Re: [f2fs-dev] [PATCH v2] f2fs: change i_compr_blocks of inode to atomic value

From: Jaegeuk Kim
Date: Thu Sep 03 2020 - 13:48:09 EST

On 09/03, Daeho Jeong wrote:
> From: Daeho Jeong <daehojeong@xxxxxxxxxx>
>
> writepages() can be concurrently invoked for the same file by different
> threads such as a thread fsyncing the file and a kworker kernel thread.
> So, changing i_compr_blocks without protection is racy and we need to
> protect it by changing it with atomic type value. Plus, we don't need
> a 64bit value for i_compr_blocks, so just we will use a atomic value,
> not atomic64.
>
> Signed-off-by: Daeho Jeong <daehojeong@xxxxxxxxxx>
> ---
> Changes in v2:
> - Change atomic64 to atomic and remove unnecessary part
> ---
> fs/f2fs/f2fs.h | 18 ++++++++----------
> fs/f2fs/file.c | 22 ++++++++++++----------
> fs/f2fs/inode.c | 11 +++++++----
> fs/f2fs/super.c | 1 +
> 4 files changed, 28 insertions(+), 24 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index f60414805e05..f6b8ac10a55c 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -801,7 +801,7 @@ struct f2fs_inode_info {
> struct timespec64 i_disk_time[4];/* inode disk times */
>
> /* for file compress */
> - u64 i_compr_blocks; /* # of compressed blocks */
> + atomic_t i_compr_blocks; /* # of compressed blocks */
> unsigned char i_compress_algorithm; /* algorithm type */
> unsigned char i_log_cluster_size; /* log of cluster size */
> unsigned int i_cluster_size; /* cluster size */
> @@ -3936,12 +3936,9 @@ static inline u64 f2fs_disable_compressed_file(struct inode *inode)
>
> if (!f2fs_compressed_file(inode))
> return 0;
> - if (S_ISREG(inode->i_mode)) {
> - if (get_dirty_pages(inode))
> - return 1;
> - if (fi->i_compr_blocks)
> - return fi->i_compr_blocks;
> - }
> + if (S_ISREG(inode->i_mode) &&
> + (get_dirty_pages(inode) || atomic_read(&fi->i_compr_blocks)))
> + return 1;

Please keep the original flow in this patch which says swithing to atomic.
Instead, it'd be better to have another patch which cleans up
f2fs_disable_compressed_file() having "bool" as a return value.

