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vfs: make vfs_symlink break delegations on parent dir 

In order to add directory delegation support, we must break delegations
on the parent on any change to the directory.

Add a delegated_inode parameter to vfs_symlink() and have it break the
delegation. do_symlinkat() can then wait on the delegation break before
proceeding.

Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-12-52f3feebb2f2@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Jeff Layton 2025-11-11 09:12:53 -05:00 committed by Christian Brauner
parent e8960c1b2e
commit 92bf53577f
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
6 changed files with 19 additions and 7 deletions
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2
fs/ecryptfs/inode.c
View File

@ -479,7 +479,7 @@ static int ecryptfs_symlink(struct mnt_idmap *idmap,
if (rc)
goto out_lock;
rc = vfs_symlink(&nop_mnt_idmap, lower_dir, lower_dentry,
encoded_symname);
encoded_symname, NULL);
kfree(encoded_symname);
if (rc || d_really_is_negative(lower_dentry))
goto out_lock;

2
fs/init.c
View File

@ -209,7 +209,7 @@ int __init init_symlink(const char *oldname, const char *newname)
error = security_path_symlink(&path, dentry, oldname);
if (!error)
error = vfs_symlink(mnt_idmap(path.mnt), path.dentry->d_inode,
dentry, oldname);
dentry, oldname, NULL);
end_creating_path(&path, dentry);
return error;
}

16
fs/namei.c
View File

@ -4845,6 +4845,7 @@ SYSCALL_DEFINE1(unlink, const char __user *, pathname)
* @dir: inode of the parent directory
* @dentry: dentry of the child symlink file
* @oldname: name of the file to link to
* @delegated_inode: returns victim inode, if the inode is delegated.
*
* Create a symlink.
*
@ -4855,7 +4856,8 @@ SYSCALL_DEFINE1(unlink, const char __user *, pathname)
* raw inode simply pass @nop_mnt_idmap.
*/
int vfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, const char *oldname)
struct dentry *dentry, const char *oldname,
struct delegated_inode *delegated_inode)
{
int error;
@ -4870,6 +4872,10 @@ int vfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
if (error)
return error;
error = try_break_deleg(dir, delegated_inode);
if (error)
return error;
error = dir->i_op->symlink(idmap, dir, dentry, oldname);
if (!error)
fsnotify_create(dir, dentry);
@ -4883,6 +4889,7 @@ int do_symlinkat(struct filename *from, int newdfd, struct filename *to)
struct dentry *dentry;
struct path path;
unsigned int lookup_flags = 0;
struct delegated_inode delegated_inode = { };
if (IS_ERR(from)) {
error = PTR_ERR(from);
@ -4897,8 +4904,13 @@ int do_symlinkat(struct filename *from, int newdfd, struct filename *to)
error = security_path_symlink(&path, dentry, from->name);
if (!error)
error = vfs_symlink(mnt_idmap(path.mnt), path.dentry->d_inode,
dentry, from->name);
dentry, from->name, &delegated_inode);
end_creating_path(&path, dentry);
if (is_delegated(&delegated_inode)) {
error = break_deleg_wait(&delegated_inode);
if (!error)
goto retry;
}
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
goto retry;

2
fs/nfsd/vfs.c
View File

@ -1742,7 +1742,7 @@ nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
err = fh_fill_pre_attrs(fhp);
if (err != nfs_ok)
goto out_unlock;
host_err = vfs_symlink(&nop_mnt_idmap, d_inode(dentry), dnew, path);
host_err = vfs_symlink(&nop_mnt_idmap, d_inode(dentry), dnew, path, NULL);
err = nfserrno(host_err);
cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
if (!err)

2
fs/overlayfs/overlayfs.h
View File

@ -267,7 +267,7 @@ static inline int ovl_do_symlink(struct ovl_fs *ofs,
struct inode *dir, struct dentry *dentry,
const char *oldname)
{
int err = vfs_symlink(ovl_upper_mnt_idmap(ofs), dir, dentry, oldname);
int err = vfs_symlink(ovl_upper_mnt_idmap(ofs), dir, dentry, oldname, NULL);
pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
return err;

2
include/linux/fs.h
View File

@ -2118,7 +2118,7 @@ struct dentry *vfs_mkdir(struct mnt_idmap *, struct inode *,
int vfs_mknod(struct mnt_idmap *, struct inode *, struct dentry *,
umode_t, dev_t, struct delegated_inode *);
int vfs_symlink(struct mnt_idmap *, struct inode *,
struct dentry *, const char *);
struct dentry *, const char *, struct delegated_inode *);
int vfs_link(struct dentry *, struct mnt_idmap *, struct inode *,
struct dentry *, struct delegated_inode *);
int vfs_rmdir(struct mnt_idmap *, struct inode *, struct dentry *,