super: use locking helpers
Replace the open-coded {down,up}_{read,write}() calls with simple
wrappers. Follow-up patches will benefit from this as well.
Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230818-vfs-super-fixes-v3-v3-1-9f0b1876e46b@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
parent
e127b9bccd
commit
0ed33598dd
126
fs/super.c
126
fs/super.c
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@ -50,6 +50,42 @@ static char *sb_writers_name[SB_FREEZE_LEVELS] = {
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"sb_internal",
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};
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static inline void super_lock(struct super_block *sb, bool excl)
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{
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if (excl)
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down_write(&sb->s_umount);
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else
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down_read(&sb->s_umount);
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}
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static inline void super_unlock(struct super_block *sb, bool excl)
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{
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if (excl)
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up_write(&sb->s_umount);
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else
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up_read(&sb->s_umount);
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}
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static inline void super_lock_excl(struct super_block *sb)
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{
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super_lock(sb, true);
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}
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static inline void super_lock_shared(struct super_block *sb)
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{
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super_lock(sb, false);
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}
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static inline void super_unlock_excl(struct super_block *sb)
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{
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super_unlock(sb, true);
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}
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static inline void super_unlock_shared(struct super_block *sb)
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{
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super_unlock(sb, false);
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}
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/*
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* One thing we have to be careful of with a per-sb shrinker is that we don't
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* drop the last active reference to the superblock from within the shrinker.
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@ -110,7 +146,7 @@ static unsigned long super_cache_scan(struct shrinker *shrink,
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freed += sb->s_op->free_cached_objects(sb, sc);
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}
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up_read(&sb->s_umount);
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super_unlock_shared(sb);
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return freed;
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}
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@ -176,7 +212,7 @@ static void destroy_unused_super(struct super_block *s)
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{
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if (!s)
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return;
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up_write(&s->s_umount);
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super_unlock_excl(s);
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list_lru_destroy(&s->s_dentry_lru);
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list_lru_destroy(&s->s_inode_lru);
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security_sb_free(s);
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@ -340,7 +376,7 @@ void deactivate_locked_super(struct super_block *s)
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put_filesystem(fs);
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put_super(s);
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} else {
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up_write(&s->s_umount);
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super_unlock_excl(s);
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}
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}
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@ -357,7 +393,7 @@ EXPORT_SYMBOL(deactivate_locked_super);
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void deactivate_super(struct super_block *s)
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{
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if (!atomic_add_unless(&s->s_active, -1, 1)) {
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down_write(&s->s_umount);
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super_lock_excl(s);
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deactivate_locked_super(s);
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}
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}
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@ -381,12 +417,12 @@ static int grab_super(struct super_block *s) __releases(sb_lock)
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{
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s->s_count++;
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spin_unlock(&sb_lock);
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down_write(&s->s_umount);
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super_lock_excl(s);
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if ((s->s_flags & SB_BORN) && atomic_inc_not_zero(&s->s_active)) {
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put_super(s);
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return 1;
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}
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up_write(&s->s_umount);
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super_unlock_excl(s);
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put_super(s);
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return 0;
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}
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@ -414,7 +450,7 @@ bool trylock_super(struct super_block *sb)
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if (!hlist_unhashed(&sb->s_instances) &&
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sb->s_root && (sb->s_flags & SB_BORN))
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return true;
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up_read(&sb->s_umount);
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super_unlock_shared(sb);
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}
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return false;
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@ -439,13 +475,13 @@ bool trylock_super(struct super_block *sb)
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void retire_super(struct super_block *sb)
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{
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WARN_ON(!sb->s_bdev);
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down_write(&sb->s_umount);
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super_lock_excl(sb);
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if (sb->s_iflags & SB_I_PERSB_BDI) {
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bdi_unregister(sb->s_bdi);
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sb->s_iflags &= ~SB_I_PERSB_BDI;
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}
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sb->s_iflags |= SB_I_RETIRED;
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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}
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EXPORT_SYMBOL(retire_super);
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@ -521,7 +557,7 @@ void generic_shutdown_super(struct super_block *sb)
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/* should be initialized for __put_super_and_need_restart() */
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hlist_del_init(&sb->s_instances);
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spin_unlock(&sb_lock);
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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if (sb->s_bdi != &noop_backing_dev_info) {
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if (sb->s_iflags & SB_I_PERSB_BDI)
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bdi_unregister(sb->s_bdi);
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@ -685,7 +721,7 @@ EXPORT_SYMBOL(sget);
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void drop_super(struct super_block *sb)
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{
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up_read(&sb->s_umount);
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super_unlock_shared(sb);
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put_super(sb);
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}
