Commit dd11a5df authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

f2fs: avoid data race when deciding checkpoin in f2fs_sync_file 



When fs utilization is almost full, f2fs_sync_file should do checkpoint if
there is not enough space for roll-forward later. (i.e. space_for_roll_forward)
So, currently we have no lock for sbi->alloc_valid_block_count, resulting in
race condition.

In rare case, we can get -ENOSPC when doing roll-forward which triggers

	if (is_valid_blkaddr(sbi, dest, META_POR)) {
		if (src == NULL_ADDR) {
			err = reserve_new_block(&dn);
			f2fs_bug_on(sbi, err);
			...
		}
		...
	}
in do_recover_data.

So, this patch avoids that situation in advance.

Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 4dd6f977

fs/f2fs/f2fs.h

+11 −2
Original line number Diff line number Diff line
@@ -1147,24 +1147,33 @@ static inline void f2fs_i_blocks_write(struct inode *, blkcnt_t, bool); 
static inline bool inc_valid_block_count(struct f2fs_sb_info *sbi,

				 struct inode *inode, blkcnt_t *count)

{

	blkcnt_t diff;



#ifdef CONFIG_F2FS_FAULT_INJECTION

	if (time_to_inject(FAULT_BLOCK))

		return false;

#endif

	/*

	 * let's increase this in prior to actual block count change in order

	 * for f2fs_sync_file to avoid data races when deciding checkpoint.

	 */

	percpu_counter_add(&sbi->alloc_valid_block_count, (*count));



	spin_lock(&sbi->stat_lock);

	sbi->total_valid_block_count += (block_t)(*count);

	if (unlikely(sbi->total_valid_block_count > sbi->user_block_count)) {

		*count -= sbi->total_valid_block_count - sbi->user_block_count;

		diff = sbi->total_valid_block_count - sbi->user_block_count;

		*count -= diff;

		sbi->total_valid_block_count = sbi->user_block_count;

		if (!*count) {

			spin_unlock(&sbi->stat_lock);

			percpu_counter_sub(&sbi->alloc_valid_block_count, diff);

			return false;

		}

	}

	spin_unlock(&sbi->stat_lock);



	f2fs_i_blocks_write(inode, *count, true);

	percpu_counter_add(&sbi->alloc_valid_block_count, (*count));

	return true;

}

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