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file: massage cleanup of files that failed to open

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A file that has never gotten FMODE_OPENED will never have RCU-accessed
references, its final fput() is equivalent to file_free() and if it
doesn't have FMODE_BACKING either, it can be done from any context and
won't need task_work treatment.

Now that we have SLAB_TYPESAFE_BY_RCU we can simplify this and have
other callers benefit. All of that can be achieved easier is to make
fput() recoginze that case and call file_free() directly.

No need to introduce a special primitive for that. It also allowed
things like failing dentry_open() could benefit from that as well.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[Christian Brauner <brauner@kernel.org>: massage commit message]
Link: https://lore.kernel.org/r/20231126020834.GC38156@ZenIV
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Al Viro 2023-11-26 02:08:34 +00:00 committed by Christian Brauner
parent b85ea95d08
commit 7cb537b6f6
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GPG key ID: 91C61BC06578DCA2
3 changed files with 5 additions and 17 deletions
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16
fs/file_table.c
View file

@ -75,18 +75,6 @@ static inline void file_free(struct file *f)
}
}
void release_empty_file(struct file *f)
{
WARN_ON_ONCE(f->f_mode & (FMODE_BACKING | FMODE_OPENED));
if (atomic_long_dec_and_test(&f->f_count)) {
security_file_free(f);
put_cred(f->f_cred);
if (likely(!(f->f_mode & FMODE_NOACCOUNT)))
percpu_counter_dec(&nr_files);
kmem_cache_free(filp_cachep, f);
}
}
/*
* Return the total number of open files in the system
*/
@ -445,6 +433,10 @@ void fput(struct file *file)
if (atomic_long_dec_and_test(&file->f_count)) {
struct task_struct *task = current;
if (unlikely(!(file->f_mode & (FMODE_BACKING | FMODE_OPENED)))) {
file_free(file);
return;
}
if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
init_task_work(&file->f_rcuhead, ____fput);
if (!task_work_add(task, &file->f_rcuhead, TWA_RESUME))

1
fs/internal.h
View file

@ -94,7 +94,6 @@ extern void chroot_fs_refs(const struct path *, const struct path *);
struct file *alloc_empty_file(int flags, const struct cred *cred);
struct file *alloc_empty_file_noaccount(int flags, const struct cred *cred);
struct file *alloc_empty_backing_file(int flags, const struct cred *cred);
void release_empty_file(struct file *f);
static inline void file_put_write_access(struct file *file)
{

5
fs/namei.c
View file

@ -3785,10 +3785,7 @@ static struct file *path_openat(struct nameidata *nd,
WARN_ON(1);
error = -EINVAL;
}
if (unlikely(file->f_mode & FMODE_OPENED))
fput(file);
else
release_empty_file(file);
fput(file);
if (error == -EOPENSTALE) {
if (flags & LOOKUP_RCU)
error = -ECHILD;