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path: root/drivers/block/loop.c
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Diffstat (limited to 'drivers/block/loop.c')
-rw-r--r--drivers/block/loop.c111
1 files changed, 104 insertions, 7 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index c77983e..3d80682 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -76,6 +76,8 @@
#include <linux/splice.h>
#include <linux/sysfs.h>
#include <linux/miscdevice.h>
+#include <linux/falloc.h>
+
#include <asm/uaccess.h>
static DEFINE_IDR(loop_index_idr);
@@ -407,6 +409,29 @@ static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
}
}
+ /*
+ * We use punch hole to reclaim the free space used by the
+ * image a.k.a. discard. However we do support discard if
+ * encryption is enabled, because it may give an attacker
+ * useful information.
+ */
+ if (bio->bi_rw & REQ_DISCARD) {
+ struct file *file = lo->lo_backing_file;
+ int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
+
+ if ((!file->f_op->fallocate) ||
+ lo->lo_encrypt_key_size) {
+ ret = -EOPNOTSUPP;
+ goto out;
+ }
+ ret = file->f_op->fallocate(file, mode, pos,
+ bio->bi_size);
+ if (unlikely(ret && ret != -EINVAL &&
+ ret != -EOPNOTSUPP))
+ ret = -EIO;
+ goto out;
+ }
+
ret = lo_send(lo, bio, pos);
if ((bio->bi_rw & REQ_FUA) && !ret) {
@@ -622,7 +647,7 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
goto out_putf;
fput(old_file);
- if (max_part > 0)
+ if (lo->lo_flags & LO_FLAGS_PARTSCAN)
ioctl_by_bdev(bdev, BLKRRPART, 0);
return 0;
@@ -699,16 +724,25 @@ static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
return sprintf(buf, "%s\n", autoclear ? "1" : "0");
}
+static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
+{
+ int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
+
+ return sprintf(buf, "%s\n", partscan ? "1" : "0");
+}
+
LOOP_ATTR_RO(backing_file);
LOOP_ATTR_RO(offset);
LOOP_ATTR_RO(sizelimit);
LOOP_ATTR_RO(autoclear);
+LOOP_ATTR_RO(partscan);
static struct attribute *loop_attrs[] = {
&loop_attr_backing_file.attr,
&loop_attr_offset.attr,
&loop_attr_sizelimit.attr,
&loop_attr_autoclear.attr,
+ &loop_attr_partscan.attr,
NULL,
};
@@ -729,6 +763,35 @@ static void loop_sysfs_exit(struct loop_device *lo)
&loop_attribute_group);
}
+static void loop_config_discard(struct loop_device *lo)
+{
+ struct file *file = lo->lo_backing_file;
+ struct inode *inode = file->f_mapping->host;
+ struct request_queue *q = lo->lo_queue;
+
+ /*
+ * We use punch hole to reclaim the free space used by the
+ * image a.k.a. discard. However we do support discard if
+ * encryption is enabled, because it may give an attacker
+ * useful information.
+ */
+ if ((!file->f_op->fallocate) ||
+ lo->lo_encrypt_key_size) {
+ q->limits.discard_granularity = 0;
+ q->limits.discard_alignment = 0;
+ q->limits.max_discard_sectors = 0;
+ q->limits.discard_zeroes_data = 0;
+ queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
+ return;
+ }
+
+ q->limits.discard_granularity = inode->i_sb->s_blocksize;
+ q->limits.discard_alignment = inode->i_sb->s_blocksize;
+ q->limits.max_discard_sectors = UINT_MAX >> 9;
+ q->limits.discard_zeroes_data = 1;
+ queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
+}
+
static int loop_set_fd(struct loop_device *lo, fmode_t mode,
struct block_device *bdev, unsigned int arg)
{
@@ -829,7 +892,9 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
}
lo->lo_state = Lo_bound;
wake_up_process(lo->lo_thread);
- if (max_part > 0)
+ if (part_shift)
+ lo->lo_flags |= LO_FLAGS_PARTSCAN;
+ if (lo->lo_flags & LO_FLAGS_PARTSCAN)
ioctl_by_bdev(bdev, BLKRRPART, 0);
return 0;
@@ -890,10 +955,11 @@ loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
return err;
}
-static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
+static int loop_clr_fd(struct loop_device *lo)
{
struct file *filp = lo->lo_backing_file;
gfp_t gfp = lo->old_gfp_mask;
+ struct block_device *bdev = lo->lo_device;
if (lo->lo_state != Lo_bound)
return -ENXIO;
@@ -922,7 +988,6 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
lo->lo_offset = 0;
lo->lo_sizelimit = 0;
lo->lo_encrypt_key_size = 0;
- lo->lo_flags = 0;
lo->lo_thread = NULL;
memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
@@ -940,8 +1005,11 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
lo->lo_state = Lo_unbound;
/* This is safe: open() is still holding a reference. */
module_put(THIS_MODULE);
- if (max_part > 0 && bdev)
+ if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
ioctl_by_bdev(bdev, BLKRRPART, 0);
+ lo->lo_flags = 0;
+ if (!part_shift)
+ lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
mutex_unlock(&lo->lo_ctl_mutex);
/*
* Need not hold lo_ctl_mutex to fput backing file.
@@ -995,6 +1063,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
if (figure_loop_size(lo))
return -EFBIG;
}
+ loop_config_discard(lo);
memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
@@ -1010,6 +1079,13 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
(info->lo_flags & LO_FLAGS_AUTOCLEAR))
lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
+ if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
+ !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
+ lo->lo_flags |= LO_FLAGS_PARTSCAN;
+ lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
+ ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
+ }
+
lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
lo->lo_init[0] = info->lo_init[0];
lo->lo_init[1] = info->lo_init[1];
@@ -1203,7 +1279,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode,
break;
case LOOP_CLR_FD:
/* loop_clr_fd would have unlocked lo_ctl_mutex on success */
- err = loop_clr_fd(lo, bdev);
+ err = loop_clr_fd(lo);
if (!err)
goto out_unlocked;
break;
@@ -1423,7 +1499,7 @@ static int lo_release(struct gendisk *disk, fmode_t mode)
* In autoclear mode, stop the loop thread
* and remove configuration after last close.
*/
- err = loop_clr_fd(lo, NULL);
+ err = loop_clr_fd(lo);
if (!err)
goto out_unlocked;
} else {
@@ -1545,6 +1621,27 @@ static int loop_add(struct loop_device **l, int i)
if (!disk)
goto out_free_queue;
+ /*
+ * Disable partition scanning by default. The in-kernel partition
+ * scanning can be requested individually per-device during its
+ * setup. Userspace can always add and remove partitions from all
+ * devices. The needed partition minors are allocated from the
+ * extended minor space, the main loop device numbers will continue
+ * to match the loop minors, regardless of the number of partitions
+ * used.
+ *
+ * If max_part is given, partition scanning is globally enabled for
+ * all loop devices. The minors for the main loop devices will be
+ * multiples of max_part.
+ *
+ * Note: Global-for-all-devices, set-only-at-init, read-only module
+ * parameteters like 'max_loop' and 'max_part' make things needlessly
+ * complicated, are too static, inflexible and may surprise
+ * userspace tools. Parameters like this in general should be avoided.
+ */
+ if (!part_shift)
+ disk->flags |= GENHD_FL_NO_PART_SCAN;
+ disk->flags |= GENHD_FL_EXT_DEVT;
mutex_init(&lo->lo_ctl_mutex);
lo->lo_number = i;
lo->lo_thread = NULL;
generated by cgit v1.1 at 2024-12-27 08:12:02 +0000