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ovl: narrow locking in ovl_workdir_create()

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In ovl_workdir_create() don't hold the dir lock for the whole time, but
only take it when needed.

It now gets taken separately for ovl_workdir_cleanup().  A subsequent
patch will move the locking into that function.

Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/20250716004725.1206467-13-neil@brown.name
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
NeilBrown 2025-07-16 10:44:23 +10:00 committed by Christian Brauner
parent 8290fb412d
commit 61eb7fec9e
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
1 changed files with 14 additions and 11 deletions
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25
fs/overlayfs/super.c
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@ -299,8 +299,8 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
int err;
bool retried = false;
inode_lock_nested(dir, I_MUTEX_PARENT);
retry:
inode_lock_nested(dir, I_MUTEX_PARENT);
work = ovl_lookup_upper(ofs, name, ofs->workbasedir, strlen(name));
if (!IS_ERR(work)) {
@ -311,23 +311,28 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
if (work->d_inode) {
err = -EEXIST;
inode_unlock(dir);
if (retried)
goto out_dput;
if (persist)
goto out_unlock;
return work;
retried = true;
err = ovl_workdir_cleanup(ofs, dir, mnt, work, 0);
dput(work);
if (err == -EINVAL) {
work = ERR_PTR(err);
goto out_unlock;
err = ovl_parent_lock(ofs->workbasedir, work);
if (!err) {
err = ovl_workdir_cleanup(ofs, dir, mnt, work, 0);
ovl_parent_unlock(ofs->workbasedir);
}
dput(work);
if (err == -EINVAL)
return ERR_PTR(err);
goto retry;
}
work = ovl_do_mkdir(ofs, dir, work, attr.ia_mode);
inode_unlock(dir);
err = PTR_ERR(work);
if (IS_ERR(work))
goto out_err;
@ -365,11 +370,10 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
if (err)
goto out_dput;
} else {
inode_unlock(dir);
err = PTR_ERR(work);
goto out_err;
}
out_unlock:
inode_unlock(dir);
return work;
out_dput:
@ -377,8 +381,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
out_err:
pr_warn("failed to create directory %s/%s (errno: %i); mounting read-only\n",
ofs->config.workdir, name, -err);
work = NULL;
goto out_unlock;
return NULL;
}
static int ovl_check_namelen(const struct path *path, struct ovl_fs *ofs,