| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20250328-work-freeze-v1-5-a2c3a6b0e7a6@kernel.org>
Date: Fri, 28 Mar 2025 17:15:57 +0100
From: Christian Brauner <brauner@...nel.org>
To: linux-fsdevel@...r.kernel.org,
jack@...e.cz
Cc: Christian Brauner <brauner@...nel.org>,
linux-kernel@...r.kernel.org,
James Bottomley <James.Bottomley@...senpartnership.com>,
mcgrof@...nel.org,
hch@...radead.org,
david@...morbit.com,
rafael@...nel.org,
djwong@...nel.org,
pavel@...nel.org,
peterz@...radead.org,
mingo@...hat.com,
will@...nel.org,
boqun.feng@...il.com
Subject: [PATCH 5/6] super: use common iterator (Part 2)
Use a common iterator for all callbacks. We could go for something even
more elaborate (advance step-by-step similar to iov_iter) but I really
don't think this is warranted.
Signed-off-by: Christian Brauner <brauner@...nel.org>
---
fs/super.c | 76 +++++++++++++++++++++++++++++++++++++++++++++---------
include/linux/fs.h | 6 +----
2 files changed, 65 insertions(+), 17 deletions(-)
diff --git a/fs/super.c b/fs/super.c
index 0dd208804a74..58c95210e66c 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -887,24 +887,71 @@ void drop_super_exclusive(struct super_block *sb)
}
EXPORT_SYMBOL(drop_super_exclusive);
-void __iterate_supers(void (*f)(struct super_block *, void *), void *arg, bool excl)
+enum super_iter_flags_t {
+ SUPER_ITER_EXCL = (1U << 0),
+ SUPER_ITER_GRAB = (1U << 1) | SUPER_ITER_EXCL,
+ SUPER_ITER_REVERSE = (1U << 2),
+};
+
+static inline struct super_block *first_super(enum super_iter_flags_t flags)
+{
+ if (flags & SUPER_ITER_REVERSE)
+ return list_last_entry(&super_blocks, struct super_block, s_list);
+ return list_first_entry(&super_blocks, struct super_block, s_list);
+}
+
+static inline struct super_block *next_super(struct super_block *sb,
+ enum super_iter_flags_t flags)
+{
+ if (flags & SUPER_ITER_REVERSE)
+ return list_prev_entry(sb, s_list);
+ return list_next_entry(sb, s_list);
+}
+
+static inline void super_cb_locked(struct super_block *sb,
+ void (*f)(struct super_block *, void *),
+ void *arg, bool excl)
+{
+ if (super_lock(sb, excl)) {
+ f(sb, arg);
+ super_unlock(sb, excl);
+ }
+}
+
+static inline void super_cb_grabbed(struct super_block *sb,
+ void (*f)(struct super_block *, void *),
+ void *arg)
+{
+ if (super_lock_excl(sb)) {
+ bool active = atomic_inc_not_zero(&sb->s_active);
+ super_unlock_excl(sb);
+ if (active)
+ f(sb, arg);
+ deactivate_super(sb);
+ }
+}
+
+#define invalid_super list_entry_is_head
+
+static void __iterate_supers(void (*f)(struct super_block *, void *), void *arg,
+ enum super_iter_flags_t flags)
{
struct super_block *sb, *p = NULL;
+ bool excl = flags & SUPER_ITER_EXCL;
- spin_lock(&sb_lock);
- list_for_each_entry(sb, &super_blocks, s_list) {
- bool locked;
+ guard(spinlock)(&sb_lock);
+ for (sb = first_super(flags); !invalid_super(sb, &super_blocks, s_list);
+ sb = next_super(sb, flags)) {
if (super_flags(sb, SB_DYING))
continue;
sb->s_count++;
spin_unlock(&sb_lock);
- locked = super_lock(sb, excl);
- if (locked) {
- f(sb, arg);
- super_unlock(sb, excl);
- }
+ if (flags & SUPER_ITER_GRAB)
+ super_cb_grabbed(sb, f, arg);
+ else
+ super_cb_locked(sb, f, arg, excl);
spin_lock(&sb_lock);
if (p)
@@ -913,7 +960,11 @@ void __iterate_supers(void (*f)(struct super_block *, void *), void *arg, bool e
}
if (p)
__put_super(p);
- spin_unlock(&sb_lock);
+}
+
+void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
+{
+ __iterate_supers(f, arg, 0);
}
/**
@@ -1097,7 +1148,8 @@ static void do_emergency_remount_callback(struct super_block *sb, void *unused)
static void do_emergency_remount(struct work_struct *work)
{
- __iterate_supers(do_emergency_remount_callback, NULL, true);
+ __iterate_supers(do_emergency_remount_callback, NULL,
+ SUPER_ITER_EXCL | SUPER_ITER_REVERSE);
kfree(work);
printk("Emergency Remount complete\n");
}
@@ -1124,7 +1176,7 @@ static void do_thaw_all_callback(struct super_block *sb, void *unused)
static void do_thaw_all(struct work_struct *work)
{
- __iterate_supers(do_thaw_all_callback, NULL, true);
+ __iterate_supers(do_thaw_all_callback, NULL, SUPER_ITER_EXCL);
kfree(work);
printk(KERN_WARNING "Emergency Thaw complete\n");
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0351500b71d2..c475fa874055 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3515,11 +3515,7 @@ extern void put_filesystem(struct file_system_type *fs);
extern struct file_system_type *get_fs_type(const char *name);
extern void drop_super(struct super_block *sb);
extern void drop_super_exclusive(struct super_block *sb);
-void __iterate_supers(void (*f)(struct super_block *, void *), void *arg, bool excl);
-static inline void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
-{
- __iterate_supers(f, arg, false);
-}
+extern void iterate_supers(void (*f)(struct super_block *, void *), void *arg);
extern void iterate_supers_type(struct file_system_type *,
void (*)(struct super_block *, void *), void *);
--
2.47.2
Powered by blists - more mailing lists