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loop: Clean up LOOP_SET_STATUS lo_flags handling

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LOOP_SET_STATUS(64) will actually allow some lo_flags to be modified; in
particular, LO_FLAGS_AUTOCLEAR can be set and cleared, whereas
LO_FLAGS_PARTSCAN can be set to request a partition scan. Make this
explicit by updating the UAPI to include the flags that can be
set/cleared using this ioctl.

The implementation can then blindly take over the passed in flags,
and use the previous flags for those flags that can't be set / cleared
using LOOP_SET_STATUS.

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 2020-05-13 15:38:44 +02:00 committed by Jens Axboe
parent 571fae6e29
commit faf1d25440
2 changed files with 21 additions and 8 deletions
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19
drivers/block/loop.c
View File

@ -1036,9 +1036,7 @@ loop_set_status_from_info(struct loop_device *lo,
lo->transfer = xfer->transfer;
lo->ioctl = xfer->ioctl;
if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
(info->lo_flags & LO_FLAGS_AUTOCLEAR))
lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
lo->lo_flags = info->lo_flags;
lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
lo->lo_init[0] = info->lo_init[0];
@ -1323,6 +1321,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
int err;
struct block_device *bdev;
kuid_t uid = current_uid();
int prev_lo_flags;
bool partscan = false;
bool size_changed = false;
@ -1359,10 +1358,19 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
goto out_unfreeze;
}
prev_lo_flags = lo->lo_flags;
err = loop_set_status_from_info(lo, info);
if (err)
goto out_unfreeze;
/* Mask out flags that can't be set using LOOP_SET_STATUS. */
lo->lo_flags &= ~LOOP_SET_STATUS_SETTABLE_FLAGS;
/* For those flags, use the previous values instead */
lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS;
/* For flags that can't be cleared, use previous values too */
lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS;
if (size_changed) {
loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
lo->lo_backing_file);
@ -1377,9 +1385,8 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
out_unfreeze:
blk_mq_unfreeze_queue(lo->lo_queue);
if (!err && (info->lo_flags & LO_FLAGS_PARTSCAN) &&
!(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
lo->lo_flags |= LO_FLAGS_PARTSCAN;
if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) &&
!(prev_lo_flags & LO_FLAGS_PARTSCAN)) {
lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
bdev = lo->lo_device;
partscan = true;

10
include/uapi/linux/loop.h
View File

@ -25,6 +25,12 @@ enum {
LO_FLAGS_DIRECT_IO = 16,
};
/* LO_FLAGS that can be set using LOOP_SET_STATUS(64) */
#define LOOP_SET_STATUS_SETTABLE_FLAGS (LO_FLAGS_AUTOCLEAR | LO_FLAGS_PARTSCAN)
/* LO_FLAGS that can be cleared using LOOP_SET_STATUS(64) */
#define LOOP_SET_STATUS_CLEARABLE_FLAGS (LO_FLAGS_AUTOCLEAR)
#include <asm/posix_types.h> /* for __kernel_old_dev_t */
#include <linux/types.h> /* for __u64 */
@ -37,7 +43,7 @@ struct loop_info {
int lo_offset;
int lo_encrypt_type;
int lo_encrypt_key_size; /* ioctl w/o */
int lo_flags; /* ioctl r/o */
int lo_flags;
char lo_name[LO_NAME_SIZE];
unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
unsigned long lo_init[2];
@ -53,7 +59,7 @@ struct loop_info64 {
__u32 lo_number; /* ioctl r/o */
__u32 lo_encrypt_type;
__u32 lo_encrypt_key_size; /* ioctl w/o */
__u32 lo_flags; /* ioctl r/o */
__u32 lo_flags;
__u8 lo_file_name[LO_NAME_SIZE];
__u8 lo_crypt_name[LO_NAME_SIZE];
__u8 lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */