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authorChristoph Hellwig <hch@lst.de>2015-01-14 10:42:32 +0100
committerJens Axboe <axboe@fb.com>2015-01-20 14:02:58 -0700
commitb4caecd48005fbed3949dde6c1cb233142fd69e9 (patch)
tree1fdd9b7c15568c79eb3c1ed84a39858ddbcbc88b /fs/char_dev.c
parent97b713ba3ebaa6c8d84c2c720f5468a7c6a6eb4e (diff)
downloadlinux-b4caecd48005fbed3949dde6c1cb233142fd69e9.tar.bz2
fs: introduce f_op->mmap_capabilities for nommu mmap support
Since "BDI: Provide backing device capability information [try #3]" the backing_dev_info structure also provides flags for the kind of mmap operation available in a nommu environment, which is entirely unrelated to it's original purpose. Introduce a new nommu-only file operation to provide this information to the nommu mmap code instead. Splitting this from the backing_dev_info structure allows to remove lots of backing_dev_info instance that aren't otherwise needed, and entirely gets rid of the concept of providing a backing_dev_info for a character device. It also removes the need for the mtd_inodefs filesystem. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Tejun Heo <tj@kernel.org> Acked-by: Brian Norris <computersforpeace@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'fs/char_dev.c')
-rw-r--r--fs/char_dev.c24
1 files changed, 0 insertions, 24 deletions
diff --git a/fs/char_dev.c b/fs/char_dev.c
index 67b2007f10fe..ea06a3d0364c 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -24,27 +24,6 @@
#include "internal.h"
-/*
- * capabilities for /dev/mem, /dev/kmem and similar directly mappable character
- * devices
- * - permits shared-mmap for read, write and/or exec
- * - does not permit private mmap in NOMMU mode (can't do COW)
- * - no readahead or I/O queue unplugging required
- */
-struct backing_dev_info directly_mappable_cdev_bdi = {
- .name = "char",
- .capabilities = (
-#ifdef CONFIG_MMU
- /* permit private copies of the data to be taken */
- BDI_CAP_MAP_COPY |
-#endif
- /* permit direct mmap, for read, write or exec */
- BDI_CAP_MAP_DIRECT |
- BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP |
- /* no writeback happens */
- BDI_CAP_NO_ACCT_AND_WRITEBACK),
-};
-
static struct kobj_map *cdev_map;
static DEFINE_MUTEX(chrdevs_lock);
@@ -575,8 +554,6 @@ static struct kobject *base_probe(dev_t dev, int *part, void *data)
void __init chrdev_init(void)
{
cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
- if (bdi_init(&directly_mappable_cdev_bdi))
- panic("Failed to init directly mappable cdev bdi");
}
@@ -590,4 +567,3 @@ EXPORT_SYMBOL(cdev_del);
EXPORT_SYMBOL(cdev_add);
EXPORT_SYMBOL(__register_chrdev);
EXPORT_SYMBOL(__unregister_chrdev);
-EXPORT_SYMBOL(directly_mappable_cdev_bdi);