linux-kernel - [PATCH RFC 2/2] pidfs: remove 32bit inode number handling

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Message-ID: <20241128-work-pidfs-v1-2-80f267639d98@kernel.org>
Date: Thu, 28 Nov 2024 13:33:38 +0100
From: Christian Brauner <brauner@...nel.org>
To: Erin Shepherd <erin.shepherd@....eu>,
	Amir Goldstein <amir73il@...il.com>,
	Jeff Layton <jlayton@...nel.org>
Cc: Christian Brauner <brauner@...nel.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Jan Kara <jack@...e.cz>,
	Chuck Lever <chuck.lever@...cle.com>,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-nfs@...r.kernel.org
Subject: [PATCH RFC 2/2] pidfs: remove 32bit inode number handling

Now that we have a unified inode number handling model remove the custom
ida-based allocation for 32bit.

Signed-off-by: Christian Brauner <brauner@...nel.org>
---
 fs/pidfs.c | 46 +++++-----------------------------------------
 1 file changed, 5 insertions(+), 41 deletions(-)

diff --git a/fs/pidfs.c b/fs/pidfs.c
index 09a0c8ac805301927a94758b3f7d1e513826daf9..334d2fc3f01ee6f219dc3e52309bfe00726885ca 100644
--- a/fs/pidfs.c
+++ b/fs/pidfs.c
@@ -400,40 +400,6 @@ struct pid *pidfd_pid(const struct file *file)
 
 static struct vfsmount *pidfs_mnt __ro_after_init;
 
-#if BITS_PER_LONG == 32
-/*
- * Provide a fallback mechanism for 32-bit systems so processes remain
- * reliably comparable by inode number even on those systems.
- */
-static DEFINE_IDA(pidfd_inum_ida);
-
-static int pidfs_inum(struct pid *pid, unsigned long *ino)
-{
-	int ret;
-
-	ret = ida_alloc_range(&pidfd_inum_ida, RESERVED_PIDS + 1,
-			      UINT_MAX, GFP_ATOMIC);
-	if (ret < 0)
-		return -ENOSPC;
-
-	*ino = ret;
-	return 0;
-}
-
-static inline void pidfs_free_inum(unsigned long ino)
-{
-	if (ino > 0)
-		ida_free(&pidfd_inum_ida, ino);
-}
-#else
-static inline int pidfs_inum(struct pid *pid, unsigned long *ino)
-{
-	*ino = pid->ino;
-	return 0;
-}
-#define pidfs_free_inum(ino) ((void)(ino))
-#endif
-
 /*
  * The vfs falls back to simple_setattr() if i_op->setattr() isn't
  * implemented. Let's reject it completely until we have a clean
@@ -485,7 +451,6 @@ static void pidfs_evict_inode(struct inode *inode)
 
 	clear_inode(inode);
 	put_pid(pid);
-	pidfs_free_inum(inode->i_ino);
 }
 
 static const struct super_operations pidfs_sops = {
@@ -511,17 +476,16 @@ static const struct dentry_operations pidfs_dentry_operations = {
 
 static int pidfs_init_inode(struct inode *inode, void *data)
 {
+	struct pid *pid = data;
+
 	inode->i_private = data;
 	inode->i_flags |= S_PRIVATE;
 	inode->i_mode |= S_IRWXU;
 	inode->i_op = &pidfs_inode_operations;
 	inode->i_fop = &pidfs_file_operations;
-	/*
-	 * Inode numbering for pidfs start at RESERVED_PIDS + 1. This
-	 * avoids collisions with the root inode which is 1 for pseudo
-	 * filesystems.
-	 */
-	return pidfs_inum(data, &inode->i_ino);
+	inode->i_ino = pidfs_ino(pid->ino);
+	inode->i_generation = pidfs_gen(pid->ino);
+	return 0;
 }
 
 static void pidfs_put_data(void *data)

-- 
2.45.2