[PATCH 0/4] erofs: cleanup for fscache share domain mode

[PATCH 0/4] erofs: cleanup for fscache share domain mode

[Jingbo Xu]

Jingbo Xu (4):
  erofs: remove unused device mapping in meta routine
  erofs: maintain cookies of share domain in self-contained list
  erofs: unify anonymous inodes for blob
  erofs: simplify the name collision checking in share domain mode

 fs/erofs/fscache.c  | 163 +++++++++++++++-----------------------------
 fs/erofs/internal.h |  14 ++--
 fs/erofs/super.c    |   4 +-
 3 files changed, 66 insertions(+), 115 deletions(-)

-- 
2.19.1.6.gb485710b

[PATCH 1/4] erofs: remove unused device mapping in meta routine

[Jingbo Xu]

Currently metadata is always on bootstrap, and thus device mapping is
not needed so far.  Remove the redundant device mapping in the meta
routine.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
---
 fs/erofs/fscache.c | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index 014e20962376..03de4dc99302 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -164,18 +164,8 @@ static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,
 static int erofs_fscache_meta_read_folio(struct file *data, struct folio *folio)
 {
 	int ret;
-	struct super_block *sb = folio_mapping(folio)->host->i_sb;
+	struct erofs_fscache *ctx = folio_mapping(folio)->host->i_private;
 	struct erofs_fscache_request *req;
-	struct erofs_map_dev mdev = {
-		.m_deviceid = 0,
-		.m_pa = folio_pos(folio),
-	};
-
-	ret = erofs_map_dev(sb, &mdev);
-	if (ret) {
-		folio_unlock(folio);
-		return ret;
-	}
 
 	req = erofs_fscache_req_alloc(folio_mapping(folio),
 				folio_pos(folio), folio_size(folio));
@@ -184,8 +174,8 @@ static int erofs_fscache_meta_read_folio(struct file *data, struct folio *folio)
 		return PTR_ERR(req);
 	}
 
-	ret = erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
-				req, mdev.m_pa, folio_size(folio));
+	ret = erofs_fscache_read_folios_async(ctx->cookie, req,
+				folio_pos(folio), folio_size(folio));
 	if (ret)
 		req->error = ret;
 
@@ -469,6 +459,7 @@ struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb,
 		inode->i_size = OFFSET_MAX;
 		inode->i_mapping->a_ops = &erofs_fscache_meta_aops;
 		mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
+		inode->i_private = ctx;
 
 		ctx->inode = inode;
 	}
-- 
2.19.1.6.gb485710b

Re: [External] [PATCH 1/4] erofs: remove unused device mapping in meta routine

[Jia Zhu]

在 2023/2/8 15:16, Jingbo Xu 写道:
> Currently metadata is always on bootstrap, and thus device mapping is
> not needed so far.  Remove the redundant device mapping in the meta
> routine.
> 
> Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>

Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>

> ---
>   fs/erofs/fscache.c | 17 ++++-------------
>   1 file changed, 4 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
> index 014e20962376..03de4dc99302 100644
> --- a/fs/erofs/fscache.c
> +++ b/fs/erofs/fscache.c
> @@ -164,18 +164,8 @@ static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,
>   static int erofs_fscache_meta_read_folio(struct file *data, struct folio *folio)
>   {
>   	int ret;
> -	struct super_block *sb = folio_mapping(folio)->host->i_sb;
> +	struct erofs_fscache *ctx = folio_mapping(folio)->host->i_private;
>   	struct erofs_fscache_request *req;
> -	struct erofs_map_dev mdev = {
> -		.m_deviceid = 0,
> -		.m_pa = folio_pos(folio),
> -	};
> -
> -	ret = erofs_map_dev(sb, &mdev);
> -	if (ret) {
> -		folio_unlock(folio);
> -		return ret;
> -	}
>   
>   	req = erofs_fscache_req_alloc(folio_mapping(folio),
>   				folio_pos(folio), folio_size(folio));
> @@ -184,8 +174,8 @@ static int erofs_fscache_meta_read_folio(struct file *data, struct folio *folio)
>   		return PTR_ERR(req);
>   	}
>   
> -	ret = erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
> -				req, mdev.m_pa, folio_size(folio));
> +	ret = erofs_fscache_read_folios_async(ctx->cookie, req,
> +				folio_pos(folio), folio_size(folio));
>   	if (ret)
>   		req->error = ret;
>   
> @@ -469,6 +459,7 @@ struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb,
>   		inode->i_size = OFFSET_MAX;
>   		inode->i_mapping->a_ops = &erofs_fscache_meta_aops;
>   		mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
> +		inode->i_private = ctx;
>   
>   		ctx->inode = inode;
>   	}

[PATCH 2/4] erofs: maintain cookies of share domain in self-contained list

[Jingbo Xu]

We'd better not touch sb->s_inodes list and inode->i_count directly.
Let's maintain cookies of share domain in a self-contained list in erofs.

Besides, relinquish cookie with the mutext held.  Otherwise if a cookie
is registered when the old cookie with the same name in the same domain
has been removed from the list but not relinquished yet, fscache may
complain "Duplicate cookie detected".

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
---
 fs/erofs/fscache.c  | 48 ++++++++++++++++++++++-----------------------
 fs/erofs/internal.h |  4 ++++
 2 files changed, 27 insertions(+), 25 deletions(-)

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index 03de4dc99302..2f5930e177cc 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -7,8 +7,11 @@
 #include "internal.h"
 
 static DEFINE_MUTEX(erofs_domain_list_lock);
-static DEFINE_MUTEX(erofs_domain_cookies_lock);
 static LIST_HEAD(erofs_domain_list);
+
+static DEFINE_MUTEX(erofs_domain_cookies_lock);
+static LIST_HEAD(erofs_domain_cookies_list);
+
 static struct vfsmount *erofs_pseudo_mnt;
 
 struct erofs_fscache_request {
@@ -318,8 +321,6 @@ const struct address_space_operations erofs_fscache_access_aops = {
 
 static void erofs_fscache_domain_put(struct erofs_domain *domain)
 {
-	if (!domain)
-		return;
 	mutex_lock(&erofs_domain_list_lock);
 	if (refcount_dec_and_test(&domain->ref)) {
 		list_del(&domain->list);
@@ -434,6 +435,8 @@ struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb,
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
 		return ERR_PTR(-ENOMEM);
+	INIT_LIST_HEAD(&ctx->node);
+	refcount_set(&ctx->ref, 1);
 
