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SubjectRe: [PATCH] erofs: convert to use the new mount fs_context api
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Hi Xiang,

On 2019/12/26 10:16, Gao Xiang wrote:
> Hi Chao,
>
> On Thu, Dec 26, 2019 at 09:50:04AM +0800, Chao Yu wrote:
>> Convert the erofs to use new internal mount API as the old one will
>> be obsoleted and removed. This allows greater flexibility in
>> communication of mount parameters between userspace, the VFS and the
>> filesystem.
>>
>> See Documentation/filesystems/mount_api.txt for more information.
>>
>
> How about adding this line...
>
> Cc: David Howells <dhowells@redhat.com>
>
>> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>
> Could we resend this patch with the above commit message Cc fs_context
> owner as well since we are not quite sure if there are still some potential
> thing to consider... If he has some extra time and interest in it...

Sure, will resend soon...

Thanks,

>
> Thanks,
> Gao Xiang
>
>> ---
>> fs/erofs/internal.h | 2 +-
>> fs/erofs/super.c | 249 +++++++++++++++++++++-----------------------
>> 2 files changed, 118 insertions(+), 133 deletions(-)
>>
>> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
>> index 1ed5beff7d11..a5fac25db6af 100644
>> --- a/fs/erofs/internal.h
>> +++ b/fs/erofs/internal.h
>> @@ -102,13 +102,13 @@ struct erofs_sb_info {
>> #define set_opt(sbi, option) ((sbi)->mount_opt |= EROFS_MOUNT_##option)
>> #define test_opt(sbi, option) ((sbi)->mount_opt & EROFS_MOUNT_##option)
>>
>> -#ifdef CONFIG_EROFS_FS_ZIP
>> enum {
>> EROFS_ZIP_CACHE_DISABLED,
>> EROFS_ZIP_CACHE_READAHEAD,
>> EROFS_ZIP_CACHE_READAROUND
>> };
>>
>> +#ifdef CONFIG_EROFS_FS_ZIP
>> #define EROFS_LOCKED_MAGIC (INT_MIN | 0xE0F510CCL)
>>
>> /* basic unit of the workstation of a super_block */
>> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
>> index 057e6d7b5b7f..b90713760885 100644
>> --- a/fs/erofs/super.c
>> +++ b/fs/erofs/super.c
>> @@ -10,6 +10,8 @@
>> #include <linux/parser.h>
>> #include <linux/seq_file.h>
>> #include <linux/crc32c.h>
>> +#include <linux/fs_context.h>
>> +#include <linux/fs_parser.h>
>> #include "xattr.h"
>>
>> #define CREATE_TRACE_POINTS
>> @@ -192,41 +194,6 @@ static int erofs_read_superblock(struct super_block *sb)
>> return ret;
>> }
>>
>> -#ifdef CONFIG_EROFS_FS_ZIP
>> -static int erofs_build_cache_strategy(struct super_block *sb,
>> - substring_t *args)
>> -{
>> - struct erofs_sb_info *sbi = EROFS_SB(sb);
>> - const char *cs = match_strdup(args);
>> - int err = 0;
>> -
>> - if (!cs) {
>> - erofs_err(sb, "Not enough memory to store cache strategy");
>> - return -ENOMEM;
>> - }
>> -
>> - if (!strcmp(cs, "disabled")) {
>> - sbi->cache_strategy = EROFS_ZIP_CACHE_DISABLED;
>> - } else if (!strcmp(cs, "readahead")) {
>> - sbi->cache_strategy = EROFS_ZIP_CACHE_READAHEAD;
>> - } else if (!strcmp(cs, "readaround")) {
>> - sbi->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
>> - } else {
>> - erofs_err(sb, "Unrecognized cache strategy \"%s\"", cs);
>> - err = -EINVAL;
>> - }
>> - kfree(cs);
>> - return err;
>> -}
>> -#else
>> -static int erofs_build_cache_strategy(struct super_block *sb,
>> - substring_t *args)
>> -{
>> - erofs_info(sb, "EROFS compression is disabled, so cache strategy is ignored");
>> - return 0;
>> -}
>> -#endif
>> -
>> /* set up default EROFS parameters */
>> static void erofs_default_options(struct erofs_sb_info *sbi)
>> {
>> @@ -251,73 +218,79 @@ enum {
>> Opt_err
>> };
>>
>> -static match_table_t erofs_tokens = {
>> - {Opt_user_xattr, "user_xattr"},
>> - {Opt_nouser_xattr, "nouser_xattr"},
>> - {Opt_acl, "acl"},
>> - {Opt_noacl, "noacl"},
>> - {Opt_cache_strategy, "cache_strategy=%s"},
>> - {Opt_err, NULL}
>> +static const struct fs_parameter_spec erofs_param_specs[] = {
>> + fsparam_flag("user_xattr", Opt_user_xattr),
