[PATCH 4/4] fs: factor out get_fs_pwd_pool_locked() for lock-held callers

[Christian Brauner]

Extract the inner pool borrow logic from get_fs_pwd_pool() into
get_fs_pwd_pool_locked() for callers that already hold fs->seq.

Use it in copy_fs_struct() which open-coded the same pool borrow
pattern under an existing lock hold.

Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
---
 fs/fs_struct.c            |  6 +-----
 include/linux/fs_struct.h | 16 +++++++++++-----
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/fs/fs_struct.c b/fs/fs_struct.c
index 0a72fb3ea427..e1487ca6256d 100644
--- a/fs/fs_struct.c
+++ b/fs/fs_struct.c
@@ -140,11 +140,7 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old)
 		read_seqlock_excl(&old->seq);
 		fs->root = old->root;
 		path_get(&fs->root);
-		fs->pwd = old->pwd;
-		if (old->pwd_refs)
-			old->pwd_refs--;
-		else
-			path_get(&fs->pwd);
+		get_fs_pwd_pool_locked(old, &fs->pwd);
 		read_sequnlock_excl(&old->seq);
 	}
 	return fs;
diff --git a/include/linux/fs_struct.h b/include/linux/fs_struct.h
index e67d92f88605..b63003cec25f 100644
--- a/include/linux/fs_struct.h
+++ b/include/linux/fs_struct.h
@@ -42,6 +42,16 @@ static inline void get_fs_pwd(struct fs_struct *fs, struct path *pwd)
 	read_sequnlock_excl(&fs->seq);
 }
 
+/* Borrow a pwd reference from the pool. Caller must hold fs->seq. */
+static inline void get_fs_pwd_pool_locked(struct fs_struct *fs, struct path *pwd)
+{
+	*pwd = fs->pwd;
+	if (fs->pwd_refs)
+		fs->pwd_refs--;
+	else
+		path_get(pwd);
+}
+
 /*
  * Acquire a pwd reference from the pwd_refs pool, if available.
  *
@@ -54,11 +64,7 @@ static inline void get_fs_pwd(struct fs_struct *fs, struct path *pwd)
 static inline void get_fs_pwd_pool(struct fs_struct *fs, struct path *pwd)
 {
 	read_seqlock_excl(&fs->seq);
-	*pwd = fs->pwd;
-	if (fs->pwd_refs)
-		fs->pwd_refs--;
-	else
-		path_get(pwd);
+	get_fs_pwd_pool_locked(fs, pwd);
 	read_sequnlock_excl(&fs->seq);
 }
 
-- 
2.47.3


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