From a683a5b2ba23598ad343e5ec10a4ef4077497fc9 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 2 Jul 2025 06:34:37 +0100 Subject: fold fs_struct->{lock,seq} into a seqlock The combination of spinlock_t lock and seqcount_spinlock_t seq in struct fs_struct is an open-coded seqlock_t (see linux/seqlock_types.h). Combine and switch to equivalent seqlock_t primitives. AFAICS, that does end up with the same sequence of underlying operations in all cases. While we are at it, get_fs_pwd() is open-coded verbatim in get_path_from_fd(); rather than applying conversion to it, replace with the call of get_fs_pwd() there. Not worth splitting the commit for that, IMO... A bit of historical background - conversion of seqlock_t to use of seqcount_spinlock_t happened several months after the same had been done to struct fs_struct; switching fs_struct to seqlock_t could've been done immediately after that, but it looks like nobody had gotten around to that until now. Signed-off-by: Al Viro Link: https://lore.kernel.org/20250702053437.GC1880847@ZenIV Acked-by: Ahmed S. Darwish Acked-by: Peter Zijlstra (Intel) Reviewed-by: Christian Brauner Signed-off-by: Christian Brauner --- include/linux/fs_struct.h | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'include/linux/fs_struct.h') diff --git a/include/linux/fs_struct.h b/include/linux/fs_struct.h index 783b48dedb72..baf200ab5c77 100644 --- a/include/linux/fs_struct.h +++ b/include/linux/fs_struct.h @@ -8,8 +8,7 @@ struct fs_struct { int users; - spinlock_t lock; - seqcount_spinlock_t seq; + seqlock_t seq; int umask; int in_exec; struct path root, pwd; @@ -26,18 +25,18 @@ extern int unshare_fs_struct(void); static inline void get_fs_root(struct fs_struct *fs, struct path *root) { - spin_lock(&fs->lock); + read_seqlock_excl(&fs->seq); *root = fs->root; path_get(root); - spin_unlock(&fs->lock); + read_sequnlock_excl(&fs->seq); } static inline void get_fs_pwd(struct fs_struct *fs, struct path *pwd) { - spin_lock(&fs->lock); + read_seqlock_excl(&fs->seq); *pwd = fs->pwd; path_get(pwd); - spin_unlock(&fs->lock); + read_sequnlock_excl(&fs->seq); } extern bool current_chrooted(void); -- cgit v1.2.3