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erofs: introduce a pseudo mnt to manage shared cookies
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Use a pseudo mnt to manage shared cookies.

Signed-off-by: Jia Zhu <[email protected]>
Reviewed-by: Jingbo Xu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Gao Xiang <[email protected]>
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Jia Zhu authored and hsiangkao committed Sep 20, 2022
1 parent 8b7adf1 commit a984956
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Showing 3 changed files with 45 additions and 2 deletions.
13 changes: 13 additions & 0 deletions fs/erofs/fscache.c
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@

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)
Expand Down Expand Up @@ -432,6 +433,10 @@ static void erofs_fscache_domain_put(struct erofs_domain *domain)
mutex_lock(&erofs_domain_list_lock);
if (refcount_dec_and_test(&domain->ref)) {
list_del(&domain->list);
if (list_empty(&erofs_domain_list)) {
kern_unmount(erofs_pseudo_mnt);
erofs_pseudo_mnt = NULL;
}
mutex_unlock(&erofs_domain_list_lock);
fscache_relinquish_volume(domain->volume, NULL, false);
kfree(domain->domain_id);
Expand Down Expand Up @@ -486,6 +491,14 @@ static int erofs_fscache_init_domain(struct super_block *sb)
if (err)
goto out;

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;
}
}

domain->volume = sbi->volume;
refcount_set(&domain->ref, 1);
list_add(&domain->list, &erofs_domain_list);
Expand Down
1 change: 1 addition & 0 deletions fs/erofs/internal.h
Original file line number Diff line number Diff line change
Expand Up @@ -373,6 +373,7 @@ 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;
Expand Down
33 changes: 31 additions & 2 deletions fs/erofs/super.c
Original file line number Diff line number Diff line change
Expand Up @@ -676,6 +676,13 @@ 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;
Expand Down Expand Up @@ -776,6 +783,11 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
return 0;
}

static int erofs_fc_anon_get_tree(struct fs_context *fc)
{
return get_tree_nodev(fc, erofs_fc_fill_pseudo_super);
}

static int erofs_fc_get_tree(struct fs_context *fc)
{
struct erofs_fs_context *ctx = fc->fs_private;
Expand Down Expand Up @@ -844,10 +856,21 @@ static const struct fs_context_operations erofs_context_ops = {
.free = erofs_fc_free,
};

static const struct fs_context_operations erofs_anon_context_ops = {
.get_tree = erofs_fc_anon_get_tree,
};

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;

/* pseudo mount for anon inodes */
if (fc->sb_flags & SB_KERNMOUNT) {
fc->ops = &erofs_anon_context_ops;
return 0;
}

ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
if (!ctx)
return -ENOMEM;
ctx->devs = kzalloc(sizeof(struct erofs_dev_context), GFP_KERNEL);
Expand All @@ -874,6 +897,12 @@ static void erofs_kill_sb(struct super_block *sb)

WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);

/* pseudo mount for anon inodes */
if (sb->s_flags & SB_KERNMOUNT) {
kill_anon_super(sb);
return;
}

if (erofs_is_fscache_mode(sb))
kill_anon_super(sb);
else
Expand Down Expand Up @@ -907,7 +936,7 @@ static void erofs_put_super(struct super_block *sb)
erofs_fscache_unregister_fs(sb);
}

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,
Expand Down

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