[Qemu-devel] [PATCH v2 0/5] block: Drop BDS.filename

[Qemu-devel] [PATCH v2 0/5] block: Drop BDS.filename

[Max Reitz]

The BDS filename field is generally only used when opening disk images
or emitting error or warning messages, the only exception to this rule
is the map command of qemu-img. However, using exact_filename there
instead should not be a problem. Therefore, we can drop the filename
field from the BlockDriverState and use a function instead which builds
the filename from scratch when called.

This is slower than reading a static char array but the problem of that
static array is that it may become obsolete due to changes in any
BlockDriverState or in the BDS graph. Using a function which rebuilds
the filename every time it is called resolves this problem.

The disadvantage of worse performance is negligible, on the other hand.
After patch 2 of this series, which replaces some queries of
BDS.filename by reads from somewhere else (mostly BDS.exact_filename),
the filename field is only used when a disk image is opened or some
message should be emitted, both of which cases do not suffer from the
performance hit.


http://lists.nongnu.org/archive/html/qemu-devel/2015-06/msg07025.html
gives an example of how to achieve an outdated filename, so we do need
this series. We can technically fix it differently (by appropriately
invoking bdrv_refresh_filename()), but that is pretty difficult™. I find
this series simpler and it it's something we wanted to do anyway.

Regarding the fear that this might change current behavior, especially
for libvirt which used filenames to identify nodes in the BDS graph:
Since bdrv_open() already calls bdrv_refresh_filename() today, and
apparently everything works fine, this series will most likely not break
anything. The only thing that will change is if the BDS graph is
dynamically reconfigured at runtime, and in that case it's most likely a
bug fix. Also, I don't think libvirt supports such cases already.


tl;dr: This series is a bug fix and I don't think it'll break legacy
management applications relying on the filename to identify a BDS; as
long as they are not trying to continue that practice with more advanced
configurations (e.g. with Quorum).


v2:
- Rebased on master
- Added patch 5: Removes a TODO from iotest 041 and thus demonstrates a
  case where this series fixes something


git-backport-diff against v1:

Key:
[----] : patches are identical
[####] : number of functional differences between upstream/downstream patch
[down] : patch is downstream-only
The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively

001/5:[0015] [FC] 'block: Change bdrv_get_encrypted_filename()'
002/5:[0002] [FC] 'block: Avoid BlockDriverState.filename'
003/5:[----] [-C] 'block: Add bdrv_filename()'
004/5:[0038] [FC] 'block: Drop BlockDriverState.filename'
005/5:[down] 'iotests: Test changed Quorum filename'


Max Reitz (5):
  block: Change bdrv_get_encrypted_filename()
  block: Avoid BlockDriverState.filename
  block: Add bdrv_filename()
  block: Drop BlockDriverState.filename
  iotests: Test changed Quorum filename

 block.c                   | 91 ++++++++++++++++++++++++++++++++---------------
 block/commit.c            |  4 ++-
 block/gluster.c           |  2 +-
 block/mirror.c            | 14 +++++---
 block/qapi.c              |  5 +--
 block/raw-posix.c         | 16 +++++----
 block/raw-win32.c         |  4 +--
 block/raw_bsd.c           |  4 ++-
 block/vhdx-log.c          |  5 ++-
 block/vmdk.c              | 21 +++++++----
 block/vpc.c               |  6 ++--
 blockdev.c                | 21 ++++++++---
 include/block/block.h     |  3 +-
 include/block/block_int.h |  1 -
 monitor.c                 |  4 ++-
 qemu-img.c                |  2 +-
 tests/qemu-iotests/041    | 17 ++++++---
 17 files changed, 153 insertions(+), 67 deletions(-)

-- 
2.4.6

[Qemu-devel] [PATCH v2 1/5] block: Change bdrv_get_encrypted_filename()

[Max Reitz]

Instead of returning a pointer to the filename, copy it into a buffer
specified by the caller.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c               | 24 +++++++++++++++++-------
 include/block/block.h |  2 +-
 monitor.c             |  4 +++-
 3 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/block.c b/block.c
index d088ee0..e7dd2f1 100644
--- a/block.c
+++ b/block.c
@@ -2760,10 +2760,12 @@ void bdrv_add_key(BlockDriverState *bs, const char *key, Error **errp)
         }
     } else {
         if (bdrv_key_required(bs)) {
+            char enc_filename[PATH_MAX];
+            bdrv_get_encrypted_filename(bs, enc_filename, sizeof(enc_filename));
             error_set(errp, ERROR_CLASS_DEVICE_ENCRYPTED,
                       "'%s' (%s) is encrypted",
                       bdrv_get_device_or_node_name(bs),
-                      bdrv_get_encrypted_filename(bs));
+                      enc_filename);
         }
     }
 }
@@ -2980,14 +2982,22 @@ bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs)
     return false;
 }
 
-const char *bdrv_get_encrypted_filename(BlockDriverState *bs)
+char *bdrv_get_encrypted_filename(BlockDriverState *bs, char *dest, size_t sz)
 {
-    if (bs->backing_hd && bs->backing_hd->encrypted)
-        return bs->backing_file;
-    else if (bs->encrypted)
-        return bs->filename;
-    else
+    if (sz > INT_MAX) {
+        sz = INT_MAX;
+    }
+
+    if (bs->backing_hd && bs->backing_hd->encrypted) {
+        pstrcpy(dest, sz, bs->backing_file);
+        return dest;
+    } else if (bs->encrypted) {
+        pstrcpy(dest, sz, bs->filename);
+        return dest;
+    } else {
+        dest[0] = '\0';
         return NULL;
+    }
 }
 
 void bdrv_get_backing_filename(BlockDriverState *bs,
diff --git a/include/block/block.h b/include/block/block.h
index 37916f7..a78e4f1 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -430,7 +430,7 @@ void bdrv_round_to_clusters(BlockDriverState *bs,
                             int64_t *cluster_sector_num,
                             int *cluster_nb_sectors);
 
-const char *bdrv_get_encrypted_filename(BlockDriverState *bs);
+char *bdrv_get_encrypted_filename(BlockDriverState *bs, char *dest, size_t sz);
 void bdrv_get_backing_filename(BlockDriverState *bs,
                                char *filename, int filename_size);
 void bdrv_get_full_backing_filename(BlockDriverState *bs,
diff --git a/monitor.c b/monitor.c
index aeea2b5..cfdf781 100644
--- a/monitor.c
+++ b/monitor.c
@@ -5292,10 +5292,12 @@ int monitor_read_bdrv_key_start(Monitor *mon, BlockDriverState *bs,
                                 BlockCompletionFunc *completion_cb,
                                 void *opaque)
 {
+    char enc_filename[PATH_MAX];
     int err;
 
+    bdrv_get_encrypted_filename(bs, enc_filename, sizeof(enc_filename));
     monitor_printf(mon, "%s (%s) is encrypted.\n", bdrv_get_device_name(bs),
-                   bdrv_get_encrypted_filename(bs));
+                   enc_filename);
 
     mon->password_completion_cb = completion_cb;
     mon->password_opaque = opaque;
-- 
2.4.6

Re: [Qemu-devel] [PATCH v2 1/5] block: Change bdrv_get_encrypted_filename()

[Wen Congyang]

On 08/06/2015 04:52 AM, Max Reitz wrote:
> Instead of returning a pointer to the filename, copy it into a buffer
> specified by the caller.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block.c               | 24 +++++++++++++++++-------
>  include/block/block.h |  2 +-
>  monitor.c             |  4 +++-
>  3 files changed, 21 insertions(+), 9 deletions(-)
> 
> diff --git a/block.c b/block.c
> index d088ee0..e7dd2f1 100644
> --- a/block.c
> +++ b/block.c
> @@ -2760,10 +2760,12 @@ void bdrv_add_key(BlockDriverState *bs, const char *key, Error **errp)
>          }
>      } else {
>          if (bdrv_key_required(bs)) {
> +            char enc_filename[PATH_MAX];

I think it's better to use g_malloc() here.