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@ -693,7 +729,7 @@ EXPORT_SYMBOL(drop_super);
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void drop_super_exclusive(struct super_block *sb)
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{
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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put_super(sb);
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}
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EXPORT_SYMBOL(drop_super_exclusive);
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@ -739,10 +775,10 @@ void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
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sb->s_count++;
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spin_unlock(&sb_lock);
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down_read(&sb->s_umount);
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super_lock_shared(sb);
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if (sb->s_root && (sb->s_flags & SB_BORN))
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f(sb, arg);
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up_read(&sb->s_umount);
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super_unlock_shared(sb);
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spin_lock(&sb_lock);
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if (p)
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@ -773,10 +809,10 @@ void iterate_supers_type(struct file_system_type *type,
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sb->s_count++;
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spin_unlock(&sb_lock);
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down_read(&sb->s_umount);
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super_lock_shared(sb);
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if (sb->s_root && (sb->s_flags & SB_BORN))
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f(sb, arg);
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up_read(&sb->s_umount);
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super_unlock_shared(sb);
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spin_lock(&sb_lock);
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if (p)
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@ -813,7 +849,7 @@ restart:
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if (sb->s_bdev == bdev) {
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if (!grab_super(sb))
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goto restart;
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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return sb;
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}
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}
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@ -833,17 +869,11 @@ rescan:
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if (sb->s_dev == dev) {
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sb->s_count++;
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spin_unlock(&sb_lock);
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if (excl)
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down_write(&sb->s_umount);
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else
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down_read(&sb->s_umount);
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super_lock(sb, excl);
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/* still alive? */
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if (sb->s_root && (sb->s_flags & SB_BORN))
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return sb;
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if (excl)
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up_write(&sb->s_umount);
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else
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up_read(&sb->s_umount);
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super_unlock(sb, excl);
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/* nope, got unmounted */
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spin_lock(&sb_lock);
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__put_super(sb);
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@ -889,9 +919,9 @@ int reconfigure_super(struct fs_context *fc)
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if (remount_ro) {
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if (!hlist_empty(&sb->s_pins)) {
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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group_pin_kill(&sb->s_pins);
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down_write(&sb->s_umount);
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super_lock_excl(sb);
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if (!sb->s_root)
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return 0;
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if (sb->s_writers.frozen != SB_UNFROZEN)
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@ -954,7 +984,7 @@ cancel_readonly:
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static void do_emergency_remount_callback(struct super_block *sb)
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{
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down_write(&sb->s_umount);
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super_lock_excl(sb);
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if (sb->s_root && sb->s_bdev && (sb->s_flags & SB_BORN) &&
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!sb_rdonly(sb)) {
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struct fs_context *fc;
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@ -967,7 +997,7 @@ static void do_emergency_remount_callback(struct super_block *sb)
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put_fs_context(fc);
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}
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}
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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}
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static void do_emergency_remount(struct work_struct *work)
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@ -990,12 +1020,12 @@ void emergency_remount(void)
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static void do_thaw_all_callback(struct super_block *sb)
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{
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down_write(&sb->s_umount);
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super_lock_excl(sb);
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if (sb->s_root && sb->s_flags & SB_BORN) {
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emergency_thaw_bdev(sb);
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thaw_super_locked(sb);
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} else {
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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}
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}
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@ -1182,10 +1212,10 @@ EXPORT_SYMBOL(get_tree_keyed);
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*/
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static bool lock_active_super(struct super_block *sb)
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{
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down_read(&sb->s_umount);
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super_lock_shared(sb);
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if (!sb->s_root ||
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(sb->s_flags & (SB_ACTIVE | SB_BORN)) != (SB_ACTIVE | SB_BORN)) {
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up_read(&sb->s_umount);
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super_unlock_shared(sb);
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return false;
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}
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return true;
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@ -1208,7 +1238,7 @@ static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise)
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if (sb->s_op->shutdown)
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sb->s_op->shutdown(sb);
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up_read(&sb->s_umount);
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super_unlock_shared(sb);
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}
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static void fs_bdev_sync(struct block_device *bdev)
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@ -1220,7 +1250,7 @@ static void fs_bdev_sync(struct block_device *bdev)
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if (!lock_active_super(sb))
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return;
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sync_filesystem(sb);
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up_read(&sb->s_umount);
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super_unlock_shared(sb);
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}
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const struct blk_holder_ops fs_holder_ops = {
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@ -1342,9 +1372,9 @@ int get_tree_bdev(struct fs_context *fc,
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* bdev_mark_dead()). It is safe because we have active sb
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* reference and SB_BORN is not set yet.
