在 2022/9/9 16:42, JeffleXu 写道:
On 9/2/22 6:53 PM, Jia Zhu wrote:A new fscache-based shared domain mode is going to be introduced for erofs. In which case, same data blobs in same domain will be shared and reused to reduce on-disk space usage. As the first step, we use pseudo mnt to manage and maintain domain's lifecycle. The implementation of sharing blobs will be introduced in subsequent patches. Signed-off-by: Jia Zhu <zhujia.zj@xxxxxxxxxxxxx> --- fs/erofs/fscache.c | 95 ++++++++++++++++++++++++++++++++++++++++++++- fs/erofs/internal.h | 18 ++++++++- fs/erofs/super.c | 51 ++++++++++++++++++------ 3 files changed, 149 insertions(+), 15 deletions(-) diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c index 8e01d89c3319..439dd3cc096a 100644 --- a/fs/erofs/fscache.c +++ b/fs/erofs/fscache.c @@ -1,10 +1,15 @@ // SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright (C) 2022, Alibaba Cloud + * Copyright (C) 2022, Bytedance Inc. All rights reserved. */ #include <linux/fscache.h> #include "internal.h"+static DEFINE_MUTEX(erofs_domain_list_lock);+static LIST_HEAD(erofs_domain_list); +static struct vfsmount *erofs_pseudo_mnt; + static struct netfs_io_request *erofs_fscache_alloc_request(struct address_space *mapping, loff_t start, size_t len) { @@ -417,6 +422,87 @@ const struct address_space_operations erofs_fscache_access_aops = { .readahead = erofs_fscache_readahead, };+static void erofs_fscache_domain_get(struct erofs_domain *domain)+{ + if (!domain) + return; + refcount_inc(&domain->ref); +}
Hi Jingbo, Thanks for your careful review.
It seems that the input @domain can not be NULL, and thus the NULL check is not needed.
I will remove it in next version.
Besides how about:
struct erofs_domain *domain erofs_fscache_domain_get(struct erofs_domain
*domain)
{
refcount_inc(&domain->ref);
return domain;
}
Thanks for the suggestion, I will apply it.
+ +static void erofs_fscache_domain_put(struct erofs_domain *domain) +{ + if (!domain) + return; + if (refcount_dec_and_test(&domain->ref)) { + fscache_relinquish_volume(domain->volume, NULL, false); + mutex_lock(&erofs_domain_list_lock); + list_del(&domain->list); + mutex_unlock(&erofs_domain_list_lock); + kfree(domain->domain_id); + kfree(domain); + } +} + +static int erofs_fscache_init_domain(struct super_block *sb) +{ + int err; + struct erofs_domain *domain; + struct erofs_sb_info *sbi = EROFS_SB(sb); + + domain = kzalloc(sizeof(struct erofs_domain), GFP_KERNEL); + if (!domain) + return -ENOMEM; + + domain->domain_id = kstrdup(sbi->opt.domain_id, GFP_KERNEL); + if (!domain->domain_id) { + kfree(domain); + return -ENOMEM; + } + sbi->domain = domain; + if (!erofs_pseudo_mnt) { + erofs_pseudo_mnt = kern_mount(&erofs_fs_type); + if (IS_ERR(erofs_pseudo_mnt)) { + err = PTR_ERR(erofs_pseudo_mnt); + goto out; + } + } + err = erofs_fscache_register_fs(sb); + if (err) + goto out; + + domain->volume = sbi->volume; + refcount_set(&domain->ref, 1); + mutex_init(&domain->mutex); + list_add(&domain->list, &erofs_domain_list); + return 0; +out: + kfree(domain->domain_id); + kfree(domain); + sbi->domain = NULL; + return err; +} + +int erofs_fscache_register_domain(struct super_block *sb) +{ + int err; + struct erofs_domain *domain; + struct erofs_sb_info *sbi = EROFS_SB(sb); + + mutex_lock(&erofs_domain_list_lock); + list_for_each_entry(domain, &erofs_domain_list, list) { + if (!strcmp(domain->domain_id, sbi->opt.domain_id)) { + erofs_fscache_domain_get(domain); + sbi->domain = domain;sbi->domain = erofs_fscache_domain_get(domain);+ sbi->volume = domain->volume; + mutex_unlock(&erofs_domain_list_lock); + return 0; + } + } + err = erofs_fscache_init_domain(sb); + mutex_unlock(&erofs_domain_list_lock); + return err; +} + int erofs_fscache_register_cookie(struct super_block *sb, struct erofs_fscache **fscache, char *name, bool need_inode) @@ -495,7 +581,8 @@ int erofs_fscache_register_fs(struct super_block *sb) char *name; int ret = 0;- name = kasprintf(GFP_KERNEL, "erofs,%s", sbi->opt.fsid);+ name = kasprintf(GFP_KERNEL, "erofs,%s", + sbi->domain ? sbi->domain->domain_id : sbi->opt.fsid);Do we also need to encode the cookie name in the "<domain_id>,<fsid>" format? This will affect the path of the cache files.