> +            bdrv_get_encrypted_filename(bs, enc_filename, sizeof(enc_filename));
>              error_set(errp, ERROR_CLASS_DEVICE_ENCRYPTED,
>                        "'%s' (%s) is encrypted",
>                        bdrv_get_device_or_node_name(bs),
> -                      bdrv_get_encrypted_filename(bs));
> +                      enc_filename);
>          }
>      }
>  }
> @@ -2980,14 +2982,22 @@ bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs)
>      return false;
>  }
>  
> -const char *bdrv_get_encrypted_filename(BlockDriverState *bs)
> +char *bdrv_get_encrypted_filename(BlockDriverState *bs, char *dest, size_t sz)
>  {
> -    if (bs->backing_hd && bs->backing_hd->encrypted)
> -        return bs->backing_file;
> -    else if (bs->encrypted)
> -        return bs->filename;
> -    else
> +    if (sz > INT_MAX) {
> +        sz = INT_MAX;
> +    }
> +
> +    if (bs->backing_hd && bs->backing_hd->encrypted) {
> +        pstrcpy(dest, sz, bs->backing_file);
> +        return dest;
> +    } else if (bs->encrypted) {
> +        pstrcpy(dest, sz, bs->filename);
> +        return dest;
> +    } else {
> +        dest[0] = '\0';
>          return NULL;
> +    }
>  }
>  
>  void bdrv_get_backing_filename(BlockDriverState *bs,
> diff --git a/include/block/block.h b/include/block/block.h
> index 37916f7..a78e4f1 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -430,7 +430,7 @@ void bdrv_round_to_clusters(BlockDriverState *bs,
>                              int64_t *cluster_sector_num,
>                              int *cluster_nb_sectors);
>  
> -const char *bdrv_get_encrypted_filename(BlockDriverState *bs);
> +char *bdrv_get_encrypted_filename(BlockDriverState *bs, char *dest, size_t sz);
>  void bdrv_get_backing_filename(BlockDriverState *bs,
>                                 char *filename, int filename_size);
>  void bdrv_get_full_backing_filename(BlockDriverState *bs,
> diff --git a/monitor.c b/monitor.c
> index aeea2b5..cfdf781 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -5292,10 +5292,12 @@ int monitor_read_bdrv_key_start(Monitor *mon, BlockDriverState *bs,
>                                  BlockCompletionFunc *completion_cb,
>                                  void *opaque)
>  {
> +    char enc_filename[PATH_MAX];

same too.

Thanks
Wen Congyang

>      int err;
>  
> +    bdrv_get_encrypted_filename(bs, enc_filename, sizeof(enc_filename));
>      monitor_printf(mon, "%s (%s) is encrypted.\n", bdrv_get_device_name(bs),
> -                   bdrv_get_encrypted_filename(bs));
> +                   enc_filename);
>  
>      mon->password_completion_cb = completion_cb;
>      mon->password_opaque = opaque;
> 

Re: [Qemu-devel] [PATCH v2 1/5] block: Change bdrv_get_encrypted_filename()

[Max Reitz]

On 06.08.2015 04:01, Wen Congyang wrote:
> On 08/06/2015 04:52 AM, Max Reitz wrote:
>> Instead of returning a pointer to the filename, copy it into a buffer
>> specified by the caller.
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> ---
>>   block.c               | 24 +++++++++++++++++-------
>>   include/block/block.h |  2 +-
>>   monitor.c             |  4 +++-
>>   3 files changed, 21 insertions(+), 9 deletions(-)
>>
>> diff --git a/block.c b/block.c
>> index d088ee0..e7dd2f1 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -2760,10 +2760,12 @@ void bdrv_add_key(BlockDriverState *bs, const char *key, Error **errp)
>>           }
>>       } else {
>>           if (bdrv_key_required(bs)) {
>> +            char enc_filename[PATH_MAX];
>
> I think it's better to use g_malloc() here.
>
>> +            bdrv_get_encrypted_filename(bs, enc_filename, sizeof(enc_filename));
>>               error_set(errp, ERROR_CLASS_DEVICE_ENCRYPTED,
>>                         "'%s' (%s) is encrypted",
>>                         bdrv_get_device_or_node_name(bs),
>> -                      bdrv_get_encrypted_filename(bs));
>> +                      enc_filename);
>>           }
>>       }
>>   }
>> @@ -2980,14 +2982,22 @@ bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs)
>>       return false;
>>   }
>>
>> -const char *bdrv_get_encrypted_filename(BlockDriverState *bs)
>> +char *bdrv_get_encrypted_filename(BlockDriverState *bs, char *dest, size_t sz)
>>   {
>> -    if (bs->backing_hd && bs->backing_hd->encrypted)
>> -        return bs->backing_file;
>> -    else if (bs->encrypted)
>> -        return bs->filename;
>> -    else
>> +    if (sz > INT_MAX) {
>> +        sz = INT_MAX;
>> +    }
>> +
>> +    if (bs->backing_hd && bs->backing_hd->encrypted) {
>> +        pstrcpy(dest, sz, bs->backing_file);
>> +        return dest;
>> +    } else if (bs->encrypted) {
>> +        pstrcpy(dest, sz, bs->filename);
>> +        return dest;
>> +    } else {
>> +        dest[0] = '\0';
>>           return NULL;
>> +    }
>>   }
>>
>>   void bdrv_get_backing_filename(BlockDriverState *bs,
>> diff --git a/include/block/block.h b/include/block/block.h
>> index 37916f7..a78e4f1 100644
>> --- a/include/block/block.h
>> +++ b/include/block/block.h
>> @@ -430,7 +430,7 @@ void bdrv_round_to_clusters(BlockDriverState *bs,
>>                               int64_t *cluster_sector_num,
>>                               int *cluster_nb_sectors);
>>
>> -const char *bdrv_get_encrypted_filename(BlockDriverState *bs);
>> +char *bdrv_get_encrypted_filename(BlockDriverState *bs, char *dest, size_t sz);
>>   void bdrv_get_backing_filename(BlockDriverState *bs,
>>                                  char *filename, int filename_size);
>>   void bdrv_get_full_backing_filename(BlockDriverState *bs,
>> diff --git a/monitor.c b/monitor.c
>> index aeea2b5..cfdf781 100644
>> --- a/monitor.c
>> +++ b/monitor.c
>> @@ -5292,10 +5292,12 @@ int monitor_read_bdrv_key_start(Monitor *mon, BlockDriverState *bs,
>>                                   BlockCompletionFunc *completion_cb,
>>                                   void *opaque)
>>   {
>> +    char enc_filename[PATH_MAX];
>
> same too.

You're right. I'll change it (in every patch of this series that pattern 
appears in).

