1 files changed, 129 insertions, 122 deletions

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 4720c7ade0ae..3d806820280e 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);
@@ -203,74 +205,6 @@ lo_do_transfer(struct loop_device *lo, int cmd,
 }
 
 /**
- * do_lo_send_aops - helper for writing data to a loop device
- *
- * This is the fast version for backing filesystems which implement the address
- * space operations write_begin and write_end.
- */
-static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
-                loff_t pos, struct page *unused)
-{
-        struct file *file = lo->lo_backing_file; /* kudos to NFsckingS */
-        struct address_space *mapping = file->f_mapping;
-        pgoff_t index;
-        unsigned offset, bv_offs;
-        int len, ret;
-
-        mutex_lock(&mapping->host->i_mutex);
-        index = pos >> PAGE_CACHE_SHIFT;
-        offset = pos & ((pgoff_t)PAGE_CACHE_SIZE - 1);
-        bv_offs = bvec->bv_offset;
-        len = bvec->bv_len;
-        while (len > 0) {
-                sector_t IV;
-                unsigned size, copied;
-                int transfer_result;
-                struct page *page;
-                void *fsdata;
-
-                IV = ((sector_t)index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9);
-                size = PAGE_CACHE_SIZE - offset;
-                if (size > len)
-                        size = len;
-
-                ret = pagecache_write_begin(file, mapping, pos, size, 0,
-                                                        &page, &fsdata);
-                if (ret)
-                        goto fail;
-
-                file_update_time(file);
-
-                transfer_result = lo_do_transfer(lo, WRITE, page, offset,
-                                bvec->bv_page, bv_offs, size, IV);
-                copied = size;
-                if (unlikely(transfer_result))
-                        copied = 0;
-
-                ret = pagecache_write_end(file, mapping, pos, size, copied,
-                                                        page, fsdata);
-                if (ret < 0 || ret != copied)
-                        goto fail;
-
-                if (unlikely(transfer_result))
-                        goto fail;
-
-                bv_offs += copied;
-                len -= copied;
-                offset = 0;
-                index++;
-                pos += copied;
-        }
-        ret = 0;
-out:
-        mutex_unlock(&mapping->host->i_mutex);
-        return ret;
-fail:
-        ret = -1;
-        goto out;
-}
-
-/**
  * __do_lo_send_write - helper for writing data to a loop device
  *
  * This helper just factors out common code between do_lo_send_direct_write()
@@ -297,10 +231,8 @@ static int __do_lo_send_write(struct file *file,
 /**
  * do_lo_send_direct_write - helper for writing data to a loop device
  *
- * This is the fast, non-transforming version for backing filesystems which do
- * not implement the address space operations write_begin and write_end.
- * It uses the write file operation which should be present on all writeable
- * filesystems.
+ * This is the fast, non-transforming version that does not need double
+ * buffering.
  */
 static int do_lo_send_direct_write(struct loop_device *lo,
                 struct bio_vec *bvec, loff_t pos, struct page *page)
@@ -316,15 +248,9 @@ static int do_lo_send_direct_write(struct loop_device *lo,
 /**
  * do_lo_send_write - helper for writing data to a loop device
  *
- * This is the slow, transforming version for filesystems which do not
- * implement the address space operations write_begin and write_end.  It
- * uses the write file operation which should be present on all writeable
- * filesystems.
- *
- * Using fops->write is slower than using aops->{prepare,commit}_write in the
- * transforming case because we need to double buffer the data as we cannot do
- * the transformations in place as we do not have direct access to the
- * destination pages of the backing file.
+ * This is the slow, transforming version that needs to double buffer the
+ * data as it cannot do the transformations in place without having direct
+ * access to the destination pages of the backing file.
  */
 static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
                 loff_t pos, struct page *page)
@@ -350,17 +276,16 @@ static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
         struct page *page = NULL;
         int i, ret = 0;
 
-        do_lo_send = do_lo_send_aops;
-        if (!(lo->lo_flags & LO_FLAGS_USE_AOPS)) {
+        if (lo->transfer != transfer_none) {
+                page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
+                if (unlikely(!page))
+                        goto fail;
+                kmap(page);
+                do_lo_send = do_lo_send_write;
+        } else {
                 do_lo_send = do_lo_send_direct_write;
-                if (lo->transfer != transfer_none) {
-                        page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
-                        if (unlikely(!page))
-                                goto fail;
-                        kmap(page);
-                        do_lo_send = do_lo_send_write;
-                }
         }
+
         bio_for_each_segment(bvec, bio, i) {
                 ret = do_lo_send(lo, bvec, pos, page);
                 if (ret < 0)
@@ -484,6 +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) {
@@ -514,7 +462,7 @@ static struct bio *loop_get_bio(struct loop_device *lo)
         return bio_list_pop(&lo->lo_bio_list);
 }
 
-static int loop_make_request(struct request_queue *q, struct bio *old_bio)
+static void loop_make_request(struct request_queue *q, struct bio *old_bio)
 {
         struct loop_device *lo = q->queuedata;
         int rw = bio_rw(old_bio);
@@ -532,12 +480,11 @@ static int loop_make_request(struct request_queue *q, struct bio *old_bio)
         loop_add_bio(lo, old_bio);
         wake_up(&lo->lo_event);
         spin_unlock_irq(&lo->lo_lock);
-        return 0;
+        return;
 
 out:
         spin_unlock_irq(&lo->lo_lock);
         bio_io_error(old_bio);
-        return 0;
 }
 
 struct switch_request {
@@ -700,7 +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;
 
@@ -777,16 +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,
 };
 
@@ -807,6 +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)
 {
@@ -849,35 +834,23 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
         mapping = file->f_mapping;
         inode = mapping->host;
 
-        if (!(file->f_mode & FMODE_WRITE))
-                lo_flags |= LO_FLAGS_READ_ONLY;
-
         error = -EINVAL;
-        if (S_ISREG(inode->i_mode) || S_ISBLK(inode->i_mode)) {
-                const struct address_space_operations *aops = mapping->a_ops;
-
-                if (aops->write_begin)
-                        lo_flags |= LO_FLAGS_USE_AOPS;
-                if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write)
-                        lo_flags |= LO_FLAGS_READ_ONLY;
+        if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
+                goto out_putf;
 
-                lo_blocksize = S_ISBLK(inode->i_mode) ?
-                        inode->i_bdev->bd_block_size : PAGE_SIZE;
+        if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
+            !file->f_op->write)
+                lo_flags |= LO_FLAGS_READ_ONLY;
 
-                error = 0;
-        } else {
-                goto out_putf;
-        }
+        lo_blocksize = S_ISBLK(inode->i_mode) ?
+                inode->i_bdev->bd_block_size : PAGE_SIZE;
 
+        error = -EFBIG;
         size = get_loop_size(lo, file);
-
-        if ((loff_t)(sector_t)size != size) {
-                error = -EFBIG;
+        if ((loff_t)(sector_t)size != size)
                 goto out_putf;
-        }
 
-        if (!(mode & FMODE_WRITE))
-                lo_flags |= LO_FLAGS_READ_ONLY;
+        error = 0;
 
         set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
 
@@ -919,7 +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;
 
@@ -980,10 +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;
@@ -1012,7 +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);
@@ -1030,8 +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.
@@ -1085,6 +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);
@@ -1100,6 +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];
@@ -1293,7 +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;
@@ -1513,7 +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 {
@@ -1635,6 +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;