I think even though the cookies have the same name, they belong to different volumes(path). Cookies do not affect each other. Are there other benefits to doing so?
if (!name) return -ENOMEM;@@ -515,6 +602,10 @@ void erofs_fscache_unregister_fs(struct super_block *sb){ struct erofs_sb_info *sbi = EROFS_SB(sb);- fscache_relinquish_volume(sbi->volume, NULL, false);+ if (sbi->domain) + erofs_fscache_domain_put(sbi->domain); + else + fscache_relinquish_volume(sbi->volume, NULL, false); sbi->volume = NULL; + sbi->domain = NULL; } diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h index fe435d077f1a..2790c93ffb83 100644 --- a/fs/erofs/internal.h +++ b/fs/erofs/internal.h @@ -99,6 +99,14 @@ struct erofs_sb_lz4_info { u16 max_pclusterblks; };+struct erofs_domain {+ refcount_t ref; + struct mutex mutex; + struct list_head list; + struct fscache_volume *volume; + char *domain_id; +}; + struct erofs_fscache { struct fscache_cookie *cookie; struct inode *inode; @@ -158,6 +166,7 @@ struct erofs_sb_info { /* fscache support */ struct fscache_volume *volume; struct erofs_fscache *s_fscache; + struct erofs_domain *domain; };#define EROFS_SB(sb) ((struct erofs_sb_info *)(sb)->s_fs_info)@@ -394,6 +403,7 @@ struct page *erofs_grab_cache_page_nowait(struct address_space *mapping, }extern const struct super_operations erofs_sops;+extern struct file_system_type erofs_fs_type;extern const struct address_space_operations erofs_raw_access_aops;extern const struct address_space_operations z_erofs_aops; @@ -610,6 +620,7 @@ static inline int z_erofs_load_lzma_config(struct super_block *sb, #ifdef CONFIG_EROFS_FS_ONDEMAND int erofs_fscache_register_fs(struct super_block *sb); void erofs_fscache_unregister_fs(struct super_block *sb); +int erofs_fscache_register_domain(struct super_block *sb);int erofs_fscache_register_cookie(struct super_block *sb,struct erofs_fscache **fscache, @@ -620,10 +631,15 @@ extern const struct address_space_operations erofs_fscache_access_aops; #else static inline int erofs_fscache_register_fs(struct super_block *sb) { - return 0; + return -EOPNOTSUPP; } static inline void erofs_fscache_unregister_fs(struct super_block *sb) {}+static inline int erofs_fscache_register_domain(const struct super_block *sb)+{ + return -EOPNOTSUPP; +} + static inline int erofs_fscache_register_cookie(struct super_block *sb, struct erofs_fscache **fscache, char *name, bool need_inode) diff --git a/fs/erofs/super.c b/fs/erofs/super.c index d01109069c6b..69de1731f454 100644 --- a/fs/erofs/super.c +++ b/fs/erofs/super.c @@ -688,6 +688,13 @@ static const struct export_operations erofs_export_ops = { .get_parent = erofs_get_parent, };+static int erofs_fc_fill_pseudo_super(struct super_block *sb, struct fs_context *fc)+{ + static const struct tree_descr empty_descr = {""}; + + return simple_fill_super(sb, EROFS_SUPER_MAGIC, &empty_descr); +} + static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc) { struct inode *inode; @@ -715,12 +722,17 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc) sb->s_blocksize = EROFS_BLKSIZ; sb->s_blocksize_bits = LOG_BLOCK_SIZE;- err = erofs_fscache_register_fs(sb);- if (err) - return err; - - err = erofs_fscache_register_cookie(sb, &sbi->s_fscache, - sbi->opt.fsid, true); + if (sbi->opt.domain_id) { + err = erofs_fscache_register_domain(sb); + if (err) + return err; + } else { + err = erofs_fscache_register_fs(sb); + if (err) + return err; + err = erofs_fscache_register_cookie(sb, &sbi->s_fscache, + sbi->opt.fsid, true);We'd better keep only one entry to the fscache related codes. How about moving erofs_fscache_register_cookie(), i.e. registering cookie for bootstrap, into erofs_fscache_register_fs()? Similarly, check the domain_id and call erofs_fscache_register_domain() inside erofs_fscache_register_fs(). Similarly, check domain_id and call erofs_domain_register_cookie() inside erofs_fscache_register_cookie().
Thanks, that looks great, I will revise it in next version.
+ } if (err) return err;@@ -798,8 +810,12 @@ static int erofs_fc_get_tree(struct fs_context *fc){ struct erofs_fs_context *ctx = fc->fs_private;- if (IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND) && ctx->opt.fsid)- return get_tree_nodev(fc, erofs_fc_fill_super); + if (IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND)) { + if (!ctx && fc->sb_flags & SB_KERNMOUNT) + return get_tree_nodev(fc, erofs_fc_fill_pseudo_super); + if (ctx->opt.fsid) + return get_tree_nodev(fc, erofs_fc_fill_super); + }return get_tree_bdev(fc, erofs_fc_fill_super);} @@ -849,6 +865,8 @@ static void erofs_fc_free(struct fs_context *fc) { struct erofs_fs_context *ctx = fc->fs_private;+ if (!ctx)+ return; erofs_free_dev_context(ctx->devs); kfree(ctx->opt.fsid); kfree(ctx->opt.domain_id); @@ -864,8 +882,12 @@ static const struct fs_context_operations erofs_context_ops = {static int erofs_init_fs_context(struct fs_context *fc){ - struct erofs_fs_context *ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); + struct erofs_fs_context *ctx;+ if (fc->sb_flags & SB_KERNMOUNT)+ goto out; + + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); if (!ctx) return -ENOMEM; ctx->devs = kzalloc(sizeof(struct erofs_dev_context), GFP_KERNEL); @@ -878,6 +900,7 @@ static int erofs_init_fs_context(struct fs_context *fc) idr_init(&ctx->devs->tree); init_rwsem(&ctx->devs->rwsem); erofs_default_options(ctx); +out: fc->ops = &erofs_context_ops; return 0; } @@ -892,6 +915,10 @@ static void erofs_kill_sb(struct super_block *sb)WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC); + if (sb->s_flags & SB_KERNMOUNT) {+ kill_litter_super(sb); + return; + } if (erofs_is_fscache_mode(sb)) generic_shutdown_super(sb); else @@ -916,8 +943,8 @@ static void erofs_put_super(struct super_block *sb) { struct erofs_sb_info *const sbi = EROFS_SB(sb);- DBG_BUGON(!sbi);- + if (!sbi) + return; erofs_unregister_sysfs(sb); erofs_shrinker_unregister(sb); #ifdef CONFIG_EROFS_FS_ZIP @@ -927,7 +954,7 @@ static void erofs_put_super(struct super_block *sb) erofs_fscache_unregister_cookie(&sbi->s_fscache); }-static struct file_system_type erofs_fs_type = {+struct file_system_type erofs_fs_type = { .owner = THIS_MODULE, .name = "erofs", .init_fs_context = erofs_init_fs_context,