Thanks for reviewing!

Max

>
> Thanks
> Wen Congyang
>
>>       int err;
>>
>> +    bdrv_get_encrypted_filename(bs, enc_filename, sizeof(enc_filename));
>>       monitor_printf(mon, "%s (%s) is encrypted.\n", bdrv_get_device_name(bs),
>> -                   bdrv_get_encrypted_filename(bs));
>> +                   enc_filename);
>>
>>       mon->password_completion_cb = completion_cb;
>>       mon->password_opaque = opaque;
>>
>

[Qemu-devel] [PATCH v2 2/5] block: Avoid BlockDriverState.filename

[Max Reitz]

In places which directly pass a filename to the OS, we should not use
the filename field at all but exact_filename instead (although the
former currently equals the latter if that is set).

In qemu-img's map command, we should be using the filename field; but
since this commit prepares to remove that field, using exact_filename is
fine, too (this is the only user of BlockDriverState.filename which
frequently queries that field).

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c           | 4 ++--
 block/gluster.c   | 2 +-
 block/raw-posix.c | 8 ++++----
 block/raw-win32.c | 4 ++--
 qemu-img.c        | 2 +-
 5 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/block.c b/block.c
index e7dd2f1..5a1dc16 100644
--- a/block.c
+++ b/block.c
@@ -918,8 +918,8 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
     if (ret < 0) {
         if (local_err) {
             error_propagate(errp, local_err);
-        } else if (bs->filename[0]) {
-            error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename);
+        } else if (bs->exact_filename[0]) {
+            error_setg_errno(errp, -ret, "Could not open '%s'", bs->exact_filename);
         } else {
             error_setg_errno(errp, -ret, "Could not open image");
         }
diff --git a/block/gluster.c b/block/gluster.c
index 1eb3a8c..176682b 100644
--- a/block/gluster.c
+++ b/block/gluster.c
@@ -358,7 +358,7 @@ static int qemu_gluster_reopen_prepare(BDRVReopenState *state,
 
     gconf = g_new0(GlusterConf, 1);
 
-    reop_s->glfs = qemu_gluster_init(gconf, state->bs->filename, errp);
+    reop_s->glfs = qemu_gluster_init(gconf, state->bs->exact_filename, errp);
     if (reop_s->glfs == NULL) {
         ret = -errno;
         goto exit;
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 855febe..b61c11f 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -671,7 +671,7 @@ static int raw_reopen_prepare(BDRVReopenState *state,
     /* If we cannot use fcntl, or fcntl failed, fall back to qemu_open() */
     if (raw_s->fd == -1) {
         assert(!(raw_s->open_flags & O_CREAT));
-        raw_s->fd = qemu_open(state->bs->filename, raw_s->open_flags);
+        raw_s->fd = qemu_open(state->bs->exact_filename, raw_s->open_flags);
         if (raw_s->fd == -1) {
             error_setg_errno(errp, errno, "Could not reopen file");
             ret = -1;
@@ -2195,7 +2195,7 @@ static int fd_open(BlockDriverState *bs)
             DPRINTF("No floppy (open delayed)\n");
             return -EIO;
         }
-        s->fd = qemu_open(bs->filename, s->open_flags & ~O_NONBLOCK);
+        s->fd = qemu_open(bs->exact_filename, s->open_flags & ~O_NONBLOCK);
         if (s->fd < 0) {
             s->fd_error_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
             s->fd_got_error = 1;
@@ -2486,7 +2486,7 @@ static void floppy_eject(BlockDriverState *bs, bool eject_flag)
         qemu_close(s->fd);
         s->fd = -1;
     }
-    fd = qemu_open(bs->filename, s->open_flags | O_NONBLOCK);
+    fd = qemu_open(bs->exact_filename, s->open_flags | O_NONBLOCK);
     if (fd >= 0) {
         if (ioctl(fd, FDEJECT, 0) < 0)
             perror("FDEJECT");
@@ -2710,7 +2710,7 @@ static int cdrom_reopen(BlockDriverState *bs)
      */
     if (s->fd >= 0)
         qemu_close(s->fd);
-    fd = qemu_open(bs->filename, s->open_flags, 0644);
+    fd = qemu_open(bs->exact_filename, s->open_flags, 0644);
     if (fd < 0) {
         s->fd = -1;
         return -EIO;
diff --git a/block/raw-win32.c b/block/raw-win32.c
index 68f2338..5c8a894 100644
--- a/block/raw-win32.c
+++ b/block/raw-win32.c
@@ -417,7 +417,7 @@ static void raw_close(BlockDriverState *bs)
 
     CloseHandle(s->hfile);
     if (bs->open_flags & BDRV_O_TEMPORARY) {
-        unlink(bs->filename);
+        unlink(bs->exact_filename);
     }
 }
 
@@ -485,7 +485,7 @@ static int64_t raw_get_allocated_file_size(BlockDriverState *bs)
                                               DWORD * high);
     get_compressed_t get_compressed;
     struct _stati64 st;
-    const char *filename = bs->filename;
+    const char *filename = bs->exact_filename;
     /* WinNT support GetCompressedFileSize to determine allocate size */
     get_compressed =
         (get_compressed_t) GetProcAddress(GetModuleHandle("kernel32"),
diff --git a/qemu-img.c b/qemu-img.c
index 75f4ee4..3d5587a 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2155,7 +2155,7 @@ static void dump_map_entry(OutputFormat output_format, MapEntry *e,
         }
         if ((e->flags & (BDRV_BLOCK_DATA|BDRV_BLOCK_ZERO)) == BDRV_BLOCK_DATA) {
             printf("%#-16"PRIx64"%#-16"PRIx64"%#-16"PRIx64"%s\n",
-                   e->start, e->length, e->offset, e->bs->filename);
+                   e->start, e->length, e->offset, e->bs->exact_filename);
         }
         /* This format ignores the distinction between 0, ZERO and ZERO|DATA.
          * Modify the flags here to allow more coalescing.
-- 
2.4.6

Re: [Qemu-devel] [PATCH v2 2/5] block: Avoid BlockDriverState.filename

[Wen Congyang]

On 08/06/2015 04:52 AM, Max Reitz wrote:
> In places which directly pass a filename to the OS, we should not use
> the filename field at all but exact_filename instead (although the
> former currently equals the latter if that is set).
> 
> In qemu-img's map command, we should be using the filename field; but
> since this commit prepares to remove that field, using exact_filename is
> fine, too (this is the only user of BlockDriverState.filename which
> frequently queries that field).
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block.c           | 4 ++--
>  block/gluster.c   | 2 +-
>  block/raw-posix.c | 8 ++++----
>  block/raw-win32.c | 4 ++--
>  qemu-img.c        | 2 +-
>  5 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/block.c b/block.c
> index e7dd2f1..5a1dc16 100644
> --- a/block.c
> +++ b/block.c
> @@ -918,8 +918,8 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
>      if (ret < 0) {
>          if (local_err) {
>              error_propagate(errp, local_err);
> -        } else if (bs->filename[0]) {
> -            error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename);
> +        } else if (bs->exact_filename[0]) {
> +            error_setg_errno(errp, -ret, "Could not open '%s'", bs->exact_filename);
>          } else {
>              error_setg_errno(errp, -ret, "Could not open image");
>          }
> diff --git a/block/gluster.c b/block/gluster.c
> index 1eb3a8c..176682b 100644
> --- a/block/gluster.c
> +++ b/block/gluster.c
> @@ -358,7 +358,7 @@ static int qemu_gluster_reopen_prepare(BDRVReopenState *state,
>  
>      gconf = g_new0(GlusterConf, 1);
>  
> -    reop_s->glfs = qemu_gluster_init(gconf, state->bs->filename, errp);
> +    reop_s->glfs = qemu_gluster_init(gconf, state->bs->exact_filename, errp);
>      if (reop_s->glfs == NULL) {
>          ret = -errno;
>          goto exit;
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index 855febe..b61c11f 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -671,7 +671,7 @@ static int raw_reopen_prepare(BDRVReopenState *state,
>      /* If we cannot use fcntl, or fcntl failed, fall back to qemu_open() */
>      if (raw_s->fd == -1) {
>          assert(!(raw_s->open_flags & O_CREAT));
> -        raw_s->fd = qemu_open(state->bs->filename, raw_s->open_flags);
> +        raw_s->fd = qemu_open(state->bs->exact_filename, raw_s->open_flags);

