Revert " fs/9p: mitigate inode collisions"

This reverts commit d05dcfdf5e1659b2949d13060284eff3888b644e.

This is a requirement to revert commit 724a08450f74 ("fs/9p: simplify
iget to remove unnecessary paths"), see that revert for details.

Fixes: 724a08450f74 ("fs/9p: simplify iget to remove unnecessary paths")
Reported-by: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/20240923100508.GA32066@willie-the-truck
Cc: stable@vger.kernel.org # v6.9+
Message-ID: <20241024-revert_iget-v1-1-4cac63d25f72@codewreck.org>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>

4 files changed, 22 insertions, 56 deletions

diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index 1775fcc7f0e8..9defa12208f9 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -179,14 +179,13 @@ extern int v9fs_vfs_rename(struct mnt_idmap *idmap,
 			   struct inode *old_dir, struct dentry *old_dentry,
 			   struct inode *new_dir, struct dentry *new_dentry,
 			   unsigned int flags);
-extern struct inode *v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid,
-						bool new);
+extern struct inode *v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid);
 extern const struct inode_operations v9fs_dir_inode_operations_dotl;
 extern const struct inode_operations v9fs_file_inode_operations_dotl;
 extern const struct inode_operations v9fs_symlink_inode_operations_dotl;
 extern const struct netfs_request_ops v9fs_req_ops;
 extern struct inode *v9fs_fid_iget_dotl(struct super_block *sb,
-						struct p9_fid *fid, bool new);
+					struct p9_fid *fid);
 
 /* other default globals */
 #define V9FS_PORT	564
@@ -225,12 +224,12 @@ static inline int v9fs_proto_dotl(struct v9fs_session_info *v9ses)
  */
 static inline struct inode *
 v9fs_get_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
-			struct super_block *sb, bool new)
+			struct super_block *sb)
 {
 	if (v9fs_proto_dotl(v9ses))
-		return v9fs_fid_iget_dotl(sb, fid, new);
+		return v9fs_fid_iget_dotl(sb, fid);
 	else
-		return v9fs_fid_iget(sb, fid, new);
+		return v9fs_fid_iget(sb, fid);
 }
 
 #endif
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index effb3aa1f3ed..5e05ec7af42e 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -366,8 +366,7 @@ void v9fs_evict_inode(struct inode *inode)
 		clear_inode(inode);
 }
 
-struct inode *
-v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid, bool new)
+struct inode *v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid)
 {
 	dev_t rdev;
 	int retval;
@@ -379,18 +378,8 @@ v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid, bool new)
 	inode = iget_locked(sb, QID2INO(&fid->qid));
 	if (unlikely(!inode))
 		return ERR_PTR(-ENOMEM);
-	if (!(inode->i_state & I_NEW)) {
-		if (!new) {
-			goto done;
-		} else {
-			p9_debug(P9_DEBUG_VFS, "WARNING: Inode collision %ld\n",
-						inode->i_ino);
-			iput(inode);
-			remove_inode_hash(inode);
-			inode = iget_locked(sb, QID2INO(&fid->qid));
-			WARN_ON(!(inode->i_state & I_NEW));
-		}
-	}
+	if (!(inode->i_state & I_NEW))
+		return inode;
 
 	/*
 	 * initialize the inode with the stat info
@@ -414,11 +403,11 @@ v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid, bool new)
 	v9fs_set_netfs_context(inode);
 	v9fs_cache_inode_get_cookie(inode);
 	unlock_new_inode(inode);
-done:
 	return inode;
 error:
 	iget_failed(inode);
 	return ERR_PTR(retval);
+
 }
 
 /**
@@ -450,15 +439,8 @@ static int v9fs_at_to_dotl_flags(int flags)
  */
 static void v9fs_dec_count(struct inode *inode)
 {
-	if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2) {
-		if (inode->i_nlink) {
-			drop_nlink(inode);
-		} else {
-			p9_debug(P9_DEBUG_VFS,
-						"WARNING: unexpected i_nlink zero %d inode %ld\n",
-						inode->i_nlink, inode->i_ino);
-		}
-	}
+	if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2)
+		drop_nlink(inode);
 }
 
 /**
@@ -509,9 +491,6 @@ static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
 		} else
 			v9fs_dec_count(inode);
 
-		if (inode->i_nlink <= 0)	/* no more refs unhash it */
-			remove_inode_hash(inode);
-
 		v9fs_invalidate_inode_attr(inode);
 		v9fs_invalidate_inode_attr(dir);
 