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*/
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up_write(&s->s_umount);
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super_unlock_excl(s);
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error = setup_bdev_super(s, fc->sb_flags, fc);
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down_write(&s->s_umount);
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super_lock_excl(s);
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if (!error)
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error = fill_super(s, fc);
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if (error) {
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@ -1394,9 +1424,9 @@ struct dentry *mount_bdev(struct file_system_type *fs_type,
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* bdev_mark_dead()). It is safe because we have active sb
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* reference and SB_BORN is not set yet.
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*/
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up_write(&s->s_umount);
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super_unlock_excl(s);
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error = setup_bdev_super(s, flags, NULL);
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down_write(&s->s_umount);
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super_lock_excl(s);
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if (!error)
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error = fill_super(s, data, flags & SB_SILENT ? 1 : 0);
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if (error) {
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@ -1685,29 +1715,29 @@ int freeze_super(struct super_block *sb)
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int ret;
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atomic_inc(&sb->s_active);
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down_write(&sb->s_umount);
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super_lock_excl(sb);
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if (sb->s_writers.frozen != SB_UNFROZEN) {
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deactivate_locked_super(sb);
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return -EBUSY;
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}
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if (!(sb->s_flags & SB_BORN)) {
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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return 0; /* sic - it's "nothing to do" */
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}
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if (sb_rdonly(sb)) {
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/* Nothing to do really... */
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sb->s_writers.frozen = SB_FREEZE_COMPLETE;
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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return 0;
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}
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sb->s_writers.frozen = SB_FREEZE_WRITE;
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/* Release s_umount to preserve sb_start_write -> s_umount ordering */
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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sb_wait_write(sb, SB_FREEZE_WRITE);
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down_write(&sb->s_umount);
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super_lock_excl(sb);
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/* Now we go and block page faults... */
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sb->s_writers.frozen = SB_FREEZE_PAGEFAULT;
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@ -1743,7 +1773,7 @@ int freeze_super(struct super_block *sb)
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*/
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sb->s_writers.frozen = SB_FREEZE_COMPLETE;
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lockdep_sb_freeze_release(sb);
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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return 0;
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}
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EXPORT_SYMBOL(freeze_super);
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@ -1753,7 +1783,7 @@ static int thaw_super_locked(struct super_block *sb)
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int error;
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if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) {
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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return -EINVAL;
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}
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@ -1770,7 +1800,7 @@ static int thaw_super_locked(struct super_block *sb)
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printk(KERN_ERR
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"VFS:Filesystem thaw failed\n");
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lockdep_sb_freeze_release(sb);
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up_write(&sb->s_umount);
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super_unlock_excl(sb);
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return error;
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}
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}
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@ -1790,7 +1820,7 @@ out:
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*/
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int thaw_super(struct super_block *sb)
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{
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down_write(&sb->s_umount);
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super_lock_excl(sb);
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return thaw_super_locked(sb);
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}
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EXPORT_SYMBOL(thaw_super);
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