forked from Minki/linux
loop: Add LOOP_CONFIGURE ioctl
This allows userspace to completely setup a loop device with a single
ioctl, removing the in-between state where the device can be partially
configured - eg the loop device has a backing file associated with it,
but is reading from the wrong offset.
Besides removing the intermediate state, another big benefit of this
ioctl is that LOOP_SET_STATUS can be slow; the main reason for this
slowness is that LOOP_SET_STATUS(64) calls blk_mq_freeze_queue() to
freeze the associated queue; this requires waiting for RCU
synchronization, which I've measured can take about 15-20ms on this
device on average.
In addition to doing what LOOP_SET_STATUS can do, LOOP_CONFIGURE can
also be used to:
- Set the correct block size immediately by setting
loop_config.block_size (avoids LOOP_SET_BLOCK_SIZE)
- Explicitly request direct I/O mode by setting LO_FLAGS_DIRECT_IO
in loop_config.info.lo_flags (avoids LOOP_SET_DIRECT_IO)
- Explicitly request read-only mode by setting LO_FLAGS_READ_ONLY
in loop_config.info.lo_flags
Here's setting up ~70 regular loop devices with an offset on an x86
Android device, using LOOP_SET_FD and LOOP_SET_STATUS:
vsoc_x86:/system/apex # time for i in `seq 30 100`;
do losetup -r -o 4096 /dev/block/loop$i com.android.adbd.apex; done
0m03.40s real 0m00.02s user 0m00.03s system
Here's configuring ~70 devices in the same way, but using a modified
losetup that uses the new LOOP_CONFIGURE ioctl:
vsoc_x86:/system/apex # time for i in `seq 30 100`;
do losetup -r -o 4096 /dev/block/loop$i com.android.adbd.apex; done
0m01.94s real 0m00.01s user 0m00.01s system
Signed-off-by: Martijn Coenen <maco@android.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Martijn Coenen
Jens Axboe
parent
faf1d25440
commit
3448914e8c
@ -228,6 +228,19 @@ static void __loop_update_dio(struct loop_device *lo, bool dio)
|
||||
blk_mq_unfreeze_queue(lo->lo_queue);
|
||||
}
|
||||
|
||||
/**
|
||||
* loop_validate_block_size() - validates the passed in block size
|
||||
* @bsize: size to validate
|
||||
*/
|
||||
static int
|
||||
loop_validate_block_size(unsigned short bsize)
|
||||
{
|
||||
if (bsize < 512 || bsize > PAGE_SIZE || !is_power_of_2(bsize))
|
||||
return -EINVAL;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* loop_set_size() - sets device size and notifies userspace
|
||||
* @lo: struct loop_device to set the size for
|
||||
@ -1050,23 +1063,24 @@ loop_set_status_from_info(struct loop_device *lo,
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int loop_set_fd(struct loop_device *lo, fmode_t mode,
|
||||
struct block_device *bdev, unsigned int arg)
|
||||
static int loop_configure(struct loop_device *lo, fmode_t mode,
|
||||
struct block_device *bdev,
|
||||
const struct loop_config *config)
|
||||
{
|
||||
struct file *file;
|
||||
struct inode *inode;
|
||||
struct address_space *mapping;
|
||||
struct block_device *claimed_bdev = NULL;
|
||||
int lo_flags = 0;
|
||||
int error;
|
||||
loff_t size;
|
||||
bool partscan;
|
||||
unsigned short bsize;
|
||||
|
||||
/* This is safe, since we have a reference from open(). */
|
||||
__module_get(THIS_MODULE);
|
||||
|
||||
error = -EBADF;
|
||||
file = fget(arg);
|
||||
file = fget(config->fd);
|
||||
if (!file)
|
||||
goto out;
|
||||
|
||||
@ -1075,7 +1089,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
|
||||
* here to avoid changing device under exclusive owner.
