From 4de851459ea65ac8cf4313af648ec9cf16b72562 Mon Sep 17 00:00:00 2001 From: Niels Dossche Date: Fri, 22 Apr 2022 20:05:04 +0200 Subject: 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 c9c8ed50d94c ("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 Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/super.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'fs/f2fs') diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 4368f90571bd..cb50f8b2e41a 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -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); } -- cgit v1.2.3