From 5a66847e4471be8250da9fadb8d400f1947b9872 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Mon, 11 Jun 2018 12:03:31 -0400 Subject: fs: Convert unnamed_dev_ida to new API The new API is much easier for this user. Also add kerneldoc for get_anon_bdev(). Signed-off-by: Matthew Wilcox --- fs/super.c | 67 ++++++++++++++++++++++---------------------------------------- 1 file changed, 24 insertions(+), 43 deletions(-) (limited to 'fs/super.c') diff --git a/fs/super.c b/fs/super.c index 50728d9c1a05..5a1b22af82db 100644 --- a/fs/super.c +++ b/fs/super.c @@ -978,58 +978,42 @@ void emergency_thaw_all(void) } } -/* - * Unnamed block devices are dummy devices used by virtual - * filesystems which don't use real block-devices. -- jrs - */ - static DEFINE_IDA(unnamed_dev_ida); -static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */ -/* Many userspace utilities consider an FSID of 0 invalid. - * Always return at least 1 from get_anon_bdev. - */ -static int unnamed_dev_start = 1; +/** + * get_anon_bdev - Allocate a block device for filesystems which don't have one. + * @p: Pointer to a dev_t. + * + * Filesystems which don't use real block devices can call this function + * to allocate a virtual block device. + * + * Context: Any context. Frequently called while holding sb_lock. + * Return: 0 on success, -EMFILE if there are no anonymous bdevs left + * or -ENOMEM if memory allocation failed. + */ int get_anon_bdev(dev_t *p) { int dev; - int error; - retry: - if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0) - return -ENOMEM; - spin_lock(&unnamed_dev_lock); - error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev); - if (!error) - unnamed_dev_start = dev + 1; - spin_unlock(&unnamed_dev_lock); - if (error == -EAGAIN) - /* We raced and lost with another CPU. */ - goto retry; - else if (error) - return -EAGAIN; - - if (dev >= (1 << MINORBITS)) { - spin_lock(&unnamed_dev_lock); - ida_remove(&unnamed_dev_ida, dev); - if (unnamed_dev_start > dev) - unnamed_dev_start = dev; - spin_unlock(&unnamed_dev_lock); - return -EMFILE; - } - *p = MKDEV(0, dev & MINORMASK); + /* + * Many userspace utilities consider an FSID of 0 invalid. + * Always return at least 1 from get_anon_bdev. + */ + dev = ida_alloc_range(&unnamed_dev_ida, 1, (1 << MINORBITS) - 1, + GFP_ATOMIC); + if (dev == -ENOSPC) + dev = -EMFILE; + if (dev < 0) + return dev; + + *p = MKDEV(0, dev); return 0; } EXPORT_SYMBOL(get_anon_bdev); void free_anon_bdev(dev_t dev) { - int slot = MINOR(dev); - spin_lock(&unnamed_dev_lock); - ida_remove(&unnamed_dev_ida, slot); - if (slot < unnamed_dev_start) - unnamed_dev_start = slot; - spin_unlock(&unnamed_dev_lock); + ida_free(&unnamed_dev_ida, MINOR(dev)); } EXPORT_SYMBOL(free_anon_bdev); @@ -1037,7 +1021,6 @@ int set_anon_super(struct super_block *s, void *data) { return get_anon_bdev(&s->s_dev); } - EXPORT_SYMBOL(set_anon_super); void kill_anon_super(struct super_block *sb) @@ -1046,7 +1029,6 @@ void kill_anon_super(struct super_block *sb) generic_shutdown_super(sb); free_anon_bdev(dev); } - EXPORT_SYMBOL(kill_anon_super); void kill_litter_super(struct super_block *sb) @@ -1055,7 +1037,6 @@ void kill_litter_super(struct super_block *sb) d_genocide(sb->s_root); kill_anon_super(sb); } - EXPORT_SYMBOL(kill_litter_super); static int ns_test_super(struct super_block *sb, void *data) -- cgit v1.2.3