linux-kernel - [PATCH v2 3/8] fs/9p: remove walk and inode allocation from symlink

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Message-Id: <20240108-ericvh-fix-cache-dups-v2-3-a73f8822838c@kernel.org>
Date: Mon, 08 Jan 2024 15:18:19 +0000
From: Eric Van Hensbergen <ericvh@...nel.org>
To: Latchesar Ionkov <lucho@...kov.net>, 
 Dominique Martinet <asmadeus@...ewreck.org>, 
 Christian Schoenebeck <linux_oss@...debyte.com>
Cc: v9fs@...ts.linux.dev, linux-kernel@...r.kernel.org, 
 Eric Van Hensbergen <ericvh@...nel.org>
Subject: [PATCH v2 3/8] fs/9p: remove walk and inode allocation from
 symlink

Symlink had a bunch of extra operations which essentially
end up discarded.  It was walking the fid to the new file and
creating an inode for it, but those semantics are part of
tsymlink.  This did prepopulate the cache, but that also seems
potentially unnecessary and frought with peril.

Signed-off-by: Eric Van Hensbergen <ericvh@...nel.org>
---
 fs/9p/vfs_inode_dotl.c | 33 ---------------------------------
 1 file changed, 33 deletions(-)

diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 981278d0788e..ab52a89367d2 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -690,14 +690,11 @@ v9fs_vfs_symlink_dotl(struct mnt_idmap *idmap, struct inode *dir,
 	kgid_t gid;
 	const unsigned char *name;
 	struct p9_qid qid;
-	struct inode *inode;
 	struct p9_fid *dfid;
 	struct p9_fid *fid = NULL;
-	struct v9fs_session_info *v9ses;
 
 	name = dentry->d_name.name;
 	p9_debug(P9_DEBUG_VFS, "%lu,%s,%s\n", dir->i_ino, name, symname);
-	v9ses = v9fs_inode2v9ses(dir);
 
 	dfid = v9fs_parent_fid(dentry);
 	if (IS_ERR(dfid)) {
@@ -717,36 +714,6 @@ v9fs_vfs_symlink_dotl(struct mnt_idmap *idmap, struct inode *dir,
 	}
 
 	v9fs_invalidate_inode_attr(dir);
-	if (v9ses->cache & (CACHE_META|CACHE_LOOSE)) {
-		/* Now walk from the parent so we can get an unopened fid. */
-		fid = p9_client_walk(dfid, 1, &name, 1);
-		if (IS_ERR(fid)) {
-			err = PTR_ERR(fid);
-			p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n",
-				 err);
-			goto error;
-		}
-
-		/* instantiate inode and assign the unopened fid to dentry */
-		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
-		if (IS_ERR(inode)) {
-			err = PTR_ERR(inode);
-			p9_debug(P9_DEBUG_VFS, "inode creation failed %d\n",
-				 err);
-			goto error;
-		}
-		v9fs_fid_add(dentry, &fid);
-		d_instantiate(dentry, inode);
-		err = 0;
-	} else {
-		/* Not in cached mode. No need to populate inode with stat */
-		inode = v9fs_get_inode(dir->i_sb, S_IFLNK, 0);
-		if (IS_ERR(inode)) {
-			err = PTR_ERR(inode);
-			goto error;
-		}
-		d_instantiate(dentry, inode);
-	}
 
 error:
 	p9_fid_put(fid);

-- 
2.41.0