In raw_open_common(), we call raw_normalize_devicepath(). Why don't we call it
here?

Thanks
Wen Congyang

>          if (raw_s->fd == -1) {
>              error_setg_errno(errp, errno, "Could not reopen file");
>              ret = -1;
> @@ -2195,7 +2195,7 @@ static int fd_open(BlockDriverState *bs)
>              DPRINTF("No floppy (open delayed)\n");
>              return -EIO;
>          }
> -        s->fd = qemu_open(bs->filename, s->open_flags & ~O_NONBLOCK);
> +        s->fd = qemu_open(bs->exact_filename, s->open_flags & ~O_NONBLOCK);
>          if (s->fd < 0) {
>              s->fd_error_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
>              s->fd_got_error = 1;
> @@ -2486,7 +2486,7 @@ static void floppy_eject(BlockDriverState *bs, bool eject_flag)
>          qemu_close(s->fd);
>          s->fd = -1;
>      }
> -    fd = qemu_open(bs->filename, s->open_flags | O_NONBLOCK);
> +    fd = qemu_open(bs->exact_filename, s->open_flags | O_NONBLOCK);
>      if (fd >= 0) {
>          if (ioctl(fd, FDEJECT, 0) < 0)
>              perror("FDEJECT");
> @@ -2710,7 +2710,7 @@ static int cdrom_reopen(BlockDriverState *bs)
>       */
>      if (s->fd >= 0)
>          qemu_close(s->fd);
> -    fd = qemu_open(bs->filename, s->open_flags, 0644);
> +    fd = qemu_open(bs->exact_filename, s->open_flags, 0644);
>      if (fd < 0) {
>          s->fd = -1;
>          return -EIO;
> diff --git a/block/raw-win32.c b/block/raw-win32.c
> index 68f2338..5c8a894 100644
> --- a/block/raw-win32.c
> +++ b/block/raw-win32.c
> @@ -417,7 +417,7 @@ static void raw_close(BlockDriverState *bs)
>  
>      CloseHandle(s->hfile);
>      if (bs->open_flags & BDRV_O_TEMPORARY) {
> -        unlink(bs->filename);
> +        unlink(bs->exact_filename);
>      }
>  }
>  
> @@ -485,7 +485,7 @@ static int64_t raw_get_allocated_file_size(BlockDriverState *bs)
>                                                DWORD * high);
>      get_compressed_t get_compressed;
>      struct _stati64 st;
> -    const char *filename = bs->filename;
> +    const char *filename = bs->exact_filename;
>      /* WinNT support GetCompressedFileSize to determine allocate size */
>      get_compressed =
>          (get_compressed_t) GetProcAddress(GetModuleHandle("kernel32"),
> diff --git a/qemu-img.c b/qemu-img.c
> index 75f4ee4..3d5587a 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -2155,7 +2155,7 @@ static void dump_map_entry(OutputFormat output_format, MapEntry *e,
>          }
>          if ((e->flags & (BDRV_BLOCK_DATA|BDRV_BLOCK_ZERO)) == BDRV_BLOCK_DATA) {
>              printf("%#-16"PRIx64"%#-16"PRIx64"%#-16"PRIx64"%s\n",
> -                   e->start, e->length, e->offset, e->bs->filename);
> +                   e->start, e->length, e->offset, e->bs->exact_filename);
>          }
>          /* This format ignores the distinction between 0, ZERO and ZERO|DATA.
>           * Modify the flags here to allow more coalescing.
> 

Re: [Qemu-devel] [PATCH v2 2/5] block: Avoid BlockDriverState.filename

[Max Reitz]

On 06.08.2015 04:27, Wen Congyang wrote:
> On 08/06/2015 04:52 AM, Max Reitz wrote:
>> In places which directly pass a filename to the OS, we should not use
>> the filename field at all but exact_filename instead (although the
>> former currently equals the latter if that is set).
>>
>> In qemu-img's map command, we should be using the filename field; but
>> since this commit prepares to remove that field, using exact_filename is
>> fine, too (this is the only user of BlockDriverState.filename which
>> frequently queries that field).
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> ---
>>   block.c           | 4 ++--
>>   block/gluster.c   | 2 +-
>>   block/raw-posix.c | 8 ++++----
>>   block/raw-win32.c | 4 ++--
>>   qemu-img.c        | 2 +-
>>   5 files changed, 10 insertions(+), 10 deletions(-)
>>
>> diff --git a/block.c b/block.c
>> index e7dd2f1..5a1dc16 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -918,8 +918,8 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
>>       if (ret < 0) {
>>           if (local_err) {
>>               error_propagate(errp, local_err);
>> -        } else if (bs->filename[0]) {
>> -            error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename);
>> +        } else if (bs->exact_filename[0]) {
>> +            error_setg_errno(errp, -ret, "Could not open '%s'", bs->exact_filename);
>>           } else {
>>               error_setg_errno(errp, -ret, "Could not open image");
>>           }
>> diff --git a/block/gluster.c b/block/gluster.c
>> index 1eb3a8c..176682b 100644
>> --- a/block/gluster.c
>> +++ b/block/gluster.c
>> @@ -358,7 +358,7 @@ static int qemu_gluster_reopen_prepare(BDRVReopenState *state,
>>
>>       gconf = g_new0(GlusterConf, 1);
>>
>> -    reop_s->glfs = qemu_gluster_init(gconf, state->bs->filename, errp);
>> +    reop_s->glfs = qemu_gluster_init(gconf, state->bs->exact_filename, errp);
>>       if (reop_s->glfs == NULL) {
>>           ret = -errno;
>>           goto exit;
>> diff --git a/block/raw-posix.c b/block/raw-posix.c
>> index 855febe..b61c11f 100644
>> --- a/block/raw-posix.c
>> +++ b/block/raw-posix.c
>> @@ -671,7 +671,7 @@ static int raw_reopen_prepare(BDRVReopenState *state,
>>       /* If we cannot use fcntl, or fcntl failed, fall back to qemu_open() */
>>       if (raw_s->fd == -1) {
>>           assert(!(raw_s->open_flags & O_CREAT));
>> -        raw_s->fd = qemu_open(state->bs->filename, raw_s->open_flags);
>> +        raw_s->fd = qemu_open(state->bs->exact_filename, raw_s->open_flags);
>
> In raw_open_common(), we call raw_normalize_devicepath(). Why don't we call it
> here?

