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fs: fix ups and tidy ups to /proc/filesystems caching

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- add missing unlocks in some corner cases
- whitespace touch ups
- s/smp_store_release/rcu_assign_pointer/ [nop, the macro expands to the same thing]
- mark file_systems_string as __read_mostly

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20260610143954.34185-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
This commit is contained in:
Mateusz Guzik
2026-06-10 16:39:54 +02:00
committed by Christian Brauner
parent 86e9d29508
commit cf30ceccfa
1 changed files with 6 additions and 8 deletions
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14
fs/filesystems.c
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@@ -54,7 +54,7 @@ struct file_systems_string {
};
static unsigned long file_systems_gen;
static struct file_systems_string __rcu *file_systems_string;
static struct file_systems_string __read_mostly __rcu *file_systems_string;
static void invalidate_filesystems_string(void);
#else
@@ -269,7 +269,7 @@ static __cold noinline int regen_filesystems_string(void)
hlist_for_each_entry_rcu(p, &file_systems, list) {
if (!(p->fs_flags & FS_REQUIRES_DEV))
newlen += strlen("nodev");
newlen += strlen("\t") + strlen(p->name) + strlen("\n");
newlen += strlen("\t") + strlen(p->name) + strlen("\n");
}
spin_unlock(&file_systems_lock);
@@ -289,6 +289,7 @@ static __cold noinline int regen_filesystems_string(void)
* Did someone beat us to it?
*/
if (old && old->gen == file_systems_gen) {
spin_unlock(&file_systems_lock);
kfree(new);
return 0;
}
@@ -297,6 +298,7 @@ static __cold noinline int regen_filesystems_string(void)
* Did the list change in the meantime?
*/
if (gen != file_systems_gen) {
spin_unlock(&file_systems_lock);
kfree(new);
goto retry;
}
@@ -321,15 +323,11 @@ static __cold noinline int regen_filesystems_string(void)
* generation above and messes it up.
*/
spin_unlock(&file_systems_lock);
if (old)
kfree_rcu(old, rcu);
kfree(new);
return -EINVAL;
}
/*
* Paired with consume fence in READ_ONCE() in filesystems_proc_show()
*/
smp_store_release(&file_systems_string, new);
rcu_assign_pointer(file_systems_string, new);
spin_unlock(&file_systems_lock);
if (old)
kfree_rcu(old, rcu);