|
||||
*/
|
||||
if (!(mode & FMODE_EXCL)) {
|
||||
claimed_bdev = bd_start_claiming(bdev, loop_set_fd);
|
||||
claimed_bdev = bd_start_claiming(bdev, loop_configure);
|
||||
if (IS_ERR(claimed_bdev)) {
|
||||
error = PTR_ERR(claimed_bdev);
|
||||
goto out_putf;
|
||||
@ -1097,11 +1111,26 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
|
||||
mapping = file->f_mapping;
|
||||
inode = mapping->host;
|
||||
|
||||
size = get_loop_size(lo, file);
|
||||
|
||||
if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) {
|
||||
error = -EINVAL;
|
||||
goto out_unlock;
|
||||
}
|
||||
|
||||
if (config->block_size) {
|
||||
error = loop_validate_block_size(config->block_size);
|
||||
if (error)
|
||||
goto out_unlock;
|
||||
}
|
||||
|
||||
error = loop_set_status_from_info(lo, &config->info);
|
||||
if (error)
|
||||
goto out_unlock;
|
||||
|
||||
if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
|
||||
!file->f_op->write_iter)
|
||||
lo_flags |= LO_FLAGS_READ_ONLY;
|
||||
|
||||
size = get_loop_size(lo, file);
|
||||
lo->lo_flags |= LO_FLAGS_READ_ONLY;
|
||||
|
||||
error = loop_prepare_queue(lo);
|
||||
if (error)
|
||||
@ -1109,30 +1138,28 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
|
||||
|
||||
error = 0;
|
||||
|
||||
set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
|
||||
set_device_ro(bdev, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);
|
||||
|
||||
lo->use_dio = false;
|
||||
lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO;
|
||||
lo->lo_device = bdev;
|
||||
lo->lo_flags = lo_flags;
|
||||
lo->lo_backing_file = file;
|
||||
lo->transfer = NULL;
|
||||
lo->ioctl = NULL;
|
||||
lo->lo_sizelimit = 0;
|
||||
lo->old_gfp_mask = mapping_gfp_mask(mapping);
|
||||
mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
|
||||
|
||||
if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
|
||||
if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
|
||||
blk_queue_write_cache(lo->lo_queue, true, false);
|
||||
|
||||
if (io_is_direct(lo->lo_backing_file) && inode->i_sb->s_bdev) {
|
||||
if (config->block_size)
|
||||
bsize = config->block_size;
|
||||
else if (io_is_direct(lo->lo_backing_file) && inode->i_sb->s_bdev)
|
||||
/* In case of direct I/O, match underlying block size */
|
||||
unsigned short bsize = bdev_logical_block_size(
|
||||
inode->i_sb->s_bdev);
|
||||
bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
|
||||
else
|
||||
bsize = 512;
|
||||
|
||||
blk_queue_logical_block_size(lo->lo_queue, bsize);
|
||||
blk_queue_physical_block_size(lo->lo_queue, bsize);
|
||||
blk_queue_io_min(lo->lo_queue, bsize);
|
||||
}
|
||||
blk_queue_logical_block_size(lo->lo_queue, bsize);
|
||||
blk_queue_physical_block_size(lo->lo_queue, bsize);
|
||||
blk_queue_io_min(lo->lo_queue, bsize);
|
||||
|
||||
loop_update_rotational(lo);
|
||||
loop_update_dio(lo);
|
||||
@ -1155,14 +1182,14 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
|
||||
if (partscan)
|
||||
loop_reread_partitions(lo, bdev);
|
||||
if (claimed_bdev)
|
||||
bd_abort_claiming(bdev, claimed_bdev, loop_set_fd);
|
||||
bd_abort_claiming(bdev, claimed_bdev, loop_configure);
|
||||
return 0;
|
||||
|
||||
out_unlock:
|
||||
mutex_unlock(&loop_ctl_mutex);
|
||||
out_bdev:
|
||||
if (claimed_bdev)
|
||||
bd_abort_claiming(bdev, claimed_bdev, loop_set_fd);
|
||||
bd_abort_claiming(bdev, claimed_bdev, loop_configure);
|
||||
out_putf:
|
||||
fput(file);
|
||||
out:
|
||||
@ -1582,8 +1609,9 @@ static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
|
||||
if (lo->lo_state != Lo_bound)
|
||||
return -ENXIO;
|
||||
|
||||
if (arg < 512 || arg > PAGE_SIZE || !is_power_of_2(arg))
|
||||
return -EINVAL;
|
||||
err = loop_validate_block_size(arg);
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
if (lo->lo_queue->limits.logical_block_size == arg)
|
||||
return 0;
|
||||
@ -1645,8 +1673,27 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode,
|
||||
int err;
|
||||
|
||||
switch (cmd) {
|
||||
case LOOP_SET_FD:
|
||||
return loop_set_fd(lo, mode, bdev, arg);
|
||||
case LOOP_SET_FD: {
|
||||
/*
|
||||
* Legacy case - pass in a zeroed out struct loop_config with
|
||||
* only the file descriptor set , which corresponds with the
|
||||
* default parameters we'd have used otherwise.