Ideally because bs->exact_filename is normalized already, whereas 
raw_open_common() takes the filename from the options QDict (which was 
specified by the user). The question now is whether bs->exact_filename 
is indeed normalized.

Looking into bdrv_open_common(), where that field is initially set, it 
doesn't look that way.

One way to fix this would be to implement bdrv_refresh_filename() for 
raw-posix. However, then we still have the issue of bs->filename usage 
in raw_open_common() (for an error message, although in reality, that 
message can only appear on Linux where raw_normalize_devicepath() won't 
do anything).

So the easy way to fix it would be to copy the normalized filename into 
bs->filename at the beginning of raw_open_common(). I'll think about it, 
but in any case, I think this issue is not related to this series and 
the fix will work independently.

I'll work something out, thanks for spotting this!

Max

>
> Thanks
> Wen Congyang
>
>>           if (raw_s->fd == -1) {
>>               error_setg_errno(errp, errno, "Could not reopen file");
>>               ret = -1;
>> @@ -2195,7 +2195,7 @@ static int fd_open(BlockDriverState *bs)
>>               DPRINTF("No floppy (open delayed)\n");
>>               return -EIO;
>>           }
>> -        s->fd = qemu_open(bs->filename, s->open_flags & ~O_NONBLOCK);
>> +        s->fd = qemu_open(bs->exact_filename, s->open_flags & ~O_NONBLOCK);
>>           if (s->fd < 0) {
>>               s->fd_error_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
>>               s->fd_got_error = 1;
>> @@ -2486,7 +2486,7 @@ static void floppy_eject(BlockDriverState *bs, bool eject_flag)
>>           qemu_close(s->fd);
>>           s->fd = -1;
>>       }
>> -    fd = qemu_open(bs->filename, s->open_flags | O_NONBLOCK);
>> +    fd = qemu_open(bs->exact_filename, s->open_flags | O_NONBLOCK);
>>       if (fd >= 0) {
>>           if (ioctl(fd, FDEJECT, 0) < 0)
>>               perror("FDEJECT");
>> @@ -2710,7 +2710,7 @@ static int cdrom_reopen(BlockDriverState *bs)
>>        */
>>       if (s->fd >= 0)
>>           qemu_close(s->fd);
>> -    fd = qemu_open(bs->filename, s->open_flags, 0644);
>> +    fd = qemu_open(bs->exact_filename, s->open_flags, 0644);
>>       if (fd < 0) {
>>           s->fd = -1;
>>           return -EIO;
>> diff --git a/block/raw-win32.c b/block/raw-win32.c
>> index 68f2338..5c8a894 100644
>> --- a/block/raw-win32.c
>> +++ b/block/raw-win32.c
>> @@ -417,7 +417,7 @@ static void raw_close(BlockDriverState *bs)
>>
>>       CloseHandle(s->hfile);
>>       if (bs->open_flags & BDRV_O_TEMPORARY) {
>> -        unlink(bs->filename);
>> +        unlink(bs->exact_filename);
>>       }
>>   }
>>
>> @@ -485,7 +485,7 @@ static int64_t raw_get_allocated_file_size(BlockDriverState *bs)
>>                                                 DWORD * high);
>>       get_compressed_t get_compressed;
>>       struct _stati64 st;
>> -    const char *filename = bs->filename;
>> +    const char *filename = bs->exact_filename;
>>       /* WinNT support GetCompressedFileSize to determine allocate size */
>>       get_compressed =
>>           (get_compressed_t) GetProcAddress(GetModuleHandle("kernel32"),
>> diff --git a/qemu-img.c b/qemu-img.c
>> index 75f4ee4..3d5587a 100644
>> --- a/qemu-img.c
>> +++ b/qemu-img.c
>> @@ -2155,7 +2155,7 @@ static void dump_map_entry(OutputFormat output_format, MapEntry *e,
>>           }
>>           if ((e->flags & (BDRV_BLOCK_DATA|BDRV_BLOCK_ZERO)) == BDRV_BLOCK_DATA) {
>>               printf("%#-16"PRIx64"%#-16"PRIx64"%#-16"PRIx64"%s\n",
>> -                   e->start, e->length, e->offset, e->bs->filename);
>> +                   e->start, e->length, e->offset, e->bs->exact_filename);
>>           }
>>           /* This format ignores the distinction between 0, ZERO and ZERO|DATA.
>>            * Modify the flags here to allow more coalescing.
>>
>

[Qemu-devel] [PATCH v2 3/5] block: Add bdrv_filename()

[Max Reitz]

Split the part which actually refreshes the BlockDriverState.filename
field off of bdrv_refresh_filename() into a more generic function
bdrv_filename(), which first calls bdrv_refresh_filename() and then
stores a qemu-usable filename into the given buffer instead of
BlockDriverState.filename.

Since bdrv_refresh_filename() therefore no longer refreshes that field,
some calls to that function have to be replaced by calls to
bdrv_filename() "manually" refreshing the BDS filename field (this is
only temporary).

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c               | 31 ++++++++++++++++++++++++-------
 block/blkverify.c     |  3 ++-
 block/quorum.c        |  2 +-
 include/block/block.h |  1 +
 4 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/block.c b/block.c
index 5a1dc16..cbc53e2 100644
--- a/block.c
+++ b/block.c
@@ -1558,7 +1558,7 @@ static int bdrv_open_inherit(BlockDriverState **pbs, const char *filename,
         }
     }
 
-    bdrv_refresh_filename(bs);
+    bdrv_filename(bs, bs->filename, sizeof(bs->filename));
 
     /* For snapshot=on, create a temporary qcow2 overlay. bs points to the
      * temporary snapshot afterwards. */
@@ -4151,9 +4151,6 @@ static bool append_open_options(QDict *d, BlockDriverState *bs)
  *  - full_open_options: Options which, when given when opening a block device
  *                       (without a filename), result in a BDS (mostly)
  *                       equalling the given one
- *  - filename: If exact_filename is set, it is copied here. Otherwise,
- *              full_open_options is converted to a JSON object, prefixed with
- *              "json:" (for use through the JSON pseudo protocol) and put here.
  */
 void bdrv_refresh_filename(BlockDriverState *bs)
 {
@@ -4240,15 +4237,35 @@ void bdrv_refresh_filename(BlockDriverState *bs)
 
         bs->full_open_options = opts;
     }
+}
+
+/* First refreshes exact_filename and full_open_options by calling
+ * bdrv_refresh_filename(). Then, if exact_filename is set, it is copied into
+ * the target buffer. Otherwise, full_open_options is converted to a JSON
+ * object, prefixed with "json:" (for use through the JSON pseudo protocol) and
+ * put there.
+ *
+ * If sz > 0, the string put into the buffer will always be null-terminated.
+ *
+ * Returns @dest.
+ */
+char *bdrv_filename(BlockDriverState *bs, char *dest, size_t sz)
+{
+    bdrv_refresh_filename(bs);
+
+    if (sz > INT_MAX) {
+        sz = INT_MAX;
+    }
 
     if (bs->exact_filename[0]) {
-        pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename);
+        pstrcpy(dest, sz, bs->exact_filename);
     } else if (bs->full_open_options) {
         QString *json = qobject_to_json(QOBJECT(bs->full_open_options));
-        snprintf(bs->filename, sizeof(bs->filename), "json:%s",
-                 qstring_get_str(json));
+        snprintf(dest, sz, "json:%s", qstring_get_str(json));
         QDECREF(json);
     }
+
+    return dest;
 }
 
