f2fs: add mount option for segment allocation policy

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.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt
index 0caf7da..0409c47 100644 (file)
--- 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 3bb4e94..833c9bc 100644 (file)
--- 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 0646d5d..5e5e293 100644 (file)
--- 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 06da158..16d157e 100644 (file)
--- 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);
@@ -1314,6 +1338,7 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
        bool need_stop_gc = false;
        bool no_extent_cache = !test_opt(sbi, EXTENT_CACHE);
        int old_whint_mode = sbi->whint_mode;
+       int old_alloc_mode = sbi->alloc_mode;
 #ifdef CONFIG_F2FS_FAULT_INJECTION
        struct f2fs_fault_info ffi = sbi->fault_info;
 #endif
@@ -1463,6 +1488,7 @@ restore_opts:
                sbi->s_qf_names[i] = s_qf_names[i];
        }
 #endif
+       sbi->alloc_mode = old_alloc_mode;
        sbi->whint_mode = old_whint_mode;
        sbi->mount_opt = org_mount_opt;
        sbi->active_logs = active_logs;