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vfs: break parent dir delegations in open(..., O_CREAT) codepath

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In order to add directory delegation support, we need to break
delegations on the parent whenever there is going to be a change in the
directory.

Add a delegated_inode parameter to lookup_open and have it break the
delegation. Then, open_last_lookups can wait for the delegation break
and retry the call to lookup_open once it's done.

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-v6-8-52f3feebb2f2@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Jeff Layton 2025-11-11 09:12:49 -05:00 committed by Christian Brauner
parent 4fa76319cd
commit 134796f43a
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
1 changed files with 18 additions and 4 deletions
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22
fs/namei.c
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@ -3697,7 +3697,7 @@ static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry,
*/
static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
const struct open_flags *op,
bool got_write)
bool got_write, struct delegated_inode *delegated_inode)
{
struct mnt_idmap *idmap;
struct dentry *dir = nd->path.dentry;
@ -3786,6 +3786,11 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
/* Negative dentry, just create the file */
if (!dentry->d_inode && (open_flag & O_CREAT)) {
/* but break the directory lease first! */
error = try_break_deleg(dir_inode, delegated_inode);
if (error)
goto out_dput;
file->f_mode |= FMODE_CREATED;
audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
if (!dir_inode->i_op->create) {
@ -3848,6 +3853,7 @@ static struct dentry *lookup_fast_for_open(struct nameidata *nd, int open_flag)
static const char *open_last_lookups(struct nameidata *nd,
struct file *file, const struct open_flags *op)
{
struct delegated_inode delegated_inode = { };
struct dentry *dir = nd->path.dentry;
int open_flag = op->open_flag;
bool got_write = false;
@ -3879,7 +3885,7 @@ static const char *open_last_lookups(struct nameidata *nd,
return ERR_PTR(-ECHILD);
}
}
retry:
if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {
got_write = !mnt_want_write(nd->path.mnt);
/*
@ -3892,7 +3898,7 @@ static const char *open_last_lookups(struct nameidata *nd,
inode_lock(dir->d_inode);
else
inode_lock_shared(dir->d_inode);
dentry = lookup_open(nd, file, op, got_write);
dentry = lookup_open(nd, file, op, got_write, &delegated_inode);
if (!IS_ERR(dentry)) {
if (file->f_mode & FMODE_CREATED)
fsnotify_create(dir->d_inode, dentry);
@ -3907,8 +3913,16 @@ static const char *open_last_lookups(struct nameidata *nd,
if (got_write)
mnt_drop_write(nd->path.mnt);
if (IS_ERR(dentry))
if (IS_ERR(dentry)) {
if (is_delegated(&delegated_inode)) {
int error = break_deleg_wait(&delegated_inode);
if (!error)
goto retry;
return ERR_PTR(error);
}
return ERR_CAST(dentry);
}
if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) {
dput(nd->path.dentry);