 /* This accessor function purpose is to allow the device models to access the
diff --git a/block/blkverify.c b/block/blkverify.c
index d277e63..cb9ce02 100644
--- a/block/blkverify.c
+++ b/block/blkverify.c
@@ -309,7 +309,8 @@ static void blkverify_refresh_filename(BlockDriverState *bs)
     BDRVBlkverifyState *s = bs->opaque;
 
     /* bs->file has already been refreshed */
-    bdrv_refresh_filename(s->test_file);
+    bdrv_filename(s->test_file, s->test_file->filename,
+                  sizeof(s->test_file->filename));
 
     if (bs->file->full_open_options && s->test_file->full_open_options) {
         QDict *opts = qdict_new();
diff --git a/block/quorum.c b/block/quorum.c
index 2f6c45f..00d1fb0 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1003,7 +1003,7 @@ static void quorum_refresh_filename(BlockDriverState *bs)
     int i;
 
     for (i = 0; i < s->num_children; i++) {
-        bdrv_refresh_filename(s->bs[i]);
+        bdrv_filename(s->bs[i], s->bs[i]->filename, sizeof(s->bs[i]->filename));
         if (!s->bs[i]->full_open_options) {
             return;
         }
diff --git a/include/block/block.h b/include/block/block.h
index a78e4f1..263442e 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -267,6 +267,7 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
     const char *backing_file);
 int bdrv_get_backing_file_depth(BlockDriverState *bs);
 void bdrv_refresh_filename(BlockDriverState *bs);
+char *bdrv_filename(BlockDriverState *bs, char *dest, size_t sz);
 int bdrv_truncate(BlockDriverState *bs, int64_t offset);
 int64_t bdrv_nb_sectors(BlockDriverState *bs);
 int64_t bdrv_getlength(BlockDriverState *bs);
-- 
2.4.6

[Qemu-devel] [PATCH v2 4/5] block: Drop BlockDriverState.filename

[Max Reitz]

That field is now only used during initialization of BlockDriverStates
(opening images) and for error or warning messages. Performance is not
that much of an issue here, so we can drop the field and replace its use
by a call to bdrv_filename(). By doing so we can ensure the result
always to be recent, whereas the contents of BlockDriverState.filename
may have been obsoleted by manipulations of single BlockDriverStates or
of the BDS graph.

The users of the BDS filename field were changed as follows:
- copying the filename into another buffer is trivially replaced by
  using bdrv_filename() instead of the copy function
- strdup() on the filename is replaced by a call to bdrv_filename() on a
  newly allocated heap buffer
- bdrv_filename(bs, bs->filename, sizeof(bs->filename)) is replaced by
  bdrv_refresh_filename(bs)
  (these were introduced by the previous patch)
- anywhere else a buffer is created on the stack to hold the result of
  bdrv_filename(); any access to BlockDriverState.filename is then
  replaced by this buffer

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c                   | 40 ++++++++++++++++++++++++----------------
 block/blkverify.c         |  3 +--
 block/commit.c            |  4 +++-
 block/mirror.c            | 14 ++++++++++----
 block/qapi.c              |  5 +++--
 block/quorum.c            |  2 +-
 block/raw-posix.c         |  8 ++++++--
 block/raw_bsd.c           |  4 +++-
 block/vhdx-log.c          |  5 ++++-
 block/vmdk.c              | 21 +++++++++++++++------
 block/vpc.c               |  6 ++++--
 blockdev.c                | 21 ++++++++++++++++-----
 include/block/block_int.h |  1 -
 13 files changed, 90 insertions(+), 44 deletions(-)

diff --git a/block.c b/block.c
index cbc53e2..30ae243 100644
--- a/block.c
+++ b/block.c
@@ -227,8 +227,8 @@ void bdrv_get_full_backing_filename_from_filename(const char *backed,
 void bdrv_get_full_backing_filename(BlockDriverState *bs, char *dest, size_t sz,
                                     Error **errp)
 {
-    char *backed = bs->exact_filename[0] ? bs->exact_filename : bs->filename;
-
+    char backed[PATH_MAX];
+    bdrv_filename(bs, backed, sizeof(backed));
     bdrv_get_full_backing_filename_from_filename(backed, bs->backing_file,
                                                  dest, sz, errp);
 }
@@ -821,6 +821,7 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
     QDict *options, int flags, BlockDriver *drv, Error **errp)
 {
     int ret, open_flags;
+    char filename_buffer[PATH_MAX];
     const char *filename;
     const char *node_name = NULL;
     QemuOpts *opts;
@@ -831,7 +832,8 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
     assert(options != NULL && bs->options != options);
 
     if (file != NULL) {
-        filename = file->filename;
+        filename = bdrv_filename(file,
+                                 filename_buffer, sizeof(filename_buffer));
     } else {
         filename = qdict_get_try_str(options, "filename");
     }
@@ -888,11 +890,10 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
     }
 
     if (filename != NULL) {
-        pstrcpy(bs->filename, sizeof(bs->filename), filename);
+        pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), filename);
     } else {
-        bs->filename[0] = '\0';
+        bs->exact_filename[0] = '\0';
     }
-    pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename);
 
     bs->drv = drv;
     bs->opaque = g_malloc0(drv->instance_size);
@@ -1157,7 +1158,7 @@ void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
     }
     bs->backing_child = bdrv_attach_child(bs, backing_hd, &child_backing);
     bs->open_flags &= ~BDRV_O_NO_BACKING;
-    pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_hd->filename);
+    bdrv_filename(backing_hd, bs->backing_file, sizeof(bs->backing_file));
     pstrcpy(bs->backing_format, sizeof(bs->backing_format),
             backing_hd->drv ? backing_hd->drv->format_name : "");
 
@@ -1558,7 +1559,7 @@ static int bdrv_open_inherit(BlockDriverState **pbs, const char *filename,
         }
     }
 
-    bdrv_filename(bs, bs->filename, sizeof(bs->filename));
+    bdrv_refresh_filename(bs);
 
     /* For snapshot=on, create a temporary qcow2 overlay. bs points to the
      * temporary snapshot afterwards. */
@@ -1822,8 +1823,10 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
             if (local_err != NULL) {
                 error_propagate(errp, local_err);
             } else {
+                char filename[PATH_MAX];
+                bdrv_filename(reopen_state->bs, filename, sizeof(filename));
                 error_setg(errp, "failed while preparing to reopen image '%s'",
-                           reopen_state->bs->filename);
+                           filename);
             }
             goto error;
         }
@@ -2440,6 +2443,7 @@ int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
     BlockDriverState *base_bs = NULL;
     BlockDriverState *new_top_bs = NULL;
     BlkIntermediateStates *intermediate_state, *next;
+    char base_filename[PATH_MAX];
     int ret = -EIO;
 
     QSIMPLEQ_HEAD(states_to_delete, BlkIntermediateStates) states_to_delete;
@@ -2486,7 +2490,10 @@ int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
     }
 
