On 2018/2/28 13:09, Jaegeuk Kim wrote:
> Change log from v1:
> - add doc :)
>
> This patch adds an mount option, "alloc_mode=%s" having two options, "default"
> and "reuse".
>
> In "alloc_mode=reuse" case, f2fs starts to allocate segments from 0'th segment
> all the time to reassign segments. It'd be useful for small-sized eMMC parts.
We have to restore old alloc_mode if we encounter any failure in ->remount,
right?
Thanks,
>
> Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org>
> ---
> Documentation/filesystems/f2fs.txt | 2 ++
> fs/f2fs/f2fs.h | 8 ++++++++
> fs/f2fs/segment.c | 5 +++++
> fs/f2fs/super.c | 24 ++++++++++++++++++++++++
> 4 files changed, 39 insertions(+)
>
> diff --git a/Documentation/filesystems/f2fs.txt
> b/Documentation/filesystems/f2fs.txt
> index 0caf7da0a532..0409c47584ea 100644
> --- a/Documentation/filesystems/f2fs.txt
> +++ b/Documentation/filesystems/f2fs.txt
> @@ -180,6 +180,8 @@ whint_mode=%s Control which write hints are
> passed down to block
> down hints. In "user-based" mode, f2fs tries to pass
> down hints given by users. And in "fs-based" mode,
> f2fs
> passes down hints with its policy.
> +alloc_mode=%s Adjust block allocation policy, which supports "reuse"
> + and "default".
>
>
> ================================================================================
> DEBUGFS ENTRIES
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index f68ece08b5a2..d1bfdf691afc 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1043,6 +1043,11 @@ enum {
> WHINT_MODE_FS, /* pass down hints with F2FS policy */
> };
>
> +enum {
> + ALLOC_MODE_DEFAULT, /* stay default */
> + ALLOC_MODE_REUSE, /* reuse segments as much as possible */
> +};
> +
> struct f2fs_sb_info {
> struct super_block *sb; /* pointer to VFS super block */
> struct proc_dir_entry *s_proc; /* proc entry */
> @@ -1229,6 +1234,9 @@ struct f2fs_sb_info {
> #endif
> /* For which write hints are passed down to block layer */
> int whint_mode;
> +
> + /* segment allocation policy */
> + int alloc_mode;
> };
>
> #ifdef CONFIG_F2FS_FAULT_INJECTION
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 0646d5de8cd0..5e5e2936a26a 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -2170,6 +2170,11 @@ static unsigned int __get_next_segno(struct
> f2fs_sb_info *sbi, int type)
>
> if (SIT_I(sbi)->last_victim[ALLOC_NEXT])
> return SIT_I(sbi)->last_victim[ALLOC_NEXT];
> +
> + /* find segments from 0 to reuse freed segments */
> + if (sbi->alloc_mode == ALLOC_MODE_REUSE)
> + return 0;
> +
> return CURSEG_I(sbi, type)->segno;
> }
>
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 2d832866720c..1345ef167140 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -130,6 +130,7 @@ enum {
> Opt_jqfmt_vfsv0,
> Opt_jqfmt_vfsv1,
> Opt_whint,
> + Opt_alloc,
> Opt_err,
> };
>
> @@ -184,6 +185,7 @@ static match_table_t f2fs_tokens = {
> {Opt_jqfmt_vfsv0, "jqfmt=vfsv0"},
> {Opt_jqfmt_vfsv1, "jqfmt=vfsv1"},
> {Opt_whint, "whint_mode=%s"},
> + {Opt_alloc, "alloc_mode=%s"},
> {Opt_err, NULL},
> };
>
> @@ -700,6 +702,23 @@ static int parse_options(struct super_block *sb, char
> *options)
> }
> kfree(name);
> break;
> + case Opt_alloc:
> + name = match_strdup(&args[0]);
> + if (!name)
> + return -ENOMEM;
> +
> + if (strlen(name) == 7 &&
> + !strncmp(name, "default", 7)) {
> + sbi->alloc_mode = ALLOC_MODE_DEFAULT;
> + } else if (strlen(name) == 5 &&
> + !strncmp(name, "reuse", 5)) {
> + sbi->alloc_mode = ALLOC_MODE_REUSE;
> + } else {
> + kfree(name);
> + return -EINVAL;
> + }
> + kfree(name);
> + break;
> default:
> f2fs_msg(sb, KERN_ERR,
> "Unrecognized mount option \"%s\" or missing
> value",
> @@ -1264,6 +1283,10 @@ static int f2fs_show_options(struct seq_file *seq,
> struct dentry *root)
> else if (sbi->whint_mode == WHINT_MODE_FS)
> seq_printf(seq, ",whint_mode=%s", "fs-based");
>
> + if (sbi->alloc_mode == ALLOC_MODE_DEFAULT)
> + seq_printf(seq, ",alloc_mode=%s", "default");
> + else if (sbi->alloc_mode == ALLOC_MODE_REUSE)
> + seq_printf(seq, ",alloc_mode=%s", "reuse");
> return 0;
> }
>
> @@ -1273,6 +1296,7 @@ static void default_options(struct f2fs_sb_info *sbi)
> sbi->active_logs = NR_CURSEG_TYPE;
> sbi->inline_xattr_size = DEFAULT_INLINE_XATTR_ADDRS;
> sbi->whint_mode = WHINT_MODE_OFF;
> + sbi->alloc_mode = ALLOC_MODE_DEFAULT;
>
> set_opt(sbi, BG_GC);
> set_opt(sbi, INLINE_XATTR);
>
