Messages in this thread | | | Date | Tue, 13 Sep 2022 20:59:47 +0800 | Subject | Re: [External] Re: [PATCH V2 5/5] erofs: support fscache based shared domain | From | Jia Zhu <> |
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在 2022/9/13 14:27, JeffleXu 写道: > > > On 9/2/22 6:53 PM, Jia Zhu wrote: >> Several erofs filesystems can belong to one domain, and data blobs can >> be shared among these erofs filesystems of same domain. >> >> Users could specify domain_id mount option to create or join into a domain. >> >> Signed-off-by: Jia Zhu <zhujia.zj@bytedance.com> >> --- >> fs/erofs/fscache.c | 73 +++++++++++++++++++++++++++++++++++++++++++++ >> fs/erofs/internal.h | 12 ++++++++ >> fs/erofs/super.c | 10 +++++-- >> 3 files changed, 93 insertions(+), 2 deletions(-) >> >> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c >> index 439dd3cc096a..c01845808ede 100644 >> --- a/fs/erofs/fscache.c >> +++ b/fs/erofs/fscache.c >> @@ -559,12 +559,27 @@ int erofs_fscache_register_cookie(struct super_block *sb, >> void erofs_fscache_unregister_cookie(struct erofs_fscache **fscache) >> { >> struct erofs_fscache *ctx = *fscache; >> + struct erofs_domain *domain; >> >> if (!ctx) >> return; >> + domain = ctx->domain; >> + if (domain) { >> + mutex_lock(&domain->mutex); >> + /* Cookie is still in use */ >> + if (atomic_read(&ctx->anon_inode->i_count) > 1) { >> + iput(ctx->anon_inode); >> + mutex_unlock(&domain->mutex); >> + return; >> + } >> + iput(ctx->anon_inode); >> + kfree(ctx->name); >> + mutex_unlock(&domain->mutex); >> + } >> >> fscache_unuse_cookie(ctx->cookie, NULL, NULL); >> fscache_relinquish_cookie(ctx->cookie, false); >> + erofs_fscache_domain_put(domain); >> ctx->cookie = NULL; >> >> iput(ctx->inode); >> @@ -609,3 +624,61 @@ void erofs_fscache_unregister_fs(struct super_block *sb) >> sbi->volume = NULL; >> sbi->domain = NULL; >> } >> + >> +static int erofs_fscache_domain_init_cookie(struct super_block *sb, >> + struct erofs_fscache **fscache, char *name, bool need_inode) >> +{ >> + int ret; >> + struct inode *inode; >> + struct erofs_fscache *ctx; >> + struct erofs_sb_info *sbi = EROFS_SB(sb); >> + struct erofs_domain *domain = sbi->domain; >> + >> + ret = erofs_fscache_register_cookie(sb, &ctx, name, need_inode); >> + if (ret) >> + return ret; >> + >> + ctx->name = kstrdup(name, GFP_KERNEL); >> + if (!ctx->name) >> + return -ENOMEM; > > Shall we clean up the above registered cookie in the error path? > If this step fails, error will be transmitted to vfs_get_tree() and erofs_kill_sb() will relinquish the cookie. >> + >> + inode = new_inode(erofs_pseudo_mnt->mnt_sb); >> + if (!inode) { >> + kfree(ctx->name); >> + return -ENOMEM; >> + } > > Ditto. > >> + >> + ctx->domain = domain; >> + ctx->anon_inode = inode; >> + inode->i_private = ctx; >> + erofs_fscache_domain_get(domain); >> + *fscache = ctx; >> + return 0; >> +} >> + >> +int erofs_domain_register_cookie(struct super_block *sb, >> + struct erofs_fscache **fscache, char *name, bool need_inode) >> +{ >> + int err; >> + struct inode *inode; >> + struct erofs_fscache *ctx; >> + struct erofs_sb_info *sbi = EROFS_SB(sb); >> + struct erofs_domain *domain = sbi->domain; >> + struct super_block *psb = erofs_pseudo_mnt->mnt_sb; >> + >> + mutex_lock(&domain->mutex); > > What is domain->mutex used for? > This lock is used to avoid race conditions between cookie's traverse/del/insert in the inode list. It seems to be possible to increase the granularity of the lock after v2's change "Only initialize one pseudo fs to manage anonymous inodes(cookies).". > >> + list_for_each_entry(inode, &psb->s_inodes, i_sb_list) { >> + ctx = inode->i_private; >> + if (!ctx) >> + continue; >> + if (!strcmp(ctx->name, name)) { >> + *fscache = ctx; >> + igrab(inode); >> + mutex_unlock(&domain->mutex); >> + return 0; >> + } >> + } >> + err = erofs_fscache_domain_init_cookie(sb, fscache, name, need_inode); >> + mutex_unlock(&domain->mutex); >> + return err; >> +} >> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h >> index 2790c93ffb83..efa4f4ad77cc 100644 >> --- a/fs/erofs/internal.h >> +++ b/fs/erofs/internal.h >> @@ -110,6 +110,9 @@ struct erofs_domain { >> struct erofs_fscache { >> struct fscache_cookie *cookie; >> struct inode *inode; >> + struct inode *anon_inode; > > Why can't we reuse @inode for anon_inode? > We use pseudo sb's anonymous inodes list to manage the cookie. Wouldn't it be a bit of messy if reuses erofs meta inode? > >> + struct erofs_domain *domain; >> + char *name; >> }; >> >> struct erofs_sb_info { >> @@ -625,6 +628,9 @@ int erofs_fscache_register_domain(struct super_block *sb); >> int erofs_fscache_register_cookie(struct super_block *sb, >> struct erofs_fscache **fscache, >> char *name, bool need_inode); >> +int erofs_domain_register_cookie(struct super_block *sb, >> + struct erofs_fscache **fscache, >> + char *name, bool need_inode); >> void erofs_fscache_unregister_cookie(struct erofs_fscache **fscache); >> >> extern const struct address_space_operations erofs_fscache_access_aops; >> @@ -646,6 +652,12 @@ static inline int erofs_fscache_register_cookie(struct super_block *sb, >> { >> return -EOPNOTSUPP; >> } >> +static inline int erofs_domain_register_cookie(struct super_block *sb, >> + struct erofs_fscache **fscache, >> + char *name, bool need_inode) >> +{ >> + return -EOPNOTSUPP; >> +} >> >> static inline void erofs_fscache_unregister_cookie(struct erofs_fscache **fscache) >> { >> diff --git a/fs/erofs/super.c b/fs/erofs/super.c >> index 667a78f0ee70..11c5ba84567c 100644 >> --- a/fs/erofs/super.c >> +++ b/fs/erofs/super.c >> @@ -245,8 +245,12 @@ static int erofs_init_device(struct erofs_buf *buf, struct super_block *sb, >> } >> >> if (erofs_is_fscache_mode(sb)) { >> - ret = erofs_fscache_register_cookie(sb, &dif->fscache, >> - dif->path, false); >> + if (sbi->opt.domain_id) >> + ret = erofs_domain_register_cookie(sb, &dif->fscache, dif->path, >> + false); >> + else >> + ret = erofs_fscache_register_cookie(sb, &dif->fscache, dif->path, >> + false); >> if (ret) >> return ret; >> } else { >> @@ -726,6 +730,8 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc) >> err = erofs_fscache_register_domain(sb); >> if (err) >> return err; >> + err = erofs_domain_register_cookie(sb, &sbi->s_fscache, >> + sbi->opt.fsid, true); >> } else { >> err = erofs_fscache_register_fs(sb); >> if (err) >
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