btrfs: add readonly flag

setting the readonly flag prevents writes in case an error is detected

Signed-off-by: Arne Jansen <sensille@gmx.net>

4 files changed, 16 insertions, 12 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index b7373b14e4cd..ee904666b766 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2657,7 +2657,7 @@ void btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
 
 /* scrub.c */
 int btrfs_scrub_dev(struct btrfs_root *root, u64 devid, u64 start, u64 end,
-                    struct btrfs_scrub_progress *progress);
+                    struct btrfs_scrub_progress *progress, int readonly);
 int btrfs_scrub_pause(struct btrfs_root *root);
 int btrfs_scrub_pause_super(struct btrfs_root *root);
 int btrfs_scrub_continue(struct btrfs_root *root);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 205cd011d2f3..f0a74f014748 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2547,7 +2547,7 @@ static long btrfs_ioctl_scrub(struct btrfs_root *root, void __user *arg)
                 return PTR_ERR(sa);
 
         ret = btrfs_scrub_dev(root, sa->devid, sa->start, sa->end,
-                              &sa->progress);
+                              &sa->progress, sa->flags & BTRFS_SCRUB_READONLY);
 
         if (copy_to_user(arg, sa, sizeof(*sa)))
                 ret = -EFAULT;
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 1a638ceeead8..e5e0ee2cad4e 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -81,6 +81,7 @@ struct btrfs_scrub_progress {
                                          * Intermittent error. */
 };
 
+#define BTRFS_SCRUB_READONLY    1
 struct btrfs_ioctl_scrub_args {
         __u64 devid;                            /* in */
         __u64 start;                            /* in */
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 6a50801ecfa0..a31f2a9bd2e2 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -42,7 +42,6 @@
  *  - In case of a read error on files with nodatasum, map the file and read
  *    the extent to trigger a writeback of the good copy
  *  - track and record media errors, throw out bad devices
- *  - add a readonly mode
  *  - add a mode to also read unallocated space
  *  - make the prefetch cancellable
  */
@@ -99,6 +98,7 @@ struct scrub_dev {
         u16                     csum_size;
         struct list_head        csum_list;
         atomic_t                cancel_req;
+        int                     readonly;
         /*
          * statistics
          */
@@ -329,14 +329,16 @@ static void scrub_fixup(struct scrub_bio *sbio, int ix)
         if (i == multi->num_stripes)
                 goto uncorrectable;
 
-        /*
-         * bi_io_vec[ix].bv_page now contains good data, write it back
-         */
-        if (scrub_fixup_io(WRITE, sdev->dev->bdev,
-                           (sbio->physical + ix * PAGE_SIZE) >> 9,
-                           sbio->bio->bi_io_vec[ix].bv_page)) {
-                /* I/O-error, writeback failed, give up */
-                goto uncorrectable;
+        if (!sdev->readonly) {
+                /*
+                 * bi_io_vec[ix].bv_page now contains good data, write it back
+                 */
+                if (scrub_fixup_io(WRITE, sdev->dev->bdev,
+                                   (sbio->physical + ix * PAGE_SIZE) >> 9,
+                                   sbio->bio->bi_io_vec[ix].bv_page)) {
+                        /* I/O-error, writeback failed, give up */
+                        goto uncorrectable;
+                }
         }
 
         kfree(multi);
@@ -1156,7 +1158,7 @@ static noinline_for_stack void scrub_workers_put(struct btrfs_root *root)
 
 
 int btrfs_scrub_dev(struct btrfs_root *root, u64 devid, u64 start, u64 end,
-                    struct btrfs_scrub_progress *progress)
+                    struct btrfs_scrub_progress *progress, int readonly)
 {
         struct scrub_dev *sdev;
         struct btrfs_fs_info *fs_info = root->fs_info;
@@ -1209,6 +1211,7 @@ int btrfs_scrub_dev(struct btrfs_root *root, u64 devid, u64 start, u64 end,
                 scrub_workers_put(root);
                 return PTR_ERR(sdev);
         }
+        sdev->readonly = readonly;
         dev->scrub_device = sdev;
 
         atomic_inc(&fs_info->scrubs_running);