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From: Jeff Layton <jlayton@kernel.org>
Date: Mon, 18 Mar 2024 14:28:50 -0400
Subject: [PATCH RFC] ntfs3: remove atomic_open
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Message-Id: <20240318-ntfs3-atomic-open-v1-1-57afed48fe86@kernel.org>
To: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>, 
 Christian Brauner <brauner@kernel.org>, ntfs3@lists.linux.dev, 
 linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, 
 Jeff Layton <jlayton@kernel.org>

atomic_open is an optional VFS operation, and is primarily for network
filesystems. NFS (for instance) can just send an open call for the last
path component rather than doing a lookup and then having to follow that
up with an open when it doesn't have a dentry in cache.

ntfs3 is a local filesystem however, and its atomic_open just does a
typical lookup + open, but in a convoluted way. atomic_open will also
make directory leases more difficult to implement on the filesystem.

Remove ntfs_atomic_open.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
Am I missing something about why ntfs3 requires an atomic_open op? In
any case, this is only lightly tested, but it seems to work.
---
 fs/ntfs3/namei.c | 90 --------------------------------------------------------
 1 file changed, 90 deletions(-)

diff --git a/fs/ntfs3/namei.c b/fs/ntfs3/namei.c
index 084d19d78397..edb6a7141246 100644
--- a/fs/ntfs3/namei.c
+++ b/fs/ntfs3/namei.c
@@ -358,95 +358,6 @@ static int ntfs_rename(struct mnt_idmap *idmap, struct inode *dir,
 	return err;
 }
 
-/*
- * ntfs_atomic_open
- *
- * inode_operations::atomic_open
- */
-static int ntfs_atomic_open(struct inode *dir, struct dentry *dentry,
-			    struct file *file, u32 flags, umode_t mode)
-{
-	int err;
-	struct inode *inode;
-	struct ntfs_fnd *fnd = NULL;
-	struct ntfs_inode *ni = ntfs_i(dir);
-	struct dentry *d = NULL;
-	struct cpu_str *uni = __getname();
-	bool locked = false;
-
-	if (!uni)
-		return -ENOMEM;
-
-	err = ntfs_nls_to_utf16(ni->mi.sbi, dentry->d_name.name,
-				dentry->d_name.len, uni, NTFS_NAME_LEN,
-				UTF16_HOST_ENDIAN);
-	if (err < 0)
-		goto out;
-
-#ifdef CONFIG_NTFS3_FS_POSIX_ACL
-	if (IS_POSIXACL(dir)) {
-		/*
-		 * Load in cache current acl to avoid ni_lock(dir):
-		 * ntfs_create_inode -> ntfs_init_acl -> posix_acl_create ->
-		 * ntfs_get_acl -> ntfs_get_acl_ex -> ni_lock
-		 */
-		struct posix_acl *p = get_inode_acl(dir, ACL_TYPE_DEFAULT);
-
-		if (IS_ERR(p)) {
-			err = PTR_ERR(p);
-			goto out;
-		}
-		posix_acl_release(p);
-	}
-#endif
-
-	if (d_in_lookup(dentry)) {
-		ni_lock_dir(ni);
-		locked = true;
-		fnd = fnd_get();
-		if (!fnd) {
-			err = -ENOMEM;
-			goto out1;
-		}
-
-		d = d_splice_alias(dir_search_u(dir, uni, fnd), dentry);
-		if (IS_ERR(d)) {
-			err = PTR_ERR(d);
-			d = NULL;
-			goto out2;
-		}
-
-		if (d)
-			dentry = d;
-	}
-
-	if (!(flags & O_CREAT) || d_really_is_positive(dentry)) {
-		err = finish_no_open(file, d);
-		goto out2;
-	}
-
-	file->f_mode |= FMODE_CREATED;
-
-	/*
-	 * fnd contains tree's path to insert to.
-	 * If fnd is not NULL then dir is locked.
-	 */
-	inode = ntfs_create_inode(file_mnt_idmap(file), dir, dentry, uni,
-				  mode, 0, NULL, 0, fnd);
-	err = IS_ERR(inode) ? PTR_ERR(inode) :
-			      finish_open(file, dentry, ntfs_file_open);
-	dput(d);
-
-out2:
-	fnd_put(fnd);
-out1:
-	if (locked)
-		ni_unlock(ni);
-out:
-	__putname(uni);
-	return err;
-}
-
 struct dentry *ntfs3_get_parent(struct dentry *child)
 {
 	struct inode *inode = d_inode(child);
@@ -612,7 +523,6 @@ const struct inode_operations ntfs_dir_inode_operations = {
 	.setattr	= ntfs3_setattr,
 	.getattr	= ntfs_getattr,
 	.listxattr	= ntfs_listxattr,
-	.atomic_open	= ntfs_atomic_open,
 	.fiemap		= ntfs_fiemap,
 };
 

---
base-commit: 0a7b0acecea273c8816f4f5b0e189989470404cf
change-id: 20240318-ntfs3-atomic-open-0cc979d7c024

Best regards,
-- 
Jeff Layton <jlayton@kernel.org>