[Qemu-devel] [PATCH 1/3] qemu-img check -r for repairing images

[Kevin Wolf <kwolf@redhat.com>]

The QED block driver already provides the functionality to not only
detect inconsistencies in images, but also fix them. However, this
functionality cannot be manually invoked with qemu-img, but the
check happens only automatically during bdrv_open().

This adds a -r switch to qemu-img check that allows manual invocation
of an image repair.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c          |    4 ++--
 block.h          |    7 ++++++-
 block/qcow2.c    |    7 ++++++-
 block/qed.c      |    5 +++--
 block/vdi.c      |    7 ++++++-
 block_int.h      |    3 ++-
 qemu-img-cmds.hx |    4 ++--
 qemu-img.c       |   25 ++++++++++++++++++++++---
 qemu-img.texi    |    7 ++++++-
 9 files changed, 55 insertions(+), 14 deletions(-)

diff --git a/block.c b/block.c
index acebe46..8e928b9 100644
--- a/block.c
+++ b/block.c
@@ -1211,14 +1211,14 @@ bool bdrv_dev_is_medium_locked(BlockDriverState *bs)
  * free of errors) or -errno when an internal error occurred. The results of the
  * check are stored in res.
  */
-int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res)
+int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix)
 {
     if (bs->drv->bdrv_check == NULL) {
         return -ENOTSUP;
     }
 
     memset(res, 0, sizeof(*res));
-    return bs->drv->bdrv_check(bs, res);
+    return bs->drv->bdrv_check(bs, res, fix);
 }
 
 #define COMMIT_BUF_SECTORS 2048
diff --git a/block.h b/block.h
index 799cf48..61b7e8e 100644
--- a/block.h
+++ b/block.h
@@ -190,7 +190,12 @@ typedef struct BdrvCheckResult {
     BlockFragInfo bfi;
 } BdrvCheckResult;
 
-int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res);
+typedef enum {
+    BDRV_FIX_LEAKS    = 1,
+    BDRV_FIX_ERRORS   = 2,
+} BdrvCheckMode;
+
+int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix);
 
 /* async block I/O */
 typedef void BlockDriverDirtyHandler(BlockDriverState *bs, int64_t sector,
diff --git a/block/qcow2.c b/block/qcow2.c
index 3997e19..23cc920 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1508,8 +1508,13 @@ static int qcow2_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 }
 
 
-static int qcow2_check(BlockDriverState *bs, BdrvCheckResult *result)
+static int qcow2_check(BlockDriverState *bs, BdrvCheckResult *result,
+                       BdrvCheckMode fix)
 {
+    if (fix) {
+        return -ENOTSUP;
+    }
+
     return qcow2_check_refcounts(bs, result);
 }
 
diff --git a/block/qed.c b/block/qed.c
index 30a31f9..ab59724 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -1517,11 +1517,12 @@ static void bdrv_qed_invalidate_cache(BlockDriverState *bs)
     bdrv_qed_open(bs, bs->open_flags);
 }
 
-static int bdrv_qed_check(BlockDriverState *bs, BdrvCheckResult *result)
+static int bdrv_qed_check(BlockDriverState *bs, BdrvCheckResult *result,
+                          BdrvCheckMode fix)
 {
     BDRVQEDState *s = bs->opaque;
 
-    return qed_check(s, result, false);
+    return qed_check(s, result, !!fix);
 }
 
 static QEMUOptionParameter qed_create_options[] = {
diff --git a/block/vdi.c b/block/vdi.c
index 119d3c7..57325d6 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -277,7 +277,8 @@ static void vdi_header_print(VdiHeader *header)
 }
 #endif
 
-static int vdi_check(BlockDriverState *bs, BdrvCheckResult *res)
+static int vdi_check(BlockDriverState *bs, BdrvCheckResult *res,
+                     BdrvCheckMode fix)
 {
     /* TODO: additional checks possible. */
     BDRVVdiState *s = (BDRVVdiState *)bs->opaque;
@@ -286,6 +287,10 @@ static int vdi_check(BlockDriverState *bs, BdrvCheckResult *res)
     uint32_t *bmap;
     logout("\n");
 
