This was suggested by Miklos based on review from the previous
patch that introduced atomic open for positive dentries.
In open_last_lookups() the dentry was not used anymore when atomic
revalidate was available, which required to release the dentry,
then code fall through to lookup_open was done, which resulted
in another d_lookup and also d_revalidate. All of that can
be avoided by the new atomic_revalidate_open() function.
Another included change is the introduction of an enum as
d_revalidate return code.
Signed-off-by: Bernd Schubert <bschubert@xxxxxxx>
Cc: Miklos Szeredi <miklos@xxxxxxxxxx>
Cc: Dharmendra Singh <dsingh@xxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
---
fs/namei.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 43 insertions(+), 2 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index f01b278ac0ef..8ad7a0dfa596 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3388,6 +3388,44 @@ static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry,
return dentry;
}
+static struct dentry *atomic_revalidate_open(struct dentry *dentry,
+ struct nameidata *nd,
+ struct file *file,
+ const struct open_flags *op,
+ bool *got_write)
+{
+ struct mnt_idmap *idmap;
+ struct dentry *dir = nd->path.dentry;
+ struct inode *dir_inode = dir->d_inode;
+ int open_flag = op->open_flag;
+ umode_t mode = op->mode;
+
+ if (unlikely(IS_DEADDIR(dir_inode)))
+ return ERR_PTR(-ENOENT);
+
+ file->f_mode &= ~FMODE_CREATED;
+
+ if (unlikely(open_flag & O_CREAT)) {
+ WARN_ON(1);
+ return ERR_PTR(-EINVAL);
+ }
+
+ if (open_flag & (O_TRUNC | O_WRONLY | O_RDWR))
+ *got_write = !mnt_want_write(nd->path.mnt);
+ else
+ *got_write = false;
+
+ if (!got_write)
+ open_flag &= ~O_TRUNC;
+
+ inode_lock_shared(dir->d_inode);
+ dentry = atomic_open(nd, dentry, file, open_flag, mode);
+ inode_unlock_shared(dir->d_inode);
+
+ return dentry;
+
+}
+
/*
* Look up and maybe create and open the last component.
*
@@ -3541,8 +3579,10 @@ static const char *open_last_lookups(struct nameidata *nd,
if (IS_ERR(dentry))
return ERR_CAST(dentry);
if (dentry && unlikely(atomic_revalidate)) {
- dput(dentry);
- dentry = NULL;
+ BUG_ON(nd->flags & LOOKUP_RCU);
+ dentry = atomic_revalidate_open(dentry, nd, file, op,
+ &got_write);
+ goto drop_write;
}
if (likely(dentry))
goto finish_lookup;
@@ -3580,6 +3620,7 @@ static const char *open_last_lookups(struct nameidata *nd,
else
inode_unlock_shared(dir->d_inode);
+drop_write:
if (got_write)
mnt_drop_write(nd->path.mnt);
--
2.39.2