 	cookie = fscache_acquire_cookie(volume, FSCACHE_ADV_WANT_CACHE_SIZE,
 					name, strlen(name), NULL, 0, 0);
@@ -479,6 +482,7 @@ static void erofs_fscache_relinquish_cookie(struct erofs_fscache *ctx)
 	fscache_unuse_cookie(ctx->cookie, NULL, NULL);
 	fscache_relinquish_cookie(ctx->cookie, false);
 	iput(ctx->inode);
+	iput(ctx->anon_inode);
 	kfree(ctx->name);
 	kfree(ctx);
 }
@@ -511,6 +515,7 @@ struct erofs_fscache *erofs_fscache_domain_init_cookie(struct super_block *sb,
 
 	ctx->domain = domain;
 	ctx->anon_inode = inode;
+	list_add(&ctx->node, &erofs_domain_cookies_list);
 	inode->i_private = ctx;
 	refcount_inc(&domain->ref);
 	return ctx;
@@ -524,29 +529,23 @@ struct erofs_fscache *erofs_domain_register_cookie(struct super_block *sb,
 						   char *name,
 						   unsigned int flags)
 {
-	struct inode *inode;
 	struct erofs_fscache *ctx;
 	struct erofs_domain *domain = EROFS_SB(sb)->domain;
-	struct super_block *psb = erofs_pseudo_mnt->mnt_sb;
 
 	mutex_lock(&erofs_domain_cookies_lock);
-	spin_lock(&psb->s_inode_list_lock);
-	list_for_each_entry(inode, &psb->s_inodes, i_sb_list) {
-		ctx = inode->i_private;
-		if (!ctx || ctx->domain != domain || strcmp(ctx->name, name))
+	list_for_each_entry(ctx, &erofs_domain_cookies_list, node) {
+		if (ctx->domain != domain || strcmp(ctx->name, name))
 			continue;
 		if (!(flags & EROFS_REG_COOKIE_NEED_NOEXIST)) {
-			igrab(inode);
+			refcount_inc(&ctx->ref);
 		} else {
 			erofs_err(sb, "%s already exists in domain %s", name,
 				  domain->domain_id);
 			ctx = ERR_PTR(-EEXIST);
 		}
-		spin_unlock(&psb->s_inode_list_lock);
 		mutex_unlock(&erofs_domain_cookies_lock);
 		return ctx;
 	}
-	spin_unlock(&psb->s_inode_list_lock);
 	ctx = erofs_fscache_domain_init_cookie(sb, name, flags);
 	mutex_unlock(&erofs_domain_cookies_lock);
 	return ctx;
@@ -563,23 +562,22 @@ struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
 
 void erofs_fscache_unregister_cookie(struct erofs_fscache *ctx)
 {
-	bool drop;
-	struct erofs_domain *domain;
+	struct erofs_domain *domain = NULL;
 
 	if (!ctx)
 		return;
-	domain = ctx->domain;
-	if (domain) {
-		mutex_lock(&erofs_domain_cookies_lock);
-		drop = atomic_read(&ctx->anon_inode->i_count) == 1;
-		iput(ctx->anon_inode);
-		mutex_unlock(&erofs_domain_cookies_lock);
-		if (!drop)
-			return;
-	}
+	if (!ctx->domain)
+		return erofs_fscache_relinquish_cookie(ctx);
 
-	erofs_fscache_relinquish_cookie(ctx);
-	erofs_fscache_domain_put(domain);
+	mutex_lock(&erofs_domain_cookies_lock);
+	if (refcount_dec_and_test(&ctx->ref)) {
+		domain = ctx->domain;
+		list_del(&ctx->node);
+		erofs_fscache_relinquish_cookie(ctx);
+	}
+	mutex_unlock(&erofs_domain_cookies_lock);
+	if (domain)
+		erofs_fscache_domain_put(domain);
 }
 
 int erofs_fscache_register_fs(struct super_block *sb)
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 48a2f33de15a..8358cf5f731e 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -109,7 +109,11 @@ struct erofs_fscache {
 	struct fscache_cookie *cookie;
 	struct inode *inode;
 	struct inode *anon_inode;
+
+	/* used for share domain mode */
 	struct erofs_domain *domain;
+	struct list_head node;
+	refcount_t ref;
 	char *name;
 };
 
-- 
2.19.1.6.gb485710b

Re: [External] [PATCH 2/4] erofs: maintain cookies of share domain in self-contained list

[Jia Zhu]

在 2023/2/8 15:16, Jingbo Xu 写道:
> We'd better not touch sb->s_inodes list and inode->i_count directly.
> Let's maintain cookies of share domain in a self-contained list in erofs.
> 
> Besides, relinquish cookie with the mutext held.  Otherwise if a cookie
                                       ~~~~~~
                                       mutex
Besides this, LGTM.

Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>

> is registered when the old cookie with the same name in the same domain
> has been removed from the list but not relinquished yet, fscache may
> complain "Duplicate cookie detected".
> 
> Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
> ---
>   fs/erofs/fscache.c  | 48 ++++++++++++++++++++++-----------------------
>   fs/erofs/internal.h |  4 ++++
>   2 files changed, 27 insertions(+), 25 deletions(-)
> 
> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
> index 03de4dc99302..2f5930e177cc 100644
> --- a/fs/erofs/fscache.c
> +++ b/fs/erofs/fscache.c
> @@ -7,8 +7,11 @@
>   #include "internal.h"
>   
>   static DEFINE_MUTEX(erofs_domain_list_lock);
> -static DEFINE_MUTEX(erofs_domain_cookies_lock);
>   static LIST_HEAD(erofs_domain_list);
> +
> +static DEFINE_MUTEX(erofs_domain_cookies_lock);
> +static LIST_HEAD(erofs_domain_cookies_list);
> +
>   static struct vfsmount *erofs_pseudo_mnt;
>   
>   struct erofs_fscache_request {
> @@ -318,8 +321,6 @@ const struct address_space_operations erofs_fscache_access_aops = {
>   
>   static void erofs_fscache_domain_put(struct erofs_domain *domain)
>   {
> -	if (!domain)
> -		return;
>   	mutex_lock(&erofs_domain_list_lock);
>   	if (refcount_dec_and_test(&domain->ref)) {
>   		list_del(&domain->list);
> @@ -434,6 +435,8 @@ struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb,
>   	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
>   	if (!ctx)
>   		return ERR_PTR(-ENOMEM);
> +	INIT_LIST_HEAD(&ctx->node);
> +	refcount_set(&ctx->ref, 1);
>   
>   	cookie = fscache_acquire_cookie(volume, FSCACHE_ADV_WANT_CACHE_SIZE,
>   					name, strlen(name), NULL, 0, 0);
> @@ -479,6 +482,7 @@ static void erofs_fscache_relinquish_cookie(struct erofs_fscache *ctx)
>   	fscache_unuse_cookie(ctx->cookie, NULL, NULL);
>   	fscache_relinquish_cookie(ctx->cookie, false);
>   	iput(ctx->inode);
> +	iput(ctx->anon_inode);
>   	kfree(ctx->name);
>   	kfree(ctx);
>   }
> @@ -511,6 +515,7 @@ struct erofs_fscache *erofs_fscache_domain_init_cookie(struct super_block *sb,
>   
>   	ctx->domain = domain;
>   	ctx->anon_inode = inode;
> +	list_add(&ctx->node, &erofs_domain_cookies_list);
>   	inode->i_private = ctx;
>   	refcount_inc(&domain->ref);
>   	return ctx;
> @@ -524,29 +529,23 @@ struct erofs_fscache *erofs_domain_register_cookie(struct super_block *sb,
>   						   char *name,
>   						   unsigned int flags)
>   {
> -	struct inode *inode;
>   	struct erofs_fscache *ctx;
>   	struct erofs_domain *domain = EROFS_SB(sb)->domain;
> -	struct super_block *psb = erofs_pseudo_mnt->mnt_sb;
>   
>   	mutex_lock(&erofs_domain_cookies_lock);
> -	spin_lock(&psb->s_inode_list_lock);
> -	list_for_each_entry(inode, &psb->s_inodes, i_sb_list) {
> -		ctx = inode->i_private;
> -		if (!ctx || ctx->domain != domain || strcmp(ctx->name, name))
> +	list_for_each_entry(ctx, &erofs_domain_cookies_list, node) {
> +		if (ctx->domain != domain || strcmp(ctx->name, name))
>   			continue;
>   		if (!(flags & EROFS_REG_COOKIE_NEED_NOEXIST)) {
> -			igrab(inode);
> +			refcount_inc(&ctx->ref);
>   		} else {
>   			erofs_err(sb, "%s already exists in domain %s", name,
>   				  domain->domain_id);
>   			ctx = ERR_PTR(-EEXIST);
>   		}
> -		spin_unlock(&psb->s_inode_list_lock);
>   		mutex_unlock(&erofs_domain_cookies_lock);
>   		return ctx;
>   	}
> -	spin_unlock(&psb->s_inode_list_lock);
>   	ctx = erofs_fscache_domain_init_cookie(sb, name, flags);
>   	mutex_unlock(&erofs_domain_cookies_lock);
>   	return ctx;
> @@ -563,23 +562,22 @@ struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
>   
>   void erofs_fscache_unregister_cookie(struct erofs_fscache *ctx)
>   {
> -	bool drop;
> -	struct erofs_domain *domain;
> +	struct erofs_domain *domain = NULL;
>   
>   	if (!ctx)
>   		return;
> -	domain = ctx->domain;
> -	if (domain) {
> -		mutex_lock(&erofs_domain_cookies_lock);
> -		drop = atomic_read(&ctx->anon_inode->i_count) == 1;
> -		iput(ctx->anon_inode);
> -		mutex_unlock(&erofs_domain_cookies_lock);
> -		if (!drop)
> -			return;
> -	}
> +	if (!ctx->domain)
> +		return erofs_fscache_relinquish_cookie(ctx);
>   
> -	erofs_fscache_relinquish_cookie(ctx);
> -	erofs_fscache_domain_put(domain);
> +	mutex_lock(&erofs_domain_cookies_lock);
> +	if (refcount_dec_and_test(&ctx->ref)) {
> +		domain = ctx->domain;
> +		list_del(&ctx->node);
> +		erofs_fscache_relinquish_cookie(ctx);
> +	}
> +	mutex_unlock(&erofs_domain_cookies_lock);
> +	if (domain)
> +		erofs_fscache_domain_put(domain);
>   }
>   
>   int erofs_fscache_register_fs(struct super_block *sb)
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 48a2f33de15a..8358cf5f731e 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -109,7 +109,11 @@ struct erofs_fscache {
>   	struct fscache_cookie *cookie;
>   	struct inode *inode;
>   	struct inode *anon_inode;
> +
> +	/* used for share domain mode */
>   	struct erofs_domain *domain;
> +	struct list_head node;
> +	refcount_t ref;
>   	char *name;
>   };
>   

[PATCH 3/4] erofs: unify anonymous inodes for blob

[Jingbo Xu]

Currently there're two anonymous inodes (inode and anon_inode in struct
erofs_fscache) for each blob.  The former was introduced as the
address_space of page cache for bootstrap.

The latter was initially introduced as both the address_space of page
cache and also a sentinel in the shared domain.  Since now the management
of cookies in share domain has been decoupled with the anonymous inode,
there's no need to maintain an extra anonymous inode.  Let's unify these
two anonymous inodes.

Besides, in non-share-domain mode only bootstrap will allocate anonymous
inode.  To simplify the implementation, always allocate anonymous inode
for both bootstrap and data blobs.  Similarly release anonymous inodes
for data blobs when .put_super() is called, or we'll get "VFS: Busy
inodes after unmount." warning.

