From 5bd91b14b2a9cbf667db3d240c93709c0b5e6815 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 15 Apr 2021 17:30:21 +0800 Subject: [PATCH] fs: add fget_many() and fput_many() mainline inclusion from mainline-5.1-rc1 commit 091141a42e15fe47ada737f3996b317072afcefb category: feature bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=27 CVE: NA --------------------------- Some uses cases repeatedly get and put references to the same file, but the only exposed interface is doing these one at the time. As each of these entail an atomic inc or dec on a shared structure, that cost can add up. Add fget_many(), which works just like fget(), except it takes an argument for how many references to get on the file. Ditto fput_many(), which can drop an arbitrary number of references to a file. Reviewed-by: Hannes Reinecke Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe Signed-off-by: Zhihao Cheng Signed-off-by: yangerkun Reviewed-by: zhangyi (F) Signed-off-by: Cheng Jian --- fs/file.c | 15 ++++++++++----- fs/file_table.c | 9 +++++++-- include/linux/file.h | 2 ++ include/linux/fs.h | 4 +++- 4 files changed, 22 insertions(+), 8 deletions(-) diff --git a/fs/file.c b/fs/file.c index 6dd55640e91f..90818a3907c5 100644 --- a/fs/file.c +++ b/fs/file.c @@ -720,7 +720,7 @@ void do_close_on_exec(struct files_struct *files) spin_unlock(&files->file_lock); } -static struct file *__fget(unsigned int fd, fmode_t mask) +static struct file *__fget(unsigned int fd, fmode_t mask, unsigned int refs) { struct files_struct *files = current->files; struct file *file; @@ -735,7 +735,7 @@ static struct file *__fget(unsigned int fd, fmode_t mask) */ if (file->f_mode & mask) file = NULL; - else if (!get_file_rcu(file)) + else if (!get_file_rcu_many(file, refs)) goto loop; } rcu_read_unlock(); @@ -743,15 +743,20 @@ static struct file *__fget(unsigned int fd, fmode_t mask) return file; } +struct file *fget_many(unsigned int fd, unsigned int refs) +{ + return __fget(fd, FMODE_PATH, refs); +} + struct file *fget(unsigned int fd) { - return __fget(fd, FMODE_PATH); + return __fget(fd, FMODE_PATH, 1); } EXPORT_SYMBOL(fget); struct file *fget_raw(unsigned int fd) { - return __fget(fd, 0); + return __fget(fd, 0, 1); } EXPORT_SYMBOL(fget_raw); @@ -782,7 +787,7 @@ static unsigned long __fget_light(unsigned int fd, fmode_t mask) return 0; return (unsigned long)file; } else { - file = __fget(fd, mask); + file = __fget(fd, mask, 1); if (!file) return 0; return FDPUT_FPUT | (unsigned long)file; diff --git a/fs/file_table.c b/fs/file_table.c index e49af4caf15d..6a715639728d 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -326,9 +326,9 @@ void flush_delayed_fput(void) static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput); -void fput(struct file *file) +void fput_many(struct file *file, unsigned int refs) { - if (atomic_long_dec_and_test(&file->f_count)) { + if (atomic_long_sub_and_test(refs, &file->f_count)) { struct task_struct *task = current; if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) { @@ -347,6 +347,11 @@ void fput(struct file *file) } } +void fput(struct file *file) +{ + fput_many(file, 1); +} + /* * synchronous analog of fput(); for kernel threads that might be needed * in some umount() (and thus can't use flush_delayed_fput() without diff --git a/include/linux/file.h b/include/linux/file.h index 6b2fb032416c..3fcddff56bc4 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -13,6 +13,7 @@ struct file; extern void fput(struct file *); +extern void fput_many(struct file *, unsigned int); struct file_operations; struct vfsmount; @@ -44,6 +45,7 @@ static inline void fdput(struct fd fd) } extern struct file *fget(unsigned int fd); +extern struct file *fget_many(unsigned int fd, unsigned int refs); extern struct file *fget_raw(unsigned int fd); extern unsigned long __fdget(unsigned int fd); extern unsigned long __fdget_raw(unsigned int fd); diff --git a/include/linux/fs.h b/include/linux/fs.h index 2c23ead8a698..db7dd25ce645 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -968,7 +968,9 @@ static inline struct file *get_file(struct file *f) atomic_long_inc(&f->f_count); return f; } -#define get_file_rcu(x) atomic_long_inc_not_zero(&(x)->f_count) +#define get_file_rcu_many(x, cnt) \ + atomic_long_add_unless(&(x)->f_count, (cnt), 0) +#define get_file_rcu(x) get_file_rcu_many((x), 1) #define fput_atomic(x) atomic_long_add_unless(&(x)->f_count, -1, 1) #define file_count(x) atomic_long_read(&(x)->f_count) -- GitLab