>> + fsparam_flag("nouser_xattr", Opt_nouser_xattr),
>> + fsparam_flag("acl", Opt_acl),
>> + fsparam_flag("noacl", Opt_noacl),
>> + fsparam_enum("cache_strategy", Opt_cache_strategy),
>> + {}
>> };
>>
>> -static int erofs_parse_options(struct super_block *sb, char *options)
>> -{
>> - substring_t args[MAX_OPT_ARGS];
>> - char *p;
>> - int err;
>> -
>> - if (!options)
>> - return 0;
>> +static const struct fs_parameter_enum erofs_param_enums[] = {
>> + { Opt_cache_strategy, "disabled", EROFS_ZIP_CACHE_DISABLED },
>> + { Opt_cache_strategy, "readahead", EROFS_ZIP_CACHE_READAHEAD},
>> + { Opt_cache_strategy, "readaround", EROFS_ZIP_CACHE_READAROUND},
>> + {}
>> +};
>>
>> - while ((p = strsep(&options, ","))) {
>> - int token;
>> +static const struct fs_parameter_description erofs_fs_parameters = {
>> + .name = "erofs",
>> + .specs = erofs_param_specs,
>> + .enums = erofs_param_enums,
>> +};
>>
>> - if (!*p)
>> - continue;
>> +static int erofs_fc_parse_param(struct fs_context *fc,
>> + struct fs_parameter *param)
>> +{
>> + struct erofs_sb_info *sbi __maybe_unused = fc->s_fs_info;
>> + struct fs_parse_result result;
>> + int opt;
>>
>> - args[0].to = args[0].from = NULL;
>> - token = match_token(p, erofs_tokens, args);
>> + opt = fs_parse(fc, &erofs_fs_parameters, param, &result);
>> + if (opt < 0)
>> + return opt;
>>
>> - switch (token) {
>> + switch (opt) {
>> #ifdef CONFIG_EROFS_FS_XATTR
>> - case Opt_user_xattr:
>> - set_opt(EROFS_SB(sb), XATTR_USER);
>> - break;
>> - case Opt_nouser_xattr:
>> - clear_opt(EROFS_SB(sb), XATTR_USER);
>> - break;
>> + case Opt_user_xattr:
>> + set_opt(sbi, XATTR_USER);
>> + break;
>> + case Opt_nouser_xattr:
>> + clear_opt(sbi, XATTR_USER);
>> + break;
>> #else
>> - case Opt_user_xattr:
>> - erofs_info(sb, "user_xattr options not supported");
>> - break;
>> - case Opt_nouser_xattr:
>> - erofs_info(sb, "nouser_xattr options not supported");
>> - break;
>> + case Opt_user_xattr:
>> + invalf(fc, "erofs: user_xattr options not supported");
>> + break;
>> + case Opt_nouser_xattr:
>> + invalf(fc, "erofs: nouser_xattr options not supported");
>> + break;
>> #endif
>> #ifdef CONFIG_EROFS_FS_POSIX_ACL
>> - case Opt_acl:
>> - set_opt(EROFS_SB(sb), POSIX_ACL);
>> - break;
>> - case Opt_noacl:
>> - clear_opt(EROFS_SB(sb), POSIX_ACL);
>> - break;
>> + case Opt_acl:
>> + set_opt(sbi, POSIX_ACL);
>> + break;
>> + case Opt_noacl:
>> + clear_opt(sbi, POSIX_ACL);
>> + break;
>> +#else
>> + case Opt_acl:
>> + invalf(fc, "erofs: acl options not supported");
>> + break;
>> + case Opt_noacl:
>> + invalf(fc, "erofs: noacl options not supported");
>> + break;
>> +#endif
>> + case Opt_cache_strategy:
>> +#ifdef CONFIG_EROFS_FS_ZIP
>> + sbi->cache_strategy = result.uint_32;
>> #else
>> - case Opt_acl:
>> - erofs_info(sb, "acl options not supported");
>> - break;
>> - case Opt_noacl:
>> - erofs_info(sb, "noacl options not supported");
>> - break;
>> + errorf(fc, "erofs: compression not supported, cache strategy ignored");
>> #endif
>> - case Opt_cache_strategy:
>> - err = erofs_build_cache_strategy(sb, args);
>> - if (err)
>> - return err;
>> - break;
>> - default:
>> - erofs_err(sb, "Unrecognized mount option \"%s\" or missing value", p);
>> - return -EINVAL;
>> - }
>> + break;
>> + default:
>> + return invalf(fc, "erofs: invalid mount option: %s", param->key);
>> }
>> return 0;
>> }
>> @@ -381,7 +354,7 @@ static int erofs_init_managed_cache(struct super_block *sb)
>> static int erofs_init_managed_cache(struct super_block *sb) { return 0; }
>> #endif
>>
>> -static int erofs_fill_super(struct super_block *sb, void *data, int silent)
>> +static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>> {
>> struct inode *inode;
>> struct erofs_sb_info *sbi;
>> @@ -394,11 +367,7 @@ static int erofs_fill_super(struct super_block *sb, void *data, int silent)
>> return -EINVAL;
>> }