Also remove the redundant set_nlink() when initializing the anonymous
inode, since i_nlink has already been initialized to 1 when the inode
gets allocated.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
---
 fs/erofs/fscache.c  | 70 ++++++++++++++++-----------------------------
 fs/erofs/internal.h |  6 ++--
 fs/erofs/super.c    |  2 ++
 3 files changed, 28 insertions(+), 50 deletions(-)

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index 2f5930e177cc..8353a5fe8c71 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -424,12 +424,12 @@ static int erofs_fscache_register_domain(struct super_block *sb)
 
 static
 struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb,
-						   char *name,
-						   unsigned int flags)
+					struct super_block *isb, char *name)
 {
 	struct fscache_volume *volume = EROFS_SB(sb)->volume;
 	struct erofs_fscache *ctx;
 	struct fscache_cookie *cookie;
+	struct inode *inode;
 	int ret;
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
@@ -445,33 +445,27 @@ struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb,
 		ret = -EINVAL;
 		goto err;
 	}
-
 	fscache_use_cookie(cookie, false);
-	ctx->cookie = cookie;
-
-	if (flags & EROFS_REG_COOKIE_NEED_INODE) {
-		struct inode *const inode = new_inode(sb);
-
-		if (!inode) {
-			erofs_err(sb, "failed to get anon inode for %s", name);
-			ret = -ENOMEM;
-			goto err_cookie;
-		}
-
-		set_nlink(inode, 1);
-		inode->i_size = OFFSET_MAX;
-		inode->i_mapping->a_ops = &erofs_fscache_meta_aops;
-		mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
-		inode->i_private = ctx;
 
-		ctx->inode = inode;
+	inode = new_inode(isb);
+	if (!inode) {
+		erofs_err(sb, "failed to get anon inode for %s", name);
+		ret = -ENOMEM;
+		goto err_cookie;
 	}
 
+	inode->i_size = OFFSET_MAX;
+	inode->i_mapping->a_ops = &erofs_fscache_meta_aops;
+	mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
+	inode->i_private = ctx;
+
+	ctx->cookie = cookie;
+	ctx->inode = inode;
 	return ctx;
 
 err_cookie:
-	fscache_unuse_cookie(ctx->cookie, NULL, NULL);
-	fscache_relinquish_cookie(ctx->cookie, false);
+	fscache_unuse_cookie(cookie, NULL, NULL);
+	fscache_relinquish_cookie(cookie, false);
 err:
 	kfree(ctx);
 	return ERR_PTR(ret);
@@ -482,46 +476,31 @@ static void erofs_fscache_relinquish_cookie(struct erofs_fscache *ctx)
 	fscache_unuse_cookie(ctx->cookie, NULL, NULL);
 	fscache_relinquish_cookie(ctx->cookie, false);
 	iput(ctx->inode);
-	iput(ctx->anon_inode);
 	kfree(ctx->name);
 	kfree(ctx);
 }
 
 static
 struct erofs_fscache *erofs_fscache_domain_init_cookie(struct super_block *sb,
-						       char *name,
-						       unsigned int flags)
+						       char *name)
 {
-	int err;
-	struct inode *inode;
 	struct erofs_fscache *ctx;
 	struct erofs_domain *domain = EROFS_SB(sb)->domain;
 
-	ctx = erofs_fscache_acquire_cookie(sb, name, flags);
+	ctx = erofs_fscache_acquire_cookie(sb, erofs_pseudo_mnt->mnt_sb, name);
 	if (IS_ERR(ctx))
 		return ctx;
 
 	ctx->name = kstrdup(name, GFP_KERNEL);
 	if (!ctx->name) {
-		err = -ENOMEM;
-		goto out;
-	}
-
-	inode = new_inode(erofs_pseudo_mnt->mnt_sb);
-	if (!inode) {
-		err = -ENOMEM;
-		goto out;
+		erofs_fscache_relinquish_cookie(ctx);
+		return ERR_PTR(-ENOMEM);
 	}
 
+	refcount_inc(&domain->ref);
 	ctx->domain = domain;
-	ctx->anon_inode = inode;
 	list_add(&ctx->node, &erofs_domain_cookies_list);
-	inode->i_private = ctx;
-	refcount_inc(&domain->ref);
 	return ctx;
-out:
-	erofs_fscache_relinquish_cookie(ctx);
-	return ERR_PTR(err);
 }
 
 static
@@ -546,7 +525,7 @@ struct erofs_fscache *erofs_domain_register_cookie(struct super_block *sb,
 		mutex_unlock(&erofs_domain_cookies_lock);
 		return ctx;
 	}
-	ctx = erofs_fscache_domain_init_cookie(sb, name, flags);
+	ctx = erofs_fscache_domain_init_cookie(sb, name);
 	mutex_unlock(&erofs_domain_cookies_lock);
 	return ctx;
 }
@@ -557,7 +536,7 @@ struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
 {
 	if (EROFS_SB(sb)->domain_id)
 		return erofs_domain_register_cookie(sb, name, flags);
-	return erofs_fscache_acquire_cookie(sb, name, flags);
+	return erofs_fscache_acquire_cookie(sb, sb, name);
 }
 
 void erofs_fscache_unregister_cookie(struct erofs_fscache *ctx)
@@ -585,7 +564,7 @@ int erofs_fscache_register_fs(struct super_block *sb)
 	int ret;
 	struct erofs_sb_info *sbi = EROFS_SB(sb);
 	struct erofs_fscache *fscache;
-	unsigned int flags;
+	unsigned int flags = 0;
 
 	if (sbi->domain_id)
 		ret = erofs_fscache_register_domain(sb);
@@ -604,7 +583,6 @@ int erofs_fscache_register_fs(struct super_block *sb)
 	 *
 	 * Acquired domain/volume will be relinquished in kill_sb() on error.
 	 */
-	flags = EROFS_REG_COOKIE_NEED_INODE;
 	if (sbi->domain_id)
 		flags |= EROFS_REG_COOKIE_NEED_NOEXIST;
 	fscache = erofs_fscache_register_cookie(sb, sbi->fsid, flags);
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 8358cf5f731e..125e4aa8d295 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -107,8 +107,7 @@ struct erofs_domain {
 
 struct erofs_fscache {
 	struct fscache_cookie *cookie;
-	struct inode *inode;
-	struct inode *anon_inode;
+	struct inode *inode;	/* anonymous indoe for the blob */
 
 	/* used for share domain mode */
 	struct erofs_domain *domain;
@@ -450,8 +449,7 @@ extern const struct file_operations erofs_dir_fops;
 extern const struct iomap_ops z_erofs_iomap_report_ops;
 
