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ecryptfs: get rid of pointless mount references in ecryptfs dentries

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->lower_path.mnt has the same value for all dentries on given ecryptfs
instance and if somebody goes for mountpoint-crossing variant where that
would not be true, we can deal with that when it happens (and _not_
with duplicating these reference into each dentry).

As it is, we are better off just sticking a reference into ecryptfs-private
part of superblock and keeping it pinned until ->kill_sb().

That way we can stick a reference to underlying dentry right into ->d_fsdata
of ecryptfs one, getting rid of indirection through struct ecryptfs_dentry_info,
along with the entire struct ecryptfs_dentry_info machinery.

[kudos to Dan Carpenter for spotting a bug in ecryptfs_get_tree() part]

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
2025-07-24 22:45:09 -04:00
parent 75db7fd990
commit fc812c40f5
5 changed files with 30 additions and 69 deletions
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27
fs/ecryptfs/ecryptfs_kernel.h
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@@ -258,13 +258,6 @@ struct ecryptfs_inode_info {
struct ecryptfs_crypt_stat crypt_stat;
};
/* dentry private data. Each dentry must keep track of a lower
* vfsmount too. */
struct ecryptfs_dentry_info {
struct path lower_path;
struct rcu_head rcu;
};
/**
* ecryptfs_global_auth_tok - A key used to encrypt all new files under the mountpoint
* @flags: Status flags
@@ -348,6 +341,7 @@ struct ecryptfs_mount_crypt_stat {
/* superblock private data. */
struct ecryptfs_sb_info {
struct super_block *wsi_sb;
struct vfsmount *lower_mnt;
struct ecryptfs_mount_crypt_stat mount_crypt_stat;
};
@@ -494,22 +488,25 @@ ecryptfs_set_superblock_lower(struct super_block *sb,
}
static inline void
ecryptfs_set_dentry_private(struct dentry *dentry,
struct ecryptfs_dentry_info *dentry_info)
ecryptfs_set_dentry_lower(struct dentry *dentry,
struct dentry *lower_dentry)
{
dentry->d_fsdata = dentry_info;
dentry->d_fsdata = lower_dentry;
}
static inline struct dentry *
ecryptfs_dentry_to_lower(struct dentry *dentry)
{
return ((struct ecryptfs_dentry_info *)dentry->d_fsdata)->lower_path.dentry;
return dentry->d_fsdata;
}
static inline const struct path *
ecryptfs_dentry_to_lower_path(struct dentry *dentry)
static inline struct path
ecryptfs_lower_path(struct dentry *dentry)
{
return &((struct ecryptfs_dentry_info *)dentry->d_fsdata)->lower_path;
return (struct path){
.mnt = ecryptfs_superblock_to_private(dentry->d_sb)->lower_mnt,
.dentry = ecryptfs_dentry_to_lower(dentry)
};
}
#define ecryptfs_printk(type, fmt, arg...) \
@@ -532,7 +529,6 @@ extern unsigned int ecryptfs_number_of_users;
extern struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
extern struct kmem_cache *ecryptfs_file_info_cache;
extern struct kmem_cache *ecryptfs_dentry_info_cache;
extern struct kmem_cache *ecryptfs_inode_info_cache;
extern struct kmem_cache *ecryptfs_sb_info_cache;
extern struct kmem_cache *ecryptfs_header_cache;
@@ -557,7 +553,6 @@ int ecryptfs_encrypt_and_encode_filename(
size_t *encoded_name_size,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
const char *name, size_t name_size);
struct dentry *ecryptfs_lower_dentry(struct dentry *this_dentry);
void ecryptfs_dump_hex(char *data, int bytes);
int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
int sg_size);