     /* success - we can delete the intermediate states, and link top->base */
-    backing_file_str = backing_file_str ? backing_file_str : base_bs->filename;
+    if (!backing_file_str) {
+        bdrv_filename(base_bs, base_filename, sizeof(base_filename));
+        backing_file_str = base_filename;
+    }
     ret = bdrv_change_backing_file(new_top_bs, backing_file_str,
                                    base_bs->drv ? base_bs->drv->format_name : "");
     if (ret) {
@@ -2992,8 +2999,7 @@ char *bdrv_get_encrypted_filename(BlockDriverState *bs, char *dest, size_t sz)
         pstrcpy(dest, sz, bs->backing_file);
         return dest;
     } else if (bs->encrypted) {
-        pstrcpy(dest, sz, bs->filename);
-        return dest;
+        return bdrv_filename(bs, dest, sz);
     } else {
         dest[0] = '\0';
         return NULL;
@@ -3094,7 +3100,7 @@ int bdrv_is_snapshot(BlockDriverState *bs)
 }
 
 /* backing_file can either be relative, or absolute, or a protocol.  If it is
- * relative, it must be relative to the chain.  So, passing in bs->filename
+ * relative, it must be relative to the chain.  So, passing in the filename
  * from a BDS as backing_file should not be done, as that may be relative to
  * the CWD rather than the chain. */
 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
@@ -3127,10 +3133,12 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
                 break;
             }
         } else {
+            char curr_filename[PATH_MAX];
+
             /* If not an absolute filename path, make it relative to the current
              * image's filename path */
-            path_combine(filename_tmp, PATH_MAX, curr_bs->filename,
-                         backing_file);
+            bdrv_filename(curr_bs, curr_filename, sizeof(curr_filename));
+            path_combine(filename_tmp, PATH_MAX, curr_filename, backing_file);
 
             /* We are going to compare absolute pathnames */
             if (!realpath(filename_tmp, filename_full)) {
@@ -3139,7 +3147,7 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
 
             /* We need to make sure the backing filename we are comparing against
              * is relative to the current image filename (or absolute) */
-            path_combine(filename_tmp, PATH_MAX, curr_bs->filename,
+            path_combine(filename_tmp, PATH_MAX, curr_filename,
                          curr_bs->backing_file);
 
             if (!realpath(filename_tmp, backing_file_full)) {
diff --git a/block/blkverify.c b/block/blkverify.c
index cb9ce02..d277e63 100644
--- a/block/blkverify.c
+++ b/block/blkverify.c
@@ -309,8 +309,7 @@ static void blkverify_refresh_filename(BlockDriverState *bs)
     BDRVBlkverifyState *s = bs->opaque;
 
     /* bs->file has already been refreshed */
-    bdrv_filename(s->test_file, s->test_file->filename,
-                  sizeof(s->test_file->filename));
+    bdrv_refresh_filename(s->test_file);
 
     if (bs->file->full_open_options && s->test_file->full_open_options) {
         QDict *opts = qdict_new();
diff --git a/block/commit.c b/block/commit.c
index 7312a5b..6d387df 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -227,7 +227,9 @@ void commit_start(BlockDriverState *bs, BlockDriverState *base,
     overlay_bs = bdrv_find_overlay(bs, top);
 
     if (overlay_bs == NULL) {
-        error_setg(errp, "Could not find overlay image for %s:", top->filename);
+        char top_filename[PATH_MAX];
+        bdrv_filename(top, top_filename, sizeof(top_filename));
+        error_setg(errp, "Could not find overlay image for %s:", top_filename);
         return;
     }
 
diff --git a/block/mirror.c b/block/mirror.c
index fc4d8f5..61fac1d 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -781,25 +781,31 @@ void commit_active_start(BlockDriverState *bs, BlockDriverState *base,
 
     length = bdrv_getlength(bs);
     if (length < 0) {
-        error_setg_errno(errp, -length,
-                         "Unable to determine length of %s", bs->filename);
+        char filename[PATH_MAX];
+        error_setg_errno(errp, -length, "Unable to determine length of %s",
+                         bdrv_filename(bs, filename, sizeof(filename)));
         goto error_restore_flags;
     }
 
     base_length = bdrv_getlength(base);
     if (base_length < 0) {
+        char base_filename[PATH_MAX];
+        bdrv_filename(base, base_filename, sizeof(base_filename));
         error_setg_errno(errp, -base_length,
-                         "Unable to determine length of %s", base->filename);
+                         "Unable to determine length of %s", base_filename);
         goto error_restore_flags;
     }
 
     if (length > base_length) {
         ret = bdrv_truncate(base, length);
         if (ret < 0) {
+            char filename[PATH_MAX], base_filename[PATH_MAX];
+            bdrv_filename(bs, filename, sizeof(filename));
+            bdrv_filename(base, base_filename, sizeof(base_filename));
             error_setg_errno(errp, -ret,
                             "Top image %s is larger than base image %s, and "
                              "resize of base image failed",
-                             bs->filename, base->filename);
+                             filename, base_filename);
             goto error_restore_flags;
         }
     }
diff --git a/block/qapi.c b/block/qapi.c
index 2ce5097..dc58135 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -38,7 +38,8 @@ BlockDeviceInfo *bdrv_block_device_info(BlockDriverState *bs, Error **errp)
     BlockDriverState *bs0;
     BlockDeviceInfo *info = g_malloc0(sizeof(*info));
 
-    info->file                   = g_strdup(bs->filename);
+    info->file                   = bdrv_filename(bs, g_malloc(PATH_MAX),
+                                                 PATH_MAX);
     info->ro                     = bs->read_only;
     info->drv                    = g_strdup(bs->drv->format_name);
     info->encrypted              = bs->encrypted;
@@ -218,7 +219,7 @@ void bdrv_query_image_info(BlockDriverState *bs,
     }
 
     info = g_new0(ImageInfo, 1);
-    info->filename        = g_strdup(bs->filename);
+    info->filename        = bdrv_filename(bs, g_malloc(PATH_MAX), PATH_MAX);
     info->format          = g_strdup(bdrv_get_format_name(bs));
     info->virtual_size    = size;
     info->actual_size     = bdrv_get_allocated_file_size(bs);
diff --git a/block/quorum.c b/block/quorum.c
index 00d1fb0..2f6c45f 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1003,7 +1003,7 @@ static void quorum_refresh_filename(BlockDriverState *bs)
     int i;
 
     for (i = 0; i < s->num_children; i++) {
-        bdrv_filename(s->bs[i], s->bs[i]->filename, sizeof(s->bs[i]->filename));
+        bdrv_refresh_filename(s->bs[i]);
         if (!s->bs[i]->full_open_options) {
             return;
         }
diff --git a/block/raw-posix.c b/block/raw-posix.c
index b61c11f..ef56915 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -512,12 +512,14 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
         goto fail;
     }
     if (!s->use_aio && (bdrv_flags & BDRV_O_NATIVE_AIO)) {
+        char filename[PATH_MAX];
+        bdrv_filename(bs, filename, sizeof(filename));
         error_printf("WARNING: aio=native was specified for '%s', but "
                      "it requires cache.direct=on, which was not "
                      "specified. Falling back to aio=threads.\n"
                      "         This will become an error condition in "
                      "future QEMU versions.\n",
-                     bs->filename);
+                     filename);
     }
 #endif
 
@@ -2095,8 +2097,10 @@ static bool hdev_is_sg(BlockDriverState *bs)
     struct stat st;
     struct sg_scsi_id scsiid;
     int sg_version;
+    char filename[PATH_MAX];
 
