ext4: add ability to return parsed options from parse_options

Before this patch, the function parse_options() was returning
journal_devnum and journal_ioprio variables to the caller. This patch
generalizes that interface to allow parse_options to return any parsed
options to return back to the caller. In this patch series, it gets
used to capture the value of "mb_optimize_scan=%u" mount option.

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20210401172129.189766-3-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7b937a84f657cddfe6c4a61c8a11fcf61c323a47..0ef82e646100b6213aebcc048e4fcdef12f58958 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2090,9 +2090,14 @@ static int ext4_set_test_dummy_encryption(struct super_block *sb,
        return 1;
 }
 
+struct ext4_parsed_options {
+       unsigned long journal_devnum;
+       unsigned int journal_ioprio;
+};
+
 static int handle_mount_opt(struct super_block *sb, char *opt, int token,
-                           substring_t *args, unsigned long *journal_devnum,
-                           unsigned int *journal_ioprio, int is_remount)
+                           substring_t *args, struct ext4_parsed_options *parsed_opts,
+                           int is_remount)
 {
        struct ext4_sb_info *sbi = EXT4_SB(sb);
        const struct mount_opts *m;
@@ -2249,7 +2254,7 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
                                 "Cannot specify journal on remount");
                        return -1;
                }
-               *journal_devnum = arg;
+               parsed_opts->journal_devnum = arg;
        } else if (token == Opt_journal_path) {
                char *journal_path;
                struct inode *journal_inode;
@@ -2285,7 +2290,7 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
                        return -1;
                }
 
-               *journal_devnum = new_encode_dev(journal_inode->i_rdev);
+               parsed_opts->journal_devnum = new_encode_dev(journal_inode->i_rdev);
                path_put(&path);
                kfree(journal_path);
        } else if (token == Opt_journal_ioprio) {
@@ -2294,7 +2299,7 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
                                 " (must be 0-7)");
                        return -1;
                }
-               *journal_ioprio =
+               parsed_opts->journal_ioprio =
                        IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, arg);
        } else if (token == Opt_test_dummy_encryption) {
                return ext4_set_test_dummy_encryption(sb, opt, &args[0],
@@ -2411,8 +2416,7 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 }
 
 static int parse_options(char *options, struct super_block *sb,
-                        unsigned long *journal_devnum,
-                        unsigned int *journal_ioprio,
+                        struct ext4_parsed_options *ret_opts,
                         int is_remount)
 {
        struct ext4_sb_info __maybe_unused *sbi = EXT4_SB(sb);
@@ -2432,8 +2436,8 @@ static int parse_options(char *options, struct super_block *sb,
                 */
                args[0].to = args[0].from = NULL;
                token = match_token(p, tokens, args);
-               if (handle_mount_opt(sb, p, token, args, journal_devnum,
-                                    journal_ioprio, is_remount) < 0)
+               if (handle_mount_opt(sb, p, token, args, ret_opts,
+                                    is_remount) < 0)
                        return 0;
        }
 #ifdef CONFIG_QUOTA
@@ -4015,7 +4019,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
        ext4_fsblk_t sb_block = get_sb_block(&data);
        ext4_fsblk_t logical_sb_block;
        unsigned long offset = 0;
-       unsigned long journal_devnum = 0;
        unsigned long def_mount_opts;
        struct inode *root;
        const char *descr;
@@ -4026,8 +4029,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
        int needs_recovery, has_huge_files;
        __u64 blocks_count;
        int err = 0;
-       unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
        ext4_group_t first_not_zeroed;
+       struct ext4_parsed_options parsed_opts;
+
+       /* Set defaults for the variables that will be set during parsing */
+       parsed_opts.journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
+       parsed_opts.journal_devnum = 0;
 
        if ((data && !orig_data) || !sbi)
                goto out_free_base;
@@ -4273,8 +4280,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
                                              GFP_KERNEL);
                if (!s_mount_opts)
                        goto failed_mount;
-               if (!parse_options(s_mount_opts, sb, &journal_devnum,
-                                  &journal_ioprio, 0)) {
+               if (!parse_options(s_mount_opts, sb, &parsed_opts, 0)) {
                        ext4_msg(sb, KERN_WARNING,
                                 "failed to parse options in superblock: %s",
                                 s_mount_opts);
@@ -4282,8 +4288,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
                kfree(s_mount_opts);
        }
        sbi->s_def_mount_opt = sbi->s_mount_opt;
-       if (!parse_options((char *) data, sb, &journal_devnum,
-                          &journal_ioprio, 0))
+       if (!parse_options((char *) data, sb, &parsed_opts, 0))
                goto failed_mount;
 
 #ifdef CONFIG_UNICODE
@@ -4768,7 +4773,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
         * root first: it may be modified in the journal!
         */
        if (!test_opt(sb, NOLOAD) && ext4_has_feature_journal(sb)) {
-               err = ext4_load_journal(sb, es, journal_devnum);
+               err = ext4_load_journal(sb, es, parsed_opts.journal_devnum);
                if (err)
                        goto failed_mount3a;
        } else if (test_opt(sb, NOLOAD) && !sb_rdonly(sb) &&
@@ -4868,7 +4873,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
                goto failed_mount_wq;
        }
 
-       set_task_ioprio(sbi->s_journal->j_task, journal_ioprio);
+       set_task_ioprio(sbi->s_journal->j_task, parsed_opts.journal_ioprio);
 
        sbi->s_journal->j_submit_inode_data_buffers =
                ext4_journal_submit_inode_data_buffers;
@@ -5807,13 +5812,16 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
        struct ext4_mount_options old_opts;
        int enable_quota = 0;
        ext4_group_t g;
-       unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
        int err = 0;
 #ifdef CONFIG_QUOTA
        int i, j;
        char *to_free[EXT4_MAXQUOTAS];
 #endif
        char *orig_data = kstrdup(data, GFP_KERNEL);
+       struct ext4_parsed_options parsed_opts;
+
+       parsed_opts.journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
+       parsed_opts.journal_devnum = 0;
 
        if (data && !orig_data)
                return -ENOMEM;
@@ -5844,7 +5852,8 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
                        old_opts.s_qf_names[i] = NULL;
 #endif
        if (sbi->s_journal && sbi->s_journal->j_task->io_context)
-               journal_ioprio = sbi->s_journal->j_task->io_context->ioprio;
+               parsed_opts.journal_ioprio =
+                       sbi->s_journal->j_task->io_context->ioprio;
 
        /*
         * Some options can be enabled by ext4 and/or by VFS mount flag
@@ -5854,7 +5863,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
        vfs_flags = SB_LAZYTIME | SB_I_VERSION;
        sb->s_flags = (sb->s_flags & ~vfs_flags) | (*flags & vfs_flags);
 
-       if (!parse_options(data, sb, NULL, &journal_ioprio, 1)) {
+       if (!parse_options(data, sb, &parsed_opts, 1)) {
                err = -EINVAL;
                goto restore_opts;
        }
@@ -5904,7 +5913,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 
        if (sbi->s_journal) {
                ext4_init_journal_params(sb, sbi->s_journal);
-               set_task_ioprio(sbi->s_journal->j_task, journal_ioprio);
+               set_task_ioprio(sbi->s_journal->j_task, parsed_opts.journal_ioprio);
        }
 
        /* Flush outstanding errors before changing fs state */