[Qemu-devel] [PATCH 0/2] raw-posix: Fix raw_co_get_block_status()

[Qemu-devel] [PATCH 0/2] raw-posix: Fix raw_co_get_block_status()

[Max Reitz]

raw_co_get_block_status() should return 0 and set *pnum to 0 after the
EOF; currently it does this merely by accident, so implement it
directly.

While doing that, centralize the generation of
raw_co_get_block_status()'s return value along the way.


Max Reitz (2):
  raw-posix: Fix raw_co_get_block_status() after EOF
  raw-posix: raw_co_get_block_status() return value

 block/raw-posix.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

-- 
2.1.0

[Qemu-devel] [PATCH 1/2] raw-posix: Fix raw_co_get_block_status() after EOF

[Max Reitz]

As its comment states, raw_co_get_block_status() should unconditionally
return 0 and set *pnum to 0 for after EOF.

An assertion after lseek(..., SEEK_HOLE) tried to catch this case by
asserting that errno != -ENXIO (which would indicate a position after
the EOF); but it should be errno != ENXIO instead. Fix this, too.

Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/raw-posix.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/block/raw-posix.c b/block/raw-posix.c
index a253697..de4e3f3 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1509,9 +1509,9 @@ static int64_t try_seek_hole(BlockDriverState *bs, off_t start, off_t *data,
 
     *hole = lseek(s->fd, start, SEEK_HOLE);
     if (*hole == -1) {
-        /* -ENXIO indicates that sector_num was past the end of the file.
+        /* ENXIO indicates that sector_num was past the end of the file.
          * There is a virtual hole there.  */
-        assert(errno != -ENXIO);
+        assert(errno != ENXIO);
 
         return -errno;
     }
@@ -1560,6 +1560,10 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
     }
 
     start = sector_num * BDRV_SECTOR_SIZE;
+    if (start >= bdrv_getlength(bs)) {
+        *pnum = 0;
+        return 0;
+    }
 
     ret = try_fiemap(bs, start, &data, &hole, nb_sectors, pnum);
     if (ret < 0) {
-- 
2.1.0

[Qemu-devel] [PATCH 2/2] raw-posix: raw_co_get_block_status() return value

[Max Reitz]

Instead of generating the full return value thrice in try_fiemap(),
try_seek_hole() and as a fall-back in raw_co_get_block_status() itself,
generate the value only in raw_co_get_block_status().

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/raw-posix.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/block/raw-posix.c b/block/raw-posix.c
index de4e3f3..7e1cc02 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1455,12 +1455,12 @@ out:
     return result;
 }
 
-static int64_t try_fiemap(BlockDriverState *bs, off_t start, off_t *data,
+static int try_fiemap(BlockDriverState *bs, off_t start, off_t *data,
                           off_t *hole, int nb_sectors, int *pnum)
 {
 #ifdef CONFIG_FIEMAP
     BDRVRawState *s = bs->opaque;
-    int64_t ret = BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
+    int ret = 0;
     struct {
         struct fiemap fm;
         struct fiemap_extent fe;
@@ -1501,7 +1501,7 @@ static int64_t try_fiemap(BlockDriverState *bs, off_t start, off_t *data,
 #endif
 }
 
-static int64_t try_seek_hole(BlockDriverState *bs, off_t start, off_t *data,
+static int try_seek_hole(BlockDriverState *bs, off_t start, off_t *data,
                              off_t *hole, int *pnum)
 {
 #if defined SEEK_HOLE && defined SEEK_DATA
@@ -1526,7 +1526,7 @@ static int64_t try_seek_hole(BlockDriverState *bs, off_t start, off_t *data,
         }
     }
 
-    return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
+    return 0;
 #else
     return -ENOTSUP;
 #endif
@@ -1552,7 +1552,7 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
                                                     int nb_sectors, int *pnum)
 {
     off_t start, data = 0, hole = 0;
-    int64_t ret;
+    int ret;
 
     ret = fd_open(bs);
     if (ret < 0) {
@@ -1572,21 +1572,21 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
             /* Assume everything is allocated. */
             data = 0;
             hole = start + nb_sectors * BDRV_SECTOR_SIZE;
-            ret = BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
+            ret = 0;
         }
     }
 
+    assert(ret >= 0);
+
     if (data <= start) {
         /* On a data extent, compute sectors to the end of the extent.  */
         *pnum = MIN(nb_sectors, (hole - start) / BDRV_SECTOR_SIZE);
+        return ret | BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
     } else {
         /* On a hole, compute sectors to the beginning of the next extent.  */
         *pnum = MIN(nb_sectors, (data - start) / BDRV_SECTOR_SIZE);
-        ret &= ~BDRV_BLOCK_DATA;
-        ret |= BDRV_BLOCK_ZERO;
+        return ret | BDRV_BLOCK_ZERO | BDRV_BLOCK_OFFSET_VALID | start;
     }
-
-    return ret;
 }
 
 static coroutine_fn BlockDriverAIOCB *raw_aio_discard(BlockDriverState *bs,
-- 
2.1.0