 /* flags for erofs_fscache_register_cookie() */
-#define EROFS_REG_COOKIE_NEED_INODE	1
-#define EROFS_REG_COOKIE_NEED_NOEXIST	2
+#define EROFS_REG_COOKIE_NEED_NOEXIST	1
 
 void erofs_unmap_metabuf(struct erofs_buf *buf);
 void erofs_put_metabuf(struct erofs_buf *buf);
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 715efa94eed4..19b1ae79cec4 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -968,6 +968,8 @@ static void erofs_put_super(struct super_block *sb)
 	iput(sbi->packed_inode);
 	sbi->packed_inode = NULL;
 #endif
+	erofs_free_dev_context(sbi->devs);
+	sbi->devs = NULL;
 	erofs_fscache_unregister_fs(sb);
 }
 
-- 
2.19.1.6.gb485710b

Re: [External] [PATCH 3/4] erofs: unify anonymous inodes for blob

[Jia Zhu]

在 2023/2/8 15:16, Jingbo Xu 写道:
> Currently there're two anonymous inodes (inode and anon_inode in struct
> erofs_fscache) for each blob.  The former was introduced as the
> address_space of page cache for bootstrap.
> 
> The latter was initially introduced as both the address_space of page
> cache and also a sentinel in the shared domain.  Since now the management
> of cookies in share domain has been decoupled with the anonymous inode,
> there's no need to maintain an extra anonymous inode.  Let's unify these
> two anonymous inodes.
> 
> Besides, in non-share-domain mode only bootstrap will allocate anonymous
> inode.  To simplify the implementation, always allocate anonymous inode
> for both bootstrap and data blobs.  Similarly release anonymous inodes
> for data blobs when .put_super() is called, or we'll get "VFS: Busy
> inodes after unmount." warning.
> 
> Also remove the redundant set_nlink() when initializing the anonymous
> inode, since i_nlink has already been initialized to 1 when the inode
> gets allocated.
> 
> Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
> ---
>   fs/erofs/fscache.c  | 70 ++++++++++++++++-----------------------------
>   fs/erofs/internal.h |  6 ++--
>   fs/erofs/super.c    |  2 ++
>   3 files changed, 28 insertions(+), 50 deletions(-)
> 
> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
> index 2f5930e177cc..8353a5fe8c71 100644
> --- a/fs/erofs/fscache.c
> +++ b/fs/erofs/fscache.c
> @@ -424,12 +424,12 @@ static int erofs_fscache_register_domain(struct super_block *sb)
>   
>   static
>   struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb,
> -						   char *name,
> -						   unsigned int flags)
> +					struct super_block *isb, char *name)
>   {
>   	struct fscache_volume *volume = EROFS_SB(sb)->volume;
>   	struct erofs_fscache *ctx;
>   	struct fscache_cookie *cookie;
> +	struct inode *inode;
>   	int ret;
>   
>   	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> @@ -445,33 +445,27 @@ struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb,
>   		ret = -EINVAL;
>   		goto err;
>   	}
> -
>   	fscache_use_cookie(cookie, false);
> -	ctx->cookie = cookie;
> -
> -	if (flags & EROFS_REG_COOKIE_NEED_INODE) {
> -		struct inode *const inode = new_inode(sb);
> -
> -		if (!inode) {
> -			erofs_err(sb, "failed to get anon inode for %s", name);
> -			ret = -ENOMEM;
> -			goto err_cookie;
> -		}
> -
> -		set_nlink(inode, 1);
> -		inode->i_size = OFFSET_MAX;
> -		inode->i_mapping->a_ops = &erofs_fscache_meta_aops;
> -		mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
> -		inode->i_private = ctx;
>   
> -		ctx->inode = inode;
> +	inode = new_inode(isb);
> +	if (!inode) {
> +		erofs_err(sb, "failed to get anon inode for %s", name);
> +		ret = -ENOMEM;
> +		goto err_cookie;
>   	}
>   
> +	inode->i_size = OFFSET_MAX;
> +	inode->i_mapping->a_ops = &erofs_fscache_meta_aops;
> +	mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
> +	inode->i_private = ctx;
> +
> +	ctx->cookie = cookie;
> +	ctx->inode = inode;
>   	return ctx;
>   
>   err_cookie:
> -	fscache_unuse_cookie(ctx->cookie, NULL, NULL);
> -	fscache_relinquish_cookie(ctx->cookie, false);
> +	fscache_unuse_cookie(cookie, NULL, NULL);
> +	fscache_relinquish_cookie(cookie, false);
>   err:
>   	kfree(ctx);
>   	return ERR_PTR(ret);
> @@ -482,46 +476,31 @@ static void erofs_fscache_relinquish_cookie(struct erofs_fscache *ctx)
>   	fscache_unuse_cookie(ctx->cookie, NULL, NULL);
>   	fscache_relinquish_cookie(ctx->cookie, false);
>   	iput(ctx->inode);
> -	iput(ctx->anon_inode);
>   	kfree(ctx->name);
>   	kfree(ctx);
>   }
>   
>   static
>   struct erofs_fscache *erofs_fscache_domain_init_cookie(struct super_block *sb,
> -						       char *name,
> -						       unsigned int flags)
> +						       char *name)
>   {
> -	int err;
> -	struct inode *inode;
>   	struct erofs_fscache *ctx;
>   	struct erofs_domain *domain = EROFS_SB(sb)->domain;
>   
> -	ctx = erofs_fscache_acquire_cookie(sb, name, flags);
> +	ctx = erofs_fscache_acquire_cookie(sb, erofs_pseudo_mnt->mnt_sb, name);
>   	if (IS_ERR(ctx))
>   		return ctx;
>   
>   	ctx->name = kstrdup(name, GFP_KERNEL);
>   	if (!ctx->name) {
> -		err = -ENOMEM;
> -		goto out;
> -	}
> -
> -	inode = new_inode(erofs_pseudo_mnt->mnt_sb);
> -	if (!inode) {
> -		err = -ENOMEM;
> -		goto out;
> +		erofs_fscache_relinquish_cookie(ctx);
> +		return ERR_PTR(-ENOMEM);
>   	}
>   
> +	refcount_inc(&domain->ref);
>   	ctx->domain = domain;
> -	ctx->anon_inode = inode;
>   	list_add(&ctx->node, &erofs_domain_cookies_list);
> -	inode->i_private = ctx;
> -	refcount_inc(&domain->ref);
>   	return ctx;
> -out:
> -	erofs_fscache_relinquish_cookie(ctx);
> -	return ERR_PTR(err);
>   }
>   
>   static
> @@ -546,7 +525,7 @@ struct erofs_fscache *erofs_domain_register_cookie(struct super_block *sb,
>   		mutex_unlock(&erofs_domain_cookies_lock);
>   		return ctx;
>   	}
> -	ctx = erofs_fscache_domain_init_cookie(sb, name, flags);
> +	ctx = erofs_fscache_domain_init_cookie(sb, name);
>   	mutex_unlock(&erofs_domain_cookies_lock);
>   	return ctx;
>   }
> @@ -557,7 +536,7 @@ struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
>   {
>   	if (EROFS_SB(sb)->domain_id)
>   		return erofs_domain_register_cookie(sb, name, flags);
> -	return erofs_fscache_acquire_cookie(sb, name, flags);
> +	return erofs_fscache_acquire_cookie(sb, sb, name);

How about using <sb, flags> to indicate shared/non-shared domain
mode?
Besides, LGTM.

Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>

>   }
>   
>   void erofs_fscache_unregister_cookie(struct erofs_fscache *ctx)
> @@ -585,7 +564,7 @@ int erofs_fscache_register_fs(struct super_block *sb)
>   	int ret;
>   	struct erofs_sb_info *sbi = EROFS_SB(sb);
>   	struct erofs_fscache *fscache;
> -	unsigned int flags;
> +	unsigned int flags = 0;
>   
>   	if (sbi->domain_id)
>   		ret = erofs_fscache_register_domain(sb);
> @@ -604,7 +583,6 @@ int erofs_fscache_register_fs(struct super_block *sb)
>   	 *
>   	 * Acquired domain/volume will be relinquished in kill_sb() on error.
>   	 */
> -	flags = EROFS_REG_COOKIE_NEED_INODE;
>   	if (sbi->domain_id)
>   		flags |= EROFS_REG_COOKIE_NEED_NOEXIST;
>   	fscache = erofs_fscache_register_cookie(sb, sbi->fsid, flags);
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 8358cf5f731e..125e4aa8d295 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -107,8 +107,7 @@ struct erofs_domain {
>   
>   struct erofs_fscache {
>   	struct fscache_cookie *cookie;
> -	struct inode *inode;
> -	struct inode *anon_inode;
> +	struct inode *inode;	/* anonymous indoe for the blob */
>   
>   	/* used for share domain mode */
>   	struct erofs_domain *domain;
> @@ -450,8 +449,7 @@ extern const struct file_operations erofs_dir_fops;
>   extern const struct iomap_ops z_erofs_iomap_report_ops;
>   
>   /* flags for erofs_fscache_register_cookie() */
> -#define EROFS_REG_COOKIE_NEED_INODE	1
> -#define EROFS_REG_COOKIE_NEED_NOEXIST	2
> +#define EROFS_REG_COOKIE_NEED_NOEXIST	1
>   
>   void erofs_unmap_metabuf(struct erofs_buf *buf);
>   void erofs_put_metabuf(struct erofs_buf *buf);
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index 715efa94eed4..19b1ae79cec4 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -968,6 +968,8 @@ static void erofs_put_super(struct super_block *sb)
>   	iput(sbi->packed_inode);
>   	sbi->packed_inode = NULL;
>   #endif
> +	erofs_free_dev_context(sbi->devs);
> +	sbi->devs = NULL;
>   	erofs_fscache_unregister_fs(sb);
>   }
>   

[PATCH 4/4] erofs: simplify the name collision checking in share domain mode

[Jingbo Xu]

When share domain is enabled, data blobs can be shared among filesystem
instances in the same domain for data deduplication, while bootstrap
blobs are always dedicated to the corresponding filesystem instance, and
have no need to be shared.

In the initial implementation of share domain (commit 7d41963759fe
("erofs: Support sharing cookies in the same domain")), bootstrap blobs
are also in the share domain, and thus can be referenced by the
following filesystem instances.  In this case, mounting twice with the
same fsid and domain_id will trigger warning in sysfs.  Commit
27f2a2dcc626 ("erofs: check the uniqueness of fsid in shared domain in
advance") fixes this by introducing the name collision checking.

This patch attempts to fix the above issue in another simpler way.
Since the bootstrap blobs have no need to be shared, move them out of
the share domain, so that one bootstrap blob can not be referenced by
other filesystem instances.  Attempt to mount twice with the same fsid
and domain_id will fail with info of duplicate cookies, which is
consistent with the behavior in non-share-domain mode.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
---
 fs/erofs/fscache.c  | 36 ++++++++----------------------------
 fs/erofs/internal.h |  4 ++--
 fs/erofs/super.c    |  2 +-
 3 files changed, 11 insertions(+), 31 deletions(-)

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index 8353a5fe8c71..8da6e05e9d23 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -505,25 +505,18 @@ struct erofs_fscache *erofs_fscache_domain_init_cookie(struct super_block *sb,
 
 static
 struct erofs_fscache *erofs_domain_register_cookie(struct super_block *sb,
-						   char *name,
-						   unsigned int flags)
+						   char *name)
 {
 	struct erofs_fscache *ctx;
 	struct erofs_domain *domain = EROFS_SB(sb)->domain;
 
 	mutex_lock(&erofs_domain_cookies_lock);
 	list_for_each_entry(ctx, &erofs_domain_cookies_list, node) {
-		if (ctx->domain != domain || strcmp(ctx->name, name))
-			continue;
-		if (!(flags & EROFS_REG_COOKIE_NEED_NOEXIST)) {
+		if (ctx->domain == domain && !strcmp(ctx->name, name)) {
 			refcount_inc(&ctx->ref);
-		} else {
-			erofs_err(sb, "%s already exists in domain %s", name,
-				  domain->domain_id);
-			ctx = ERR_PTR(-EEXIST);
+			mutex_unlock(&erofs_domain_cookies_lock);
+			return ctx;
 		}
-		mutex_unlock(&erofs_domain_cookies_lock);
-		return ctx;
 	}
 	ctx = erofs_fscache_domain_init_cookie(sb, name);
 	mutex_unlock(&erofs_domain_cookies_lock);
@@ -531,11 +524,10 @@ struct erofs_fscache *erofs_domain_register_cookie(struct super_block *sb,
 }
 
 struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
-						    char *name,
-						    unsigned int flags)
+						    char *name)
 {
 	if (EROFS_SB(sb)->domain_id)
-		return erofs_domain_register_cookie(sb, name, flags);
+		return erofs_domain_register_cookie(sb, name);
 	return erofs_fscache_acquire_cookie(sb, sb, name);
 }
 
