0;
avail_node_count = sbi->total_node_count - F2FS_RESERVED_NODE_NUM;
if (avail_node_count > user_block_count) {
buf->f_files = user_block_count;
buf->f_ffree = buf->f_bavail;
} else {
buf->f_files = avail_node_count;
buf->f_ffree = min(avail_node_count - valid_node_count(sbi),
buf->f_ffree = min(avail_node_count - total_valid_node_count,
buf->f_bavail);
}