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Commit e515bc15 authored by Martijn Coenen's avatar Martijn Coenen
Browse files

BACKPORT: loop: Clean up LOOP_SET_STATUS lo_flags handling 



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: default avatarMartijn Coenen <maco@android.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Bug: 148607611
(cherry picked from commit faf1d25440d6ad06d509dada4b6fe62fea844370)
Change-Id: I88487db28e785ee83e400904b685ef9e98c0287d
parent 77a5e7c3

drivers/block/loop.c

+12 −6
Original line number Diff line number Diff line
@@ -970,9 +970,7 @@ 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];
@@ -1168,6 +1166,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) 
{

	int err;

	kuid_t uid = current_uid();

	int prev_lo_flags;

	bool size_changed = false;



	if (lo->lo_encrypt_key_size &&
@@ -1197,10 +1196,18 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) 
		goto exit;

	}



	prev_lo_flags = lo->lo_flags;



	err = loop_set_status_from_info(lo, info);

	if (err)

		goto exit;



	/* 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);
@@ -1215,9 +1222,8 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) 
 exit:

	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;

		loop_reread_partitions(lo, lo->lo_device);

	}

include/uapi/linux/loop.h

+8 −2
Original line number Diff line number Diff line
@@ -24,6 +24,12 @@ 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 */
@@ -36,7 +42,7 @@ 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];
@@ -52,7 +58,7 @@ 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 */