-    if (stat(bs->filename, &st) >= 0 && S_ISCHR(st.st_mode) &&
+    bdrv_filename(bs, filename, sizeof(filename));
+    if (stat(filename, &st) >= 0 && S_ISCHR(st.st_mode) &&
         !bdrv_ioctl(bs, SG_GET_VERSION_NUM, &sg_version) &&
         !bdrv_ioctl(bs, SG_GET_SCSI_ID, &scsiid)) {
         DPRINTF("SG device found: type=%d, version=%d\n",
diff --git a/block/raw_bsd.c b/block/raw_bsd.c
index e3d2d04..98b8a12 100644
--- a/block/raw_bsd.c
+++ b/block/raw_bsd.c
@@ -210,6 +210,8 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
     bs->sg = bs->file->sg;
 
     if (bs->probed && !bdrv_is_read_only(bs)) {
+        char filename[PATH_MAX];
+        bdrv_filename(bs->file, filename, sizeof(filename));
         fprintf(stderr,
                 "WARNING: Image format was not specified for '%s' and probing "
                 "guessed raw.\n"
@@ -217,7 +219,7 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
                 "raw images, write operations on block 0 will be restricted.\n"
                 "         Specify the 'raw' format explicitly to remove the "
                 "restrictions.\n",
-                bs->file->filename);
+                filename);
     }
 
     return 0;
diff --git a/block/vhdx-log.c b/block/vhdx-log.c
index 47fec63..1f4f57d 100644
--- a/block/vhdx-log.c
+++ b/block/vhdx-log.c
@@ -782,13 +782,16 @@ int vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s, bool *flushed,
 
     if (logs.valid) {
         if (bs->read_only) {
+            char filename[PATH_MAX];
+            bdrv_filename(bs, filename, sizeof(filename));
+
             ret = -EPERM;
             error_setg_errno(errp, EPERM,
                              "VHDX image file '%s' opened read-only, but "
                              "contains a log that needs to be replayed.  To "
                              "replay the log, execute:\n qemu-img check -r "
                              "all '%s'",
-                             bs->filename, bs->filename);
+                             filename, filename);
             goto exit;
         }
         /* now flush the log */
diff --git a/block/vmdk.c b/block/vmdk.c
index fbaab67..cdc2bb3 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -444,9 +444,11 @@ static int vmdk_init_tables(BlockDriverState *bs, VmdkExtent *extent,
                      extent->l1_table,
                      l1_size);
     if (ret < 0) {
+        char extent_filename[PATH_MAX];
+        bdrv_filename(extent->file, extent_filename, sizeof(extent_filename));
         error_setg_errno(errp, -ret,
                          "Could not read l1 table from extent '%s'",
-                         extent->file->filename);
+                         extent_filename);
         goto fail_l1;
     }
     for (i = 0; i < extent->l1_size; i++) {
@@ -464,9 +466,11 @@ static int vmdk_init_tables(BlockDriverState *bs, VmdkExtent *extent,
                          extent->l1_backup_table,
                          l1_size);
         if (ret < 0) {
+            char extent_filename[PATH_MAX];
+            bdrv_filename(extent->file, extent_filename, sizeof(extent_filename));
             error_setg_errno(errp, -ret,
                              "Could not read l1 backup table from extent '%s'",
-                             extent->file->filename);
+                             extent_filename);
             goto fail_l1b;
         }
         for (i = 0; i < extent->l1_size; i++) {
@@ -495,9 +499,10 @@ static int vmdk_open_vmfs_sparse(BlockDriverState *bs,
 
     ret = bdrv_pread(file, sizeof(magic), &header, sizeof(header));
     if (ret < 0) {
+        char filename[PATH_MAX];
         error_setg_errno(errp, -ret,
                          "Could not read header from file '%s'",
-                         file->filename);
+                         bdrv_filename(file, filename, sizeof(filename)));
         return ret;
     }
     ret = vmdk_add_extent(bs, file, false,
@@ -572,9 +577,10 @@ static int vmdk_open_vmdk4(BlockDriverState *bs,
 
     ret = bdrv_pread(file, sizeof(magic), &header, sizeof(header));
     if (ret < 0) {
+        char filename[PATH_MAX];
         error_setg_errno(errp, -ret,
                          "Could not read header from file '%s'",
-                         file->filename);
+                         bdrv_filename(file, filename, sizeof(filename)));
         return -EINVAL;
     }
     if (header.capacity == 0) {
@@ -818,8 +824,10 @@ static int vmdk_parse_extents(const char *desc, BlockDriverState *bs,
         if (!path_is_absolute(fname) && !path_has_protocol(fname) &&
             !desc_file_path[0])
         {
+            char filename[PATH_MAX];
+            bdrv_filename(bs->file, filename, sizeof(filename));
             error_setg(errp, "Cannot use relative extent paths with VMDK "
-                       "descriptor file '%s'", bs->file->filename);
+                       "descriptor file '%s'", filename);
             return -EINVAL;
         }
 
@@ -2086,7 +2094,8 @@ static ImageInfo *vmdk_get_extent_info(VmdkExtent *extent)
     ImageInfo *info = g_new0(ImageInfo, 1);
 
     *info = (ImageInfo){
-        .filename         = g_strdup(extent->file->filename),
+        .filename         = bdrv_filename(extent->file, g_malloc(PATH_MAX),
+                                          PATH_MAX),
         .format           = g_strdup(extent->type),
         .virtual_size     = extent->sectors * BDRV_SECTOR_SIZE,
         .compressed       = extent->compressed,
diff --git a/block/vpc.c b/block/vpc.c
index 3e385d9..581c997 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -204,9 +204,11 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
 
     checksum = be32_to_cpu(footer->checksum);
     footer->checksum = 0;
-    if (vpc_checksum(s->footer_buf, HEADER_SIZE) != checksum)
+    if (vpc_checksum(s->footer_buf, HEADER_SIZE) != checksum) {
+        char filename[PATH_MAX];
         fprintf(stderr, "block-vpc: The header checksum of '%s' is "
-            "incorrect.\n", bs->filename);
+                "incorrect.\n", bdrv_filename(bs, filename, sizeof(filename)));
+    }
 
     /* Write 'checksum' back to footer, or else will leave it with zero. */
     footer->checksum = cpu_to_be32(checksum);
diff --git a/blockdev.c b/blockdev.c
index 62a4586..21befcf 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -227,9 +227,11 @@ bool drive_check_orphaned(void)
         /* Unless this is a default drive, this may be an oversight. */
         if (!blk_get_attached_dev(blk) && !dinfo->is_default &&
             dinfo->type != IF_NONE) {
+            char filename[PATH_MAX];
+            bdrv_filename(blk_bs(blk), filename, sizeof(filename));
             fprintf(stderr, "Warning: Orphaned drive without device: "
                     "id=%s,file=%s,if=%s,bus=%d,unit=%d\n",
-                    blk_name(blk), blk_bs(blk)->filename, if_name[dinfo->type],
+                    blk_name(blk), filename, if_name[dinfo->type],
                     dinfo->bus, dinfo->unit);
             rs = true;
         }
@@ -1507,8 +1509,10 @@ static void external_snapshot_prepare(BlkTransactionState *common,
 
     /* create new image w/backing file */
     if (mode != NEW_IMAGE_MODE_EXISTING) {