@@ -577,7 +556,7 @@ v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
 		/*
 		 * instantiate inode and assign the unopened fid to the dentry
 		 */
-		inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb, true);
+		inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
 		if (IS_ERR(inode)) {
 			err = PTR_ERR(inode);
 			p9_debug(P9_DEBUG_VFS,
@@ -706,7 +685,7 @@ struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
 	else if (IS_ERR(fid))
 		inode = ERR_CAST(fid);
 	else
-		inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb, false);
+		inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
 	/*
 	 * If we had a rename on the server and a parallel lookup
 	 * for the new name, then make sure we instantiate with
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index c61b97bd13b9..55dde186041a 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -52,10 +52,7 @@ static kgid_t v9fs_get_fsgid_for_create(struct inode *dir_inode)
 	return current_fsgid();
 }
 
-
-
-struct inode *
-v9fs_fid_iget_dotl(struct super_block *sb, struct p9_fid *fid, bool new)
+struct inode *v9fs_fid_iget_dotl(struct super_block *sb, struct p9_fid *fid)
 {
 	int retval;
 	struct inode *inode;
@@ -65,18 +62,8 @@ v9fs_fid_iget_dotl(struct super_block *sb, struct p9_fid *fid, bool new)
 	inode = iget_locked(sb, QID2INO(&fid->qid));
 	if (unlikely(!inode))
 		return ERR_PTR(-ENOMEM);
-	if (!(inode->i_state & I_NEW)) {
-		if (!new) {
-			goto done;
-		} else { /* deal with race condition in inode number reuse */
-			p9_debug(P9_DEBUG_ERROR, "WARNING: Inode collision %lx\n",
-						inode->i_ino);
-			iput(inode);
-			remove_inode_hash(inode);
-			inode = iget_locked(sb, QID2INO(&fid->qid));
-			WARN_ON(!(inode->i_state & I_NEW));
-		}
-	}
+	if (!(inode->i_state & I_NEW))
+		return inode;
 
 	/*
 	 * initialize the inode with the stat info
@@ -103,11 +90,12 @@ v9fs_fid_iget_dotl(struct super_block *sb, struct p9_fid *fid, bool new)
 		goto error;
 
 	unlock_new_inode(inode);
-done:
+
 	return inode;
 error:
 	iget_failed(inode);
 	return ERR_PTR(retval);
+
 }
 
 struct dotl_openflag_map {
@@ -259,7 +247,7 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
 		goto out;
 	}
-	inode = v9fs_fid_iget_dotl(dir->i_sb, fid, true);
+	inode = v9fs_fid_iget_dotl(dir->i_sb, fid);
 	if (IS_ERR(inode)) {
 		err = PTR_ERR(inode);
 		p9_debug(P9_DEBUG_VFS, "inode creation failed %d\n", err);
@@ -352,7 +340,7 @@ static int v9fs_vfs_mkdir_dotl(struct mnt_idmap *idmap,
 	}
 
 	/* instantiate inode and assign the unopened fid to the dentry */
-	inode = v9fs_fid_iget_dotl(dir->i_sb, fid, true);
+	inode = v9fs_fid_iget_dotl(dir->i_sb, fid);
 	if (IS_ERR(inode)) {
 		err = PTR_ERR(inode);
 		p9_debug(P9_DEBUG_VFS, "inode creation failed %d\n",
@@ -788,7 +776,7 @@ v9fs_vfs_mknod_dotl(struct mnt_idmap *idmap, struct inode *dir,
 			 err);
 		goto error;
 	}
-	inode = v9fs_fid_iget_dotl(dir->i_sb, fid, true);
+	inode = v9fs_fid_iget_dotl(dir->i_sb, fid);
 	if (IS_ERR(inode)) {
 		err = PTR_ERR(inode);
 		p9_debug(P9_DEBUG_VFS, "inode creation failed %d\n",
diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index f52fdf42945c..55e67e36ae68 100644
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -139,7 +139,7 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
 	else
 		sb->s_d_op = &v9fs_dentry_operations;
 
-	inode = v9fs_get_inode_from_fid(v9ses, fid, sb, true);
+	inode = v9fs_get_inode_from_fid(v9ses, fid, sb);
 	if (IS_ERR(inode)) {
 		retval = PTR_ERR(inode);
 		goto release_sb;