From f378ec4eec8b7e607dbc0112913fd3d5d84eb1b8 Mon Sep 17 00:00:00 2001
From: Mateusz Guzik <mjguzik@gmail.com>
Date: Thu, 27 Jun 2024 18:11:52 +0200
Subject: [PATCH] vfs: rename parent_ino to d_parent_ino and make it use RCU
The routine is used by procfs through dir_emit_dots.
The combined RCU and lock fallback implementation is too big for an
inline. Given that the routine takes a dentry argument fs/dcache.c seems
like the place to put it in.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240627161152.802567-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
---
fs/dcache.c | 28 ++++++++++++++++++++++++++++
fs/f2fs/file.c | 2 +-
fs/hfsplus/ioctl.c | 4 ++--
include/linux/dcache.h | 2 ++
include/linux/fs.h | 16 +---------------
5 files changed, 34 insertions(+), 18 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 58b89c9e9b0c8..68e843e78337d 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3099,6 +3099,34 @@ void d_tmpfile(struct file *file, struct inode *inode)
}
EXPORT_SYMBOL(d_tmpfile);
+/*
+ * Obtain inode number of the parent dentry.
+ */
+ino_t d_parent_ino(struct dentry *dentry)
+{
+ struct dentry *parent;
+ struct inode *iparent;
+ unsigned seq;
+ ino_t ret;
+
+ scoped_guard(rcu) {
+ seq = raw_seqcount_begin(&dentry->d_seq);
+ parent = READ_ONCE(dentry->d_parent);
+ iparent = d_inode_rcu(parent);
+ if (likely(iparent)) {
+ ret = iparent->i_ino;
+ if (!read_seqcount_retry(&dentry->d_seq, seq))
+ return ret;
+ }
+ }
+
+ spin_lock(&dentry->d_lock);
+ ret = dentry->d_parent->d_inode->i_ino;
+ spin_unlock(&dentry->d_lock);
+ return ret;
+}
+EXPORT_SYMBOL(d_parent_ino);
+
static __initdata unsigned long dhash_entries;
static int __init set_dhash_entries(char *str)
{
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 7a23434963d17..c1ad9b278c477 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -185,7 +185,7 @@ static int get_parent_ino(struct inode *inode, nid_t *pino)
if (!dentry)
return 0;
- *pino = parent_ino(dentry);
+ *pino = d_parent_ino(dentry);
dput(dentry);
return 1;
}
diff --git a/fs/hfsplus/ioctl.c b/fs/hfsplus/ioctl.c
index 5661a2e24d036..40d04dba13ac8 100644
--- a/fs/hfsplus/ioctl.c
+++ b/fs/hfsplus/ioctl.c
@@ -40,7 +40,7 @@ static int hfsplus_ioctl_bless(struct file *file, int __user *user_flags)
/* Directory containing the bootable system */
vh->finder_info[0] = bvh->finder_info[0] =
- cpu_to_be32(parent_ino(dentry));
+ cpu_to_be32(d_parent_ino(dentry));
/*
* Bootloader. Just using the inode here breaks in the case of
@@ -51,7 +51,7 @@ static int hfsplus_ioctl_bless(struct file *file, int __user *user_flags)
/* Per spec, the OS X system folder - same as finder_info[0] here */
vh->finder_info[5] = bvh->finder_info[5] =
- cpu_to_be32(parent_ino(dentry));
+ cpu_to_be32(d_parent_ino(dentry));
mutex_unlock(&sbi->vh_mutex);
return 0;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index bf53e3894aae3..ea58843942b96 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -278,6 +278,8 @@ static inline unsigned d_count(const struct dentry *dentry)
return dentry->d_lockref.count;
}
+ino_t d_parent_ino(struct dentry *dentry);
+
/*
* helper function for dentry_operations.d_dname() members
*/
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5ff362277834c..2fa06a4d197a7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3454,20 +3454,6 @@ static inline int kiocb_set_rw_flags(struct kiocb *ki, rwf_t flags)
return 0;
}
-static inline ino_t parent_ino(struct dentry *dentry)
-{
- ino_t res;
-
- /*
- * Don't strictly need d_lock here? If the parent ino could change
- * then surely we'd have a deeper race in the caller?
- */
- spin_lock(&dentry->d_lock);
- res = dentry->d_parent->d_inode->i_ino;
- spin_unlock(&dentry->d_lock);
- return res;
-}
-
/* Transaction based IO helpers */
/*
@@ -3592,7 +3578,7 @@ static inline bool dir_emit_dot(struct file *file, struct dir_context *ctx)
static inline bool dir_emit_dotdot(struct file *file, struct dir_context *ctx)
{
return ctx->actor(ctx, "..", 2, ctx->pos,
- parent_ino(file->f_path.dentry), DT_DIR);
+ d_parent_ino(file->f_path.dentry), DT_DIR);
}
static inline bool dir_emit_dots(struct file *file, struct dir_context *ctx)
{
--
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