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smb/server: use end_removing_noperm for for target of smb2_create_link()

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Sometimes smb2_create_link() needs to remove the target before creating
the link.
It uses ksmbd_vfs_kern_locked(), and is the only user of that interface.

To match the new naming, that function is changed to
ksmbd_vfs_kern_start_removing(), and related functions or flags are also
renamed.

The lock actually happens in ksmbd_vfs_path_lookup() and that is changed
to use start_removing_noperm() - permission to perform lookup in the
parent was already checked in vfs_path_parent_lookup().

Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20251113002050.676694-8-neilb@ownmail.net
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
NeilBrown
2025-11-13 11:18:30 +11:00
committed by Christian Brauner
parent c9ba789dad
commit 1ead2213dd
3 changed files with 19 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
fs/smb/server/smb2pdu.c
View File

@@ -6084,8 +6084,8 @@ static int smb2_create_link(struct ksmbd_work *work,
} }
ksmbd_debug(SMB, "target name is %s\n", target_name); ksmbd_debug(SMB, "target name is %s\n", target_name);
rc = ksmbd_vfs_kern_path_locked(work, link_name, LOOKUP_NO_SYMLINKS, rc = ksmbd_vfs_kern_path_start_removing(work, link_name, LOOKUP_NO_SYMLINKS,
&path, 0); &path, 0);
if (rc) { if (rc) {
if (rc != -ENOENT) if (rc != -ENOENT)
goto out; goto out;
@@ -6103,7 +6103,7 @@ static int smb2_create_link(struct ksmbd_work *work,
ksmbd_debug(SMB, "link already exists\n"); ksmbd_debug(SMB, "link already exists\n");
goto out; goto out;
} }
ksmbd_vfs_kern_path_unlock(&path); ksmbd_vfs_kern_path_end_removing(&path);
} }
rc = ksmbd_vfs_link(work, target_name, link_name); rc = ksmbd_vfs_link(work, target_name, link_name);
if (rc) if (rc)

27
fs/smb/server/vfs.c
View File

@@ -69,7 +69,7 @@ int ksmbd_vfs_lock_parent(struct dentry *parent, struct dentry *child)
static int ksmbd_vfs_path_lookup(struct ksmbd_share_config *share_conf, static int ksmbd_vfs_path_lookup(struct ksmbd_share_config *share_conf,
char *pathname, unsigned int flags, char *pathname, unsigned int flags,
struct path *path, bool do_lock) struct path *path, bool for_remove)
{ {
struct qstr last; struct qstr last;
struct filename *filename __free(putname) = NULL; struct filename *filename __free(putname) = NULL;
@@ -99,22 +99,20 @@ static int ksmbd_vfs_path_lookup(struct ksmbd_share_config *share_conf,
return -ENOENT; return -ENOENT;
} }
if (do_lock) { if (for_remove) {
err = mnt_want_write(path->mnt); err = mnt_want_write(path->mnt);
if (err) { if (err) {
path_put(path); path_put(path);
return -ENOENT; return -ENOENT;
} }
inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); d = start_removing_noperm(path->dentry, &last);
d = lookup_one_qstr_excl(&last, path->dentry, 0);
if (!IS_ERR(d)) { if (!IS_ERR(d)) {
dput(path->dentry); dput(path->dentry);
path->dentry = d; path->dentry = d;
return 0; return 0;
} }
inode_unlock(path->dentry->d_inode);
mnt_drop_write(path->mnt); mnt_drop_write(path->mnt);
path_put(path); path_put(path);
return -ENOENT; return -ENOENT;
@@ -1207,7 +1205,7 @@ static int ksmbd_vfs_lookup_in_dir(const struct path *dir, char *name,
static static
int __ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath, int __ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath,
unsigned int flags, unsigned int flags,
struct path *path, bool caseless, bool do_lock) struct path *path, bool caseless, bool for_remove)
{ {
struct ksmbd_share_config *share_conf = work->tcon->share_conf; struct ksmbd_share_config *share_conf = work->tcon->share_conf;
struct path parent_path; struct path parent_path;
@@ -1215,7 +1213,7 @@ int __ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath,
int err; int err;
retry: retry:
err = ksmbd_vfs_path_lookup(share_conf, filepath, flags, path, do_lock); err = ksmbd_vfs_path_lookup(share_conf, filepath, flags, path, for_remove);
if (!err || !caseless) if (!err || !caseless)
return err; return err;
@@ -1286,7 +1284,7 @@ int ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath,
} }
/** /**
* ksmbd_vfs_kern_path_locked() - lookup a file and get path info * ksmbd_vfs_kern_path_start_remove() - lookup a file and get path info prior to removal
* @work: work * @work: work
* @filepath: file path that is relative to share * @filepath: file path that is relative to share
* @flags: lookup flags * @flags: lookup flags
@@ -1298,20 +1296,19 @@ int ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath,
* filesystem will have been gained. * filesystem will have been gained.
* Return: 0 on if file was found, otherwise error * Return: 0 on if file was found, otherwise error
*/ */
int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *filepath, int ksmbd_vfs_kern_path_start_removing(struct ksmbd_work *work, char *filepath,
unsigned int flags, unsigned int flags,
struct path *path, bool caseless) struct path *path, bool caseless)
{ {
return __ksmbd_vfs_kern_path(work, filepath, flags, path, return __ksmbd_vfs_kern_path(work, filepath, flags, path,
caseless, true); caseless, true);
} }
void ksmbd_vfs_kern_path_unlock(const struct path *path) void ksmbd_vfs_kern_path_end_removing(const struct path *path)
{ {
/* While lock is still held, ->d_parent is safe */ end_removing(path->dentry);
inode_unlock(d_inode(path->dentry->d_parent));
mnt_drop_write(path->mnt); mnt_drop_write(path->mnt);
path_put(path); mntput(path->mnt);
} }
struct dentry *ksmbd_vfs_kern_path_create(struct ksmbd_work *work, struct dentry *ksmbd_vfs_kern_path_create(struct ksmbd_work *work,

8
fs/smb/server/vfs.h
View File

@@ -120,10 +120,10 @@ int ksmbd_vfs_remove_xattr(struct mnt_idmap *idmap,
int ksmbd_vfs_kern_path(struct ksmbd_work *work, char *name, int ksmbd_vfs_kern_path(struct ksmbd_work *work, char *name,
unsigned int flags, unsigned int flags,
struct path *path, bool caseless); struct path *path, bool caseless);
int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *name, int ksmbd_vfs_kern_path_start_removing(struct ksmbd_work *work, char *name,
unsigned int flags, unsigned int flags,
struct path *path, bool caseless); struct path *path, bool caseless);
void ksmbd_vfs_kern_path_unlock(const struct path *path); void ksmbd_vfs_kern_path_end_removing(const struct path *path);
struct dentry *ksmbd_vfs_kern_path_create(struct ksmbd_work *work, struct dentry *ksmbd_vfs_kern_path_create(struct ksmbd_work *work,
const char *name, const char *name,
unsigned int flags, unsigned int flags,