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

From: Jia Zhu
Date: Wed Feb 08 2023 - 03:16:41 EST




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@xxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxxxx>
---
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;
};