Re: [Qemu-devel] [PATCH 2/2] raw-posix: raw_co_get_block_status() return value

[Max Reitz]

On 22.09.2014 17:23, Max Reitz wrote:
> Instead of generating the full return value thrice in try_fiemap(),
> try_seek_hole() and as a fall-back in raw_co_get_block_status() itself,
> generate the value only in raw_co_get_block_status().
>
> Suggested-by: Kevin Wolf <kwolf@redhat.com>
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   block/raw-posix.c | 20 ++++++++++----------
>   1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index de4e3f3..7e1cc02 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -1455,12 +1455,12 @@ out:
>       return result;
>   }
>   
> -static int64_t try_fiemap(BlockDriverState *bs, off_t start, off_t *data,
> +static int try_fiemap(BlockDriverState *bs, off_t start, off_t *data,
>                             off_t *hole, int nb_sectors, int *pnum)

Self-NACK, I always love to see alignment issues only after I already 
sent the series...

Max

>   {
>   #ifdef CONFIG_FIEMAP
>       BDRVRawState *s = bs->opaque;
> -    int64_t ret = BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
> +    int ret = 0;
>       struct {
>           struct fiemap fm;
>           struct fiemap_extent fe;
> @@ -1501,7 +1501,7 @@ static int64_t try_fiemap(BlockDriverState *bs, off_t start, off_t *data,
>   #endif
>   }
>   
> -static int64_t try_seek_hole(BlockDriverState *bs, off_t start, off_t *data,
> +static int try_seek_hole(BlockDriverState *bs, off_t start, off_t *data,
>                                off_t *hole, int *pnum)
>   {
>   #if defined SEEK_HOLE && defined SEEK_DATA
> @@ -1526,7 +1526,7 @@ static int64_t try_seek_hole(BlockDriverState *bs, off_t start, off_t *data,
>           }
>       }
>   
> -    return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
> +    return 0;
>   #else
>       return -ENOTSUP;
>   #endif
> @@ -1552,7 +1552,7 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
>                                                       int nb_sectors, int *pnum)
>   {
>       off_t start, data = 0, hole = 0;
> -    int64_t ret;
> +    int ret;
>   
>       ret = fd_open(bs);
>       if (ret < 0) {
> @@ -1572,21 +1572,21 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
>               /* Assume everything is allocated. */
>               data = 0;
>               hole = start + nb_sectors * BDRV_SECTOR_SIZE;
> -            ret = BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
> +            ret = 0;
>           }
>       }
>   
> +    assert(ret >= 0);
> +
>       if (data <= start) {
>           /* On a data extent, compute sectors to the end of the extent.  */
>           *pnum = MIN(nb_sectors, (hole - start) / BDRV_SECTOR_SIZE);
> +        return ret | BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
>       } else {
>           /* On a hole, compute sectors to the beginning of the next extent.  */
>           *pnum = MIN(nb_sectors, (data - start) / BDRV_SECTOR_SIZE);
> -        ret &= ~BDRV_BLOCK_DATA;
> -        ret |= BDRV_BLOCK_ZERO;
> +        return ret | BDRV_BLOCK_ZERO | BDRV_BLOCK_OFFSET_VALID | start;
>       }
> -
> -    return ret;
>   }
>   
>   static coroutine_fn BlockDriverAIOCB *raw_aio_discard(BlockDriverState *bs,

Re: [Qemu-devel] [PATCH 1/2] raw-posix: Fix raw_co_get_block_status() after EOF

[Benoît Canet]

The Monday 22 Sep 2014 à 17:23:44 (+0200), Max Reitz wrote :
> As its comment states, raw_co_get_block_status() should unconditionally
> return 0 and set *pnum to 0 for after EOF.
> 
> An assertion after lseek(..., SEEK_HOLE) tried to catch this case by
> asserting that errno != -ENXIO (which would indicate a position after
> the EOF); but it should be errno != ENXIO instead. Fix this, too.
> 
> Reported-by: Kevin Wolf <kwolf@redhat.com>
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block/raw-posix.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index a253697..de4e3f3 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -1509,9 +1509,9 @@ static int64_t try_seek_hole(BlockDriverState *bs, off_t start, off_t *data,
>  
>      *hole = lseek(s->fd, start, SEEK_HOLE);
>      if (*hole == -1) {
> -        /* -ENXIO indicates that sector_num was past the end of the file.
> +        /* ENXIO indicates that sector_num was past the end of the file.
>           * There is a virtual hole there.  */
> -        assert(errno != -ENXIO);
> +        assert(errno != ENXIO);
>  
>          return -errno;
>      }
> @@ -1560,6 +1560,10 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
>      }
>  
>      start = sector_num * BDRV_SECTOR_SIZE;
> +    if (start >= bdrv_getlength(bs)) {
> +        *pnum = 0;
> +        return 0;
> +    }
>  
>      ret = try_fiemap(bs, start, &data, &hole, nb_sectors, pnum);
>      if (ret < 0) {
> -- 
> 2.1.0
> 
> 
Reviewed-by: Benoît Canet <benoit.canet@nodalink.com>