>
> fi->i_flags &= ~F2FS_COMPR_FL;
> stat_dec_compr_inode(inode);
> @@ -4057,16 +4054,17 @@ static inline void f2fs_i_compr_blocks_update(struct inode *inode,
> u64 blocks, bool add)
> {
> int diff = F2FS_I(inode)->i_cluster_size - blocks;
> + struct f2fs_inode_info *fi = F2FS_I(inode);
>
> /* don't update i_compr_blocks if saved blocks were released */
> - if (!add && !F2FS_I(inode)->i_compr_blocks)
> + if (!add && !atomic_read(&fi->i_compr_blocks))
> return;
>
> if (add) {
> - F2FS_I(inode)->i_compr_blocks += diff;
> + atomic_add(diff, &fi->i_compr_blocks);
> stat_add_compr_blocks(inode, diff);
> } else {
> - F2FS_I(inode)->i_compr_blocks -= diff;
> + atomic_sub(diff, &fi->i_compr_blocks);
> stat_sub_compr_blocks(inode, diff);
> }
> f2fs_mark_inode_dirty_sync(inode, true);
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index cc7f5670390f..adc4acad488a 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -564,7 +564,7 @@ void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count)
> bool compressed_cluster = false;
> int cluster_index = 0, valid_blocks = 0;
> int cluster_size = F2FS_I(dn->inode)->i_cluster_size;
> - bool released = !F2FS_I(dn->inode)->i_compr_blocks;
> + bool released = !atomic_read(&F2FS_I(dn->inode)->i_compr_blocks);
>
> if (IS_INODE(dn->node_page) && f2fs_has_extra_attr(dn->inode))
> base = get_extra_isize(dn->inode);
> @@ -3436,7 +3436,7 @@ static int f2fs_get_compress_blocks(struct file *filp, unsigned long arg)
> if (!f2fs_compressed_file(inode))
> return -EINVAL;
>
> - blocks = F2FS_I(inode)->i_compr_blocks;
> + blocks = atomic_read(&F2FS_I(inode)->i_compr_blocks);
> return put_user(blocks, (u64 __user *)arg);
> }
>
> @@ -3535,7 +3535,7 @@ static int f2fs_release_compress_blocks(struct file *filp, unsigned long arg)
> if (ret)
> goto out;
>
> - if (!F2FS_I(inode)->i_compr_blocks)
> + if (!atomic_read(&F2FS_I(inode)->i_compr_blocks))
> goto out;
>
> F2FS_I(inode)->i_flags |= F2FS_IMMUTABLE_FL;
> @@ -3588,14 +3588,15 @@ static int f2fs_release_compress_blocks(struct file *filp, unsigned long arg)
>
> if (ret >= 0) {
> ret = put_user(released_blocks, (u64 __user *)arg);
> - } else if (released_blocks && F2FS_I(inode)->i_compr_blocks) {
> + } else if (released_blocks &&
> + atomic_read(&F2FS_I(inode)->i_compr_blocks)) {
> set_sbi_flag(sbi, SBI_NEED_FSCK);
> f2fs_warn(sbi, "%s: partial blocks were released i_ino=%lx "
> - "iblocks=%llu, released=%u, compr_blocks=%llu, "
> + "iblocks=%llu, released=%u, compr_blocks=%u, "
> "run fsck to fix.",
> __func__, inode->i_ino, inode->i_blocks,
> released_blocks,
> - F2FS_I(inode)->i_compr_blocks);
> + atomic_read(&F2FS_I(inode)->i_compr_blocks));
> }
>
> return ret;
> @@ -3683,7 +3684,7 @@ static int f2fs_reserve_compress_blocks(struct file *filp, unsigned long arg)
> if (ret)
> return ret;
>
> - if (F2FS_I(inode)->i_compr_blocks)
> + if (atomic_read(&F2FS_I(inode)->i_compr_blocks))
> goto out;
>
> f2fs_balance_fs(F2FS_I_SB(inode), true);
> @@ -3747,14 +3748,15 @@ static int f2fs_reserve_compress_blocks(struct file *filp, unsigned long arg)
>
> if (ret >= 0) {
> ret = put_user(reserved_blocks, (u64 __user *)arg);
> - } else if (reserved_blocks && F2FS_I(inode)->i_compr_blocks) {
> + } else if (reserved_blocks &&
> + atomic_read(&F2FS_I(inode)->i_compr_blocks)) {
> set_sbi_flag(sbi, SBI_NEED_FSCK);
> f2fs_warn(sbi, "%s: partial blocks were released i_ino=%lx "
> - "iblocks=%llu, reserved=%u, compr_blocks=%llu, "
> + "iblocks=%llu, reserved=%u, compr_blocks=%u, "
> "run fsck to fix.",
> __func__, inode->i_ino, inode->i_blocks,
> reserved_blocks,
> - F2FS_I(inode)->i_compr_blocks);
> + atomic_read(&F2FS_I(inode)->i_compr_blocks));
> }
>
> return ret;
> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> index 66969ae852b9..2ed935c13aed 100644
> --- a/fs/f2fs/inode.c
> +++ b/fs/f2fs/inode.c
> @@ -442,7 +442,8 @@ static int do_read_inode(struct inode *inode)
> (fi->i_flags & F2FS_COMPR_FL)) {
> if (F2FS_FITS_IN_INODE(ri, fi->i_extra_isize,
> i_log_cluster_size)) {
> - fi->i_compr_blocks = le64_to_cpu(ri->i_compr_blocks);
> + atomic_set(&fi->i_compr_blocks,
> + le64_to_cpu(ri->i_compr_blocks));
> fi->i_compress_algorithm = ri->i_compress_algorithm;
> fi->i_log_cluster_size = ri->i_log_cluster_size;
> fi->i_cluster_size = 1 << fi->i_log_cluster_size;
> @@ -460,7 +461,7 @@ static int do_read_inode(struct inode *inode)
> stat_inc_inline_inode(inode);
> stat_inc_inline_dir(inode);
> stat_inc_compr_inode(inode);
> - stat_add_compr_blocks(inode, F2FS_I(inode)->i_compr_blocks);
> + stat_add_compr_blocks(inode, atomic_read(&fi->i_compr_blocks));
>
> return 0;
> }
> @@ -619,7 +620,8 @@ void f2fs_update_inode(struct inode *inode, struct page *node_page)
> F2FS_FITS_IN_INODE(ri, F2FS_I(inode)->i_extra_isize,
> i_log_cluster_size)) {
> ri->i_compr_blocks =
> - cpu_to_le64(F2FS_I(inode)->i_compr_blocks);
> + cpu_to_le64(atomic_read(
> + &F2FS_I(inode)->i_compr_blocks));
> ri->i_compress_algorithm =
> F2FS_I(inode)->i_compress_algorithm;
> ri->i_log_cluster_size =
> @@ -768,7 +770,8 @@ void f2fs_evict_inode(struct inode *inode)
> stat_dec_inline_dir(inode);
> stat_dec_inline_inode(inode);
> stat_dec_compr_inode(inode);
> - stat_sub_compr_blocks(inode, F2FS_I(inode)->i_compr_blocks);
> + stat_sub_compr_blocks(inode,
> + atomic_read(&F2FS_I(inode)->i_compr_blocks));
>
> if (likely(!f2fs_cp_error(sbi) &&
> !is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 83bf9a02f83f..813aa207824c 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1011,6 +1011,7 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
>
> /* Initialize f2fs-specific inode info */
> atomic_set(&fi->dirty_pages, 0);
> + atomic_set(&fi->i_compr_blocks, 0);
> init_rwsem(&fi->i_sem);
> spin_lock_init(&fi->i_size_lock);
> INIT_LIST_HEAD(&fi->dirty_list);
> --
> 2.28.0.526.ge36021eeef-goog
>
>
>
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