|
||||
*/
|
||||
struct loop_config config;
|
||||
|
||||
memset(&config, 0, sizeof(config));
|
||||
config.fd = arg;
|
||||
|
||||
return loop_configure(lo, mode, bdev, &config);
|
||||
}
|
||||
case LOOP_CONFIGURE: {
|
||||
struct loop_config config;
|
||||
|
||||
if (copy_from_user(&config, argp, sizeof(config)))
|
||||
return -EFAULT;
|
||||
|
||||
return loop_configure(lo, mode, bdev, &config);
|
||||
}
|
||||
case LOOP_CHANGE_FD:
|
||||
return loop_change_fd(lo, bdev, arg);
|
||||
case LOOP_CLR_FD:
|
||||
@ -1818,6 +1865,7 @@ static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
|
||||
case LOOP_CLR_FD:
|
||||
case LOOP_GET_STATUS64:
|
||||
case LOOP_SET_STATUS64:
|
||||
case LOOP_CONFIGURE:
|
||||
arg = (unsigned long) compat_ptr(arg);
|
||||
/* fall through */
|
||||
case LOOP_SET_FD:
|
||||
|
||||
@ -31,6 +31,10 @@ enum {
|
||||
/* LO_FLAGS that can be cleared using LOOP_SET_STATUS(64) */
|
||||
#define LOOP_SET_STATUS_CLEARABLE_FLAGS (LO_FLAGS_AUTOCLEAR)
|
||||
|
||||
/* LO_FLAGS that can be set using LOOP_CONFIGURE */
|
||||
#define LOOP_CONFIGURE_SETTABLE_FLAGS (LO_FLAGS_READ_ONLY | LO_FLAGS_AUTOCLEAR \
|
||||
| LO_FLAGS_PARTSCAN | LO_FLAGS_DIRECT_IO)
|
||||
|
||||
#include <asm/posix_types.h> /* for __kernel_old_dev_t */
|
||||
#include <linux/types.h> /* for __u64 */
|
||||
|
||||
@ -66,6 +70,22 @@ struct loop_info64 {
|
||||
__u64 lo_init[2];
|
||||
};
|
||||
|
||||
/**
|
||||
* struct loop_config - Complete configuration for a loop device.
|
||||
* @fd: fd of the file to be used as a backing file for the loop device.
|
||||
* @block_size: block size to use; ignored if 0.
|
||||
* @info: struct loop_info64 to configure the loop device with.
|
||||
*
|
||||
* This structure is used with the LOOP_CONFIGURE ioctl, and can be used to
|
||||
* atomically setup and configure all loop device parameters at once.
|
||||
*/
|
||||
struct loop_config {
|
||||
__u32 fd;
|
||||
__u32 block_size;
|
||||
struct loop_info64 info;
|
||||
__u64 __reserved[8];
|
||||
};
|
||||
|
||||
/*
|
||||
* Loop filter types
|
||||
*/
|
||||
@ -96,6 +116,7 @@ struct loop_info64 {
|
||||
#define LOOP_SET_CAPACITY 0x4C07
|
||||
#define LOOP_SET_DIRECT_IO 0x4C08
|
||||
#define LOOP_SET_BLOCK_SIZE 0x4C09
|
||||
#define LOOP_CONFIGURE 0x4C0A
|
||||
|
||||
/* /dev/loop-control interface */
|
||||
#define LOOP_CTL_ADD 0x4C80
|
||||
|
||||
Loading…
Reference in New Issue
Block a user