Re: [f2fs-dev] [PATCH v3] f2fs: add reserved blocks for root user

From: Chao Yu
Date: Tue Jan 02 2018 - 01:26:09 EST

On 2018/1/1 9:29, Jaegeuk Kim wrote:
> This patch allows root to reserve some blocks via mount option.
>
> "-o reserve_root=N" means N x 4KB-sized blocks for root only.
>
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
>
> Change log from v2:
> - wrong submission. :P
>
> fs/f2fs/f2fs.h | 26 ++++++++++++++++++++++----
> fs/f2fs/super.c | 26 +++++++++++++++++++++++---
> fs/f2fs/sysfs.c | 3 ++-
> 3 files changed, 47 insertions(+), 8 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 5f7f42267221..123d875f7293 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -95,6 +95,7 @@ extern char *fault_name[FAULT_MAX];
> #define F2FS_MOUNT_PRJQUOTA 0x00200000
> #define F2FS_MOUNT_QUOTA 0x00400000
> #define F2FS_MOUNT_INLINE_XATTR_SIZE 0x00800000
> +#define F2FS_MOUNT_RESERVE_ROOT 0x01000000
>
> #define clear_opt(sbi, option) ((sbi)->mount_opt.opt &= ~F2FS_MOUNT_##option)
> #define set_opt(sbi, option) ((sbi)->mount_opt.opt |= F2FS_MOUNT_##option)
> @@ -1110,6 +1111,7 @@ struct f2fs_sb_info {
> block_t last_valid_block_count; /* for recovery */
> block_t reserved_blocks; /* configurable reserved blocks */
> block_t current_reserved_blocks; /* current reserved blocks */
> + block_t root_reserved_blocks; /* root reserved blocks */
>
> unsigned int nquota_files; /* # of quota sysfile */
>
> @@ -1562,6 +1564,12 @@ static inline bool f2fs_has_xattr_block(unsigned int ofs)
> return ofs == XATTR_NODE_OFFSET;
> }
>
> +static inline block_t reserve_root_limit(struct f2fs_sb_info *sbi)
> +{
> + /* limit is 0.2% */

Should be 2% according to below calculation?

> + return (sbi->user_block_count << 1) / 100;
> +}
> +
> static inline void f2fs_i_blocks_write(struct inode *, block_t, bool, bool);
> static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
> struct inode *inode, blkcnt_t *count)
> @@ -1591,11 +1599,17 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
> sbi->total_valid_block_count += (block_t)(*count);
> avail_user_block_count = sbi->user_block_count -
> sbi->current_reserved_blocks;
> +
> + if (!(test_opt(sbi, RESERVE_ROOT) && capable(CAP_SYS_RESOURCE)))

How about adding uid & gid verification also like ext4?

As this is a mount option, in ->remount_fs, we should consider to recover
original reserved block number if we encounter some error during remount.