+    if (fix) {
+        return -ENOTSUP;
+    }
+
     bmap = g_malloc(s->header.blocks_in_image * sizeof(uint32_t));
     memset(bmap, 0xff, s->header.blocks_in_image * sizeof(uint32_t));
 
diff --git a/block_int.h b/block_int.h
index b80e66d..a0fffe1 100644
--- a/block_int.h
+++ b/block_int.h
@@ -241,7 +241,8 @@ struct BlockDriver {
      * Returns 0 for completed check, -errno for internal errors.
      * The check results are stored in result.
      */
-    int (*bdrv_check)(BlockDriverState* bs, BdrvCheckResult *result);
+    int (*bdrv_check)(BlockDriverState* bs, BdrvCheckResult *result,
+        BdrvCheckMode fix);
 
     void (*bdrv_debug_event)(BlockDriverState *bs, BlkDebugEvent event);
 
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index 49dce7c..39419a0 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -10,9 +10,9 @@ STEXI
 ETEXI
 
 DEF("check", img_check,
-    "check [-f fmt] filename")
+    "check [-f fmt] [-r [leaks | all]] filename")
 STEXI
-@item check [-f @var{fmt}] @var{filename}
+@item check [-f @var{fmt}] [-r [leaks | all]] @var{filename}
 ETEXI
 
 DEF("create", img_create,
diff --git a/qemu-img.c b/qemu-img.c
index 5434ddc..b151076 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -85,6 +85,12 @@ static void help(void)
            "  '-S' indicates the consecutive number of bytes that must contain only zeros\n"
            "       for qemu-img to create a sparse image during conversion\n"
            "\n"
+           "Parameters to check subcommand:\n"
+           "  '-r' tries to repair any inconsistencies that are found during the check.\n"
+           "       '-r leaks' repairs only cluster leaks, whereas '-r all' fixes all\n"
+           "       kinds of errors, with a higher risk of choosing the wrong fix or\n"
+           "       hiding corruption that has already occured.\n"
+           "\n"
            "Parameters to snapshot subcommand:\n"
            "  'snapshot' is the name of the snapshot to create, apply or delete\n"
            "  '-a' applies a snapshot (revert disk to saved state)\n"
@@ -372,10 +378,12 @@ static int img_check(int argc, char **argv)
     const char *filename, *fmt;
     BlockDriverState *bs;
     BdrvCheckResult result;
+    int fix = 0;
+    int flags = BDRV_O_FLAGS;
 
     fmt = NULL;
     for(;;) {
-        c = getopt(argc, argv, "f:h");
+        c = getopt(argc, argv, "f:hr:");
         if (c == -1) {
             break;
         }
@@ -387,6 +395,17 @@ static int img_check(int argc, char **argv)
         case 'f':
             fmt = optarg;
             break;
+        case 'r':
+            flags |= BDRV_O_RDWR;
+
+            if (!strcmp(optarg, "leaks")) {
+                fix = BDRV_FIX_LEAKS;
+            } else if (!strcmp(optarg, "all")) {
+                fix = BDRV_FIX_LEAKS | BDRV_FIX_ERRORS;
+            } else {
+                help();
+            }
+            break;
         }
     }
     if (optind >= argc) {
@@ -394,11 +413,11 @@ static int img_check(int argc, char **argv)
     }
     filename = argv[optind++];
 
-    bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS);
+    bs = bdrv_new_open(filename, fmt, flags);
     if (!bs) {
         return 1;
     }
-    ret = bdrv_check(bs, &result);
+    ret = bdrv_check(bs, &result, fix);
 
     if (ret == -ENOTSUP) {
         error_report("This image format does not support checks");
diff --git a/qemu-img.texi b/qemu-img.texi
index 5a3dc41..34610a3 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -70,10 +70,15 @@ lists all snapshots in the given image
 Command description:
 
 @table @option
-@item check [-f @var{fmt}] @var{filename}
+@item check [-f @var{fmt}] [-r [leaks | all]] @var{filename}
 
 Perform a consistency check on the disk image @var{filename}.
 
+If @code{-r} is specified, qemu-img tries to repair any inconsistencies found
+during the check. @code{-r leaks} repairs only cluster leaks, whereas
+@code{-r all} fixes all kinds of errors, with a higher risk of choosing the
+wrong fix or hiding corruption that has already occured.
+
 Only the formats @code{qcow2}, @code{qed} and @code{vdi} support
 consistency checks.
 
-- 
1.7.6.5