>>
>> - sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
>> - if (!sbi)
>> - return -ENOMEM;
>> -
>> - sb->s_fs_info = sbi;
>> + sbi = sb->s_fs_info;
>> err = erofs_read_superblock(sb);
>> if (err)
>> return err;
>> @@ -412,12 +381,6 @@ static int erofs_fill_super(struct super_block *sb, void *data, int silent)
>> #ifdef CONFIG_EROFS_FS_XATTR
>> sb->s_xattr = erofs_xattr_handlers;
>> #endif
>> - /* set erofs default mount options */
>> - erofs_default_options(sbi);
>> -
>> - err = erofs_parse_options(sb, data);
>> - if (err)
>> - return err;
>>
>> if (test_opt(sbi, POSIX_ACL))
>> sb->s_flags |= SB_POSIXACL;
>> @@ -450,15 +413,61 @@ static int erofs_fill_super(struct super_block *sb, void *data, int silent)
>> if (err)
>> return err;
>>
>> - erofs_info(sb, "mounted with opts: %s, root inode @ nid %llu.",
>> - (char *)data, ROOT_NID(sbi));
>> + erofs_info(sb, "mounted with root inode @ nid %llu.", ROOT_NID(sbi));
>> + return 0;
>> +}
>> +
>> +static int erofs_fc_get_tree(struct fs_context *fc)
>> +{
>> + return get_tree_bdev(fc, erofs_fc_fill_super);
>> +}
>> +
>> +static int erofs_fc_reconfigure(struct fs_context *fc)
>> +{
>> + struct super_block *sb = fc->root->d_sb;
>> + struct erofs_sb_info *sbi = EROFS_SB(sb);
>> +
>> + DBG_BUGON(!sb_rdonly(sb));
>> +
>> + if (test_opt(sbi, POSIX_ACL))
>> + fc->sb_flags |= SB_POSIXACL;
>> + else
>> + fc->sb_flags &= ~SB_POSIXACL;
>> +
>> + fc->sb_flags |= SB_RDONLY;
>> return 0;
>> }
>>
>> -static struct dentry *erofs_mount(struct file_system_type *fs_type, int flags,
>> - const char *dev_name, void *data)
>> +static void erofs_fc_free(struct fs_context *fc)
>> {
>> - return mount_bdev(fs_type, flags, dev_name, data, erofs_fill_super);
>> + /*
>> + * sbi stored in fs_context will be cleaned after transferring
>> + * to corresponding superblock on a successful new mount, or
>> + * free it here.
>> + */
>> + kfree(fc->s_fs_info);
>> +}
>> +
>> +static const struct fs_context_operations erofs_context_ops = {
>> + .parse_param = erofs_fc_parse_param,
>> + .get_tree = erofs_fc_get_tree,
>> + .reconfigure = erofs_fc_reconfigure,
>> + .free = erofs_fc_free,
>> +};
>> +
>> +static int erofs_init_fs_context(struct fs_context *fc)
>> +{
>> + struct erofs_sb_info *sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
>> +
>> + if (!sbi)
>> + return -ENOMEM;
>> +
>> + /* set default mount options */
>> + erofs_default_options(sbi);
>> +
>> + fc->s_fs_info = sbi;
>> + fc->ops = &erofs_context_ops;
>> + return 0;
>> }
>>
>> /*
>> @@ -497,7 +506,7 @@ static void erofs_put_super(struct super_block *sb)
>> static struct file_system_type erofs_fs_type = {
>> .owner = THIS_MODULE,
>> .name = "erofs",
>> - .mount = erofs_mount,
>> + .init_fs_context = erofs_init_fs_context,
>> .kill_sb = erofs_kill_sb,
>> .fs_flags = FS_REQUIRES_DEV,
>> };
>> @@ -603,36 +612,12 @@ static int erofs_show_options(struct seq_file *seq, struct dentry *root)
>> return 0;
>> }
>>
>> -static int erofs_remount(struct super_block *sb, int *flags, char *data)
>> -{
>> - struct erofs_sb_info *sbi = EROFS_SB(sb);
>> - unsigned int org_mnt_opt = sbi->mount_opt;
>> - int err;
>> -
>> - DBG_BUGON(!sb_rdonly(sb));
>> - err = erofs_parse_options(sb, data);
>> - if (err)
>> - goto out;
>> -
>> - if (test_opt(sbi, POSIX_ACL))
>> - sb->s_flags |= SB_POSIXACL;
>> - else
>> - sb->s_flags &= ~SB_POSIXACL;
>> -
>> - *flags |= SB_RDONLY;
>> - return 0;
>> -out:
>> - sbi->mount_opt = org_mnt_opt;
>> - return err;
>> -}
>> -
>> const struct super_operations erofs_sops = {
>> .put_super = erofs_put_super,
>> .alloc_inode = erofs_alloc_inode,
>> .free_inode = erofs_free_inode,
>> .statfs = erofs_statfs,
>> .show_options = erofs_show_options,
>> - .remount_fs = erofs_remount,
>> };
>>
>> module_init(erofs_module_init);
>> --
>> 2.18.0.rc1
>>
> .
>

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