Thanks,

> + avail_user_block_count -= sbi->root_reserved_blocks;
> +
> if (unlikely(sbi->total_valid_block_count > avail_user_block_count)) {
> diff = sbi->total_valid_block_count - avail_user_block_count;
> + if (diff > *count)
> + diff = *count;
> *count -= diff;
> release = diff;
> - sbi->total_valid_block_count = avail_user_block_count;
> + sbi->total_valid_block_count -= diff;
> if (!*count) {
> spin_unlock(&sbi->stat_lock);
> percpu_counter_sub(&sbi->alloc_valid_block_count, diff);
> @@ -1784,9 +1798,13 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
>
> spin_lock(&sbi->stat_lock);
>
> - valid_block_count = sbi->total_valid_block_count + 1;
> - if (unlikely(valid_block_count + sbi->current_reserved_blocks >
> - sbi->user_block_count)) {
> + valid_block_count = sbi->total_valid_block_count +
> + sbi->current_reserved_blocks + 1;
> +
> + if (!(test_opt(sbi, RESERVE_ROOT) && capable(CAP_SYS_RESOURCE)))
> + valid_block_count += sbi->root_reserved_blocks;
> +
> + if (unlikely(valid_block_count > sbi->user_block_count)) {
> spin_unlock(&sbi->stat_lock);
> goto enospc;
> }
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index cb876d905ca5..9221b013db98 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -107,6 +107,7 @@ enum {
> Opt_noextent_cache,
> Opt_noinline_data,
> Opt_data_flush,
> + Opt_reserve_root,
> Opt_mode,
> Opt_io_size_bits,
> Opt_fault_injection,
> @@ -157,6 +158,7 @@ static match_table_t f2fs_tokens = {
> {Opt_noextent_cache, "noextent_cache"},
> {Opt_noinline_data, "noinline_data"},
> {Opt_data_flush, "data_flush"},
> + {Opt_reserve_root, "reserve_root=%u"},
> {Opt_mode, "mode=%s"},
> {Opt_io_size_bits, "io_bits=%u"},
> {Opt_fault_injection, "fault_injection=%u"},
> @@ -488,6 +490,12 @@ static int parse_options(struct super_block *sb, char *options)
> case Opt_data_flush:
> set_opt(sbi, DATA_FLUSH);
> break;
> + case Opt_reserve_root:
> + if (args->from && match_int(args, &arg))
> + return -EINVAL;
> + sbi->root_reserved_blocks = arg;
> + set_opt(sbi, RESERVE_ROOT);
> + break;
> case Opt_mode:
> name = match_strdup(&args[0]);
>
> @@ -1005,10 +1013,12 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
> buf->f_bsize = sbi->blocksize;
>
> buf->f_blocks = total_count - start_count;
> - buf->f_bfree = user_block_count - valid_user_blocks(sbi) + ovp_count;
> + buf->f_bfree = user_block_count - valid_user_blocks(sbi) -
> + sbi->current_reserved_blocks +
> + sbi->root_reserved_blocks;
> buf->f_bavail = user_block_count - valid_user_blocks(sbi) -
> - sbi->current_reserved_blocks;
> -
> + sbi->current_reserved_blocks -
> + sbi->root_reserved_blocks;
> avail_node_count = sbi->total_node_count - sbi->nquota_files -
> F2FS_RESERVED_NODE_NUM;
>
> @@ -1136,6 +1146,9 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
> else if (test_opt(sbi, LFS))
> seq_puts(seq, "lfs");
> seq_printf(seq, ",active_logs=%u", sbi->active_logs);
> + if (test_opt(sbi, RESERVE_ROOT))
> + seq_printf(seq, ",reserve_root=%u",
> + sbi->root_reserved_blocks);
> if (F2FS_IO_SIZE_BITS(sbi))
> seq_printf(seq, ",io_size=%uKB", F2FS_IO_SIZE_KB(sbi));
> #ifdef CONFIG_F2FS_FAULT_INJECTION
> @@ -2571,6 +2584,13 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
> sbi->reserved_blocks = 0;
> sbi->current_reserved_blocks = 0;
>
> + if (test_opt(sbi, RESERVE_ROOT) &&
> + sbi->root_reserved_blocks > reserve_root_limit(sbi)) {
> + sbi->root_reserved_blocks = reserve_root_limit(sbi);
> + f2fs_msg(sb, KERN_INFO,
> + "Reduce reserved blocks for root = %u\n",
> + sbi->root_reserved_blocks);
> + }
> for (i = 0; i < NR_INODE_TYPE; i++) {
> INIT_LIST_HEAD(&sbi->inode_list[i]);
> spin_lock_init(&sbi->inode_lock[i]);
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 7e15cbc5b8e1..41887e6ec1b3 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -162,7 +162,8 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a,
> #endif
> if (a->struct_type == RESERVED_BLOCKS) {
> spin_lock(&sbi->stat_lock);
> - if (t > (unsigned long)sbi->user_block_count) {
> + if (t > (unsigned long)(sbi->user_block_count -
> + sbi->root_reserved_blocks)) {
> spin_unlock(&sbi->stat_lock);
> return -EINVAL;
> }
>