@@ -564,7 +556,6 @@ int erofs_fscache_register_fs(struct super_block *sb)
 	int ret;
 	struct erofs_sb_info *sbi = EROFS_SB(sb);
 	struct erofs_fscache *fscache;
-	unsigned int flags = 0;
 
 	if (sbi->domain_id)
 		ret = erofs_fscache_register_domain(sb);
@@ -573,19 +564,8 @@ int erofs_fscache_register_fs(struct super_block *sb)
 	if (ret)
 		return ret;
 
-	/*
-	 * When shared domain is enabled, using NEED_NOEXIST to guarantee
-	 * the primary data blob (aka fsid) is unique in the shared domain.
-	 *
-	 * For non-shared-domain case, fscache_acquire_volume() invoked by
-	 * erofs_fscache_register_volume() has already guaranteed
-	 * the uniqueness of primary data blob.
-	 *
-	 * Acquired domain/volume will be relinquished in kill_sb() on error.
-	 */
-	if (sbi->domain_id)
-		flags |= EROFS_REG_COOKIE_NEED_NOEXIST;
-	fscache = erofs_fscache_register_cookie(sb, sbi->fsid, flags);
+	/* acquired domain/volume will be relinquished in kill_sb() on error */
+	fscache = erofs_fscache_acquire_cookie(sb, sb, sbi->fsid);
 	if (IS_ERR(fscache))
 		return PTR_ERR(fscache);
 
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 125e4aa8d295..fded736bc3d5 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -570,7 +570,7 @@ int erofs_fscache_register_fs(struct super_block *sb);
 void erofs_fscache_unregister_fs(struct super_block *sb);
 
 struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
-					char *name, unsigned int flags);
+						    char *name);
 void erofs_fscache_unregister_cookie(struct erofs_fscache *fscache);
 #else
 static inline int erofs_fscache_register_fs(struct super_block *sb)
@@ -581,7 +581,7 @@ static inline void erofs_fscache_unregister_fs(struct super_block *sb) {}
 
 static inline
 struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
-					char *name, unsigned int flags)
+						    char *name)
 {
 	return ERR_PTR(-EOPNOTSUPP);
 }
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 19b1ae79cec4..8706ca34f26a 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -244,7 +244,7 @@ static int erofs_init_device(struct erofs_buf *buf, struct super_block *sb,
 	}
 
 	if (erofs_is_fscache_mode(sb)) {
-		fscache = erofs_fscache_register_cookie(sb, dif->path, 0);
+		fscache = erofs_fscache_register_cookie(sb, dif->path);
 		if (IS_ERR(fscache))
 			return PTR_ERR(fscache);
 		dif->fscache = fscache;
-- 
2.19.1.6.gb485710b

Re: [PATCH 4/4] erofs: simplify the name collision checking in share domain mode

[Jia Zhu]

在 2023/2/8 15:17, Jingbo Xu 写道:
> When share domain is enabled, data blobs can be shared among filesystem
> instances in the same domain for data deduplication, while bootstrap
> blobs are always dedicated to the corresponding filesystem instance, and
> have no need to be shared.
> 
> In the initial implementation of share domain (commit 7d41963759fe
> ("erofs: Support sharing cookies in the same domain")), bootstrap blobs
> are also in the share domain, and thus can be referenced by the
> following filesystem instances.  In this case, mounting twice with the
> same fsid and domain_id will trigger warning in sysfs.  Commit
> 27f2a2dcc626 ("erofs: check the uniqueness of fsid in shared domain in
> advance") fixes this by introducing the name collision checking.
> 
> This patch attempts to fix the above issue in another simpler way.
> Since the bootstrap blobs have no need to be shared, move them out of
> the share domain, so that one bootstrap blob can not be referenced by
> other filesystem instances.  Attempt to mount twice with the same fsid
> and domain_id will fail with info of duplicate cookies, which is
> consistent with the behavior in non-share-domain mode.
> 
> Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>

Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>

> ---
>   fs/erofs/fscache.c  | 36 ++++++++----------------------------
>   fs/erofs/internal.h |  4 ++--
>   fs/erofs/super.c    |  2 +-
>   3 files changed, 11 insertions(+), 31 deletions(-)
> 
> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
> index 8353a5fe8c71..8da6e05e9d23 100644
> --- a/fs/erofs/fscache.c
> +++ b/fs/erofs/fscache.c
> @@ -505,25 +505,18 @@ struct erofs_fscache *erofs_fscache_domain_init_cookie(struct super_block *sb,
>   
>   static
>   struct erofs_fscache *erofs_domain_register_cookie(struct super_block *sb,
> -						   char *name,
> -						   unsigned int flags)
> +						   char *name)
>   {
>   	struct erofs_fscache *ctx;
>   	struct erofs_domain *domain = EROFS_SB(sb)->domain;
>   
>   	mutex_lock(&erofs_domain_cookies_lock);
>   	list_for_each_entry(ctx, &erofs_domain_cookies_list, node) {
> -		if (ctx->domain != domain || strcmp(ctx->name, name))
> -			continue;
> -		if (!(flags & EROFS_REG_COOKIE_NEED_NOEXIST)) {
> +		if (ctx->domain == domain && !strcmp(ctx->name, name)) {
>   			refcount_inc(&ctx->ref);
> -		} else {
> -			erofs_err(sb, "%s already exists in domain %s", name,
> -				  domain->domain_id);
> -			ctx = ERR_PTR(-EEXIST);
> +			mutex_unlock(&erofs_domain_cookies_lock);
> +			return ctx;
>   		}
> -		mutex_unlock(&erofs_domain_cookies_lock);
> -		return ctx;
>   	}
>   	ctx = erofs_fscache_domain_init_cookie(sb, name);
>   	mutex_unlock(&erofs_domain_cookies_lock);
> @@ -531,11 +524,10 @@ struct erofs_fscache *erofs_domain_register_cookie(struct super_block *sb,
>   }
>   
>   struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
> -						    char *name,
> -						    unsigned int flags)
> +						    char *name)
>   {
>   	if (EROFS_SB(sb)->domain_id)
> -		return erofs_domain_register_cookie(sb, name, flags);
> +		return erofs_domain_register_cookie(sb, name);
>   	return erofs_fscache_acquire_cookie(sb, sb, name);
>   }
>   
> @@ -564,7 +556,6 @@ int erofs_fscache_register_fs(struct super_block *sb)
>   	int ret;
>   	struct erofs_sb_info *sbi = EROFS_SB(sb);
>   	struct erofs_fscache *fscache;
> -	unsigned int flags = 0;
>   
>   	if (sbi->domain_id)
>   		ret = erofs_fscache_register_domain(sb);
> @@ -573,19 +564,8 @@ int erofs_fscache_register_fs(struct super_block *sb)
>   	if (ret)
>   		return ret;
>   
> -	/*
> -	 * When shared domain is enabled, using NEED_NOEXIST to guarantee
> -	 * the primary data blob (aka fsid) is unique in the shared domain.
> -	 *
> -	 * For non-shared-domain case, fscache_acquire_volume() invoked by
> -	 * erofs_fscache_register_volume() has already guaranteed
> -	 * the uniqueness of primary data blob.
> -	 *
> -	 * Acquired domain/volume will be relinquished in kill_sb() on error.
> -	 */
> -	if (sbi->domain_id)
> -		flags |= EROFS_REG_COOKIE_NEED_NOEXIST;
> -	fscache = erofs_fscache_register_cookie(sb, sbi->fsid, flags);
> +	/* acquired domain/volume will be relinquished in kill_sb() on error */
> +	fscache = erofs_fscache_acquire_cookie(sb, sb, sbi->fsid);
>   	if (IS_ERR(fscache))
>   		return PTR_ERR(fscache);
>   
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 125e4aa8d295..fded736bc3d5 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -570,7 +570,7 @@ int erofs_fscache_register_fs(struct super_block *sb);
>   void erofs_fscache_unregister_fs(struct super_block *sb);
>   
>   struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
> -					char *name, unsigned int flags);
> +						    char *name);
>   void erofs_fscache_unregister_cookie(struct erofs_fscache *fscache);
>   #else
>   static inline int erofs_fscache_register_fs(struct super_block *sb)
> @@ -581,7 +581,7 @@ static inline void erofs_fscache_unregister_fs(struct super_block *sb) {}
>   
>   static inline
>   struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
> -					char *name, unsigned int flags)
> +						    char *name)
>   {
>   	return ERR_PTR(-EOPNOTSUPP);
>   }
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index 19b1ae79cec4..8706ca34f26a 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -244,7 +244,7 @@ static int erofs_init_device(struct erofs_buf *buf, struct super_block *sb,
>   	}
>   
>   	if (erofs_is_fscache_mode(sb)) {
> -		fscache = erofs_fscache_register_cookie(sb, dif->path, 0);
> +		fscache = erofs_fscache_register_cookie(sb, dif->path);
>   		if (IS_ERR(fscache))
>   			return PTR_ERR(fscache);
>   		dif->fscache = fscache;

Re: [PATCH 4/4] erofs: simplify the name collision checking in share domain mode

[Jingbo Xu]

On 2/8/23 3:17 PM, Jingbo Xu wrote:
> When share domain is enabled, data blobs can be shared among filesystem
> instances in the same domain for data deduplication, while bootstrap
> blobs are always dedicated to the corresponding filesystem instance, and
> have no need to be shared.
> 
> In the initial implementation of share domain (commit 7d41963759fe
> ("erofs: Support sharing cookies in the same domain")), bootstrap blobs
> are also in the share domain, and thus can be referenced by the
> following filesystem instances.  In this case, mounting twice with the
> same fsid and domain_id will trigger warning in sysfs.  Commit
> 27f2a2dcc626 ("erofs: check the uniqueness of fsid in shared domain in
> advance") fixes this by introducing the name collision checking.
> 
> This patch attempts to fix the above issue in another simpler way.
> Since the bootstrap blobs have no need to be shared, move them out of
> the share domain, so that one bootstrap blob can not be referenced by
> other filesystem instances.  Attempt to mount twice with the same fsid
> and domain_id will fail with info of duplicate cookies, which is
> consistent with the behavior in non-share-domain mode.
> 

In non-share-domain mode, the uniqueness of primary data blob is
actually guaranteed by fscache_acquire_volume(), since
fscache_acquire_volume() will fail if attempt to mount the same fsid twice.

Thus hold on for this patch.


-- 
Thanks,
Jingbo

[PATCH] erofs: relinquish volume with mutex held

[Jingbo Xu]

Relinquish fscache volume with mutex held.  Otherwise if a new domain is
registered when the old domain with the same name gets removed from the
list but not relinquished yet, fscache may complain the collision.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
---
 fs/erofs/fscache.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index 8da6e05e9d23..35b2d8b5773e 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -328,8 +328,8 @@ static void erofs_fscache_domain_put(struct erofs_domain *domain)
 			kern_unmount(erofs_pseudo_mnt);
 			erofs_pseudo_mnt = NULL;
 		}
-		mutex_unlock(&erofs_domain_list_lock);
 		fscache_relinquish_volume(domain->volume, NULL, false);
+		mutex_unlock(&erofs_domain_list_lock);
 		kfree(domain->domain_id);
 		kfree(domain);
 		return;
-- 
2.19.1.6.gb485710b

Re: [External] [PATCH] erofs: relinquish volume with mutex held

[Jia Zhu]

在 2023/2/8 15:32, Jingbo Xu 写道:
> Relinquish fscache volume with mutex held.  Otherwise if a new domain is
> registered when the old domain with the same name gets removed from the
> list but not relinquished yet, fscache may complain the collision.
> 
> Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>

Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>

> ---
>   fs/erofs/fscache.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
> index 8da6e05e9d23..35b2d8b5773e 100644
> --- a/fs/erofs/fscache.c
> +++ b/fs/erofs/fscache.c
> @@ -328,8 +328,8 @@ static void erofs_fscache_domain_put(struct erofs_domain *domain)
>   			kern_unmount(erofs_pseudo_mnt);
>   			erofs_pseudo_mnt = NULL;
>   		}
> -		mutex_unlock(&erofs_domain_list_lock);
>   		fscache_relinquish_volume(domain->volume, NULL, false);
> +		mutex_unlock(&erofs_domain_list_lock);
>   		kfree(domain->domain_id);
>   		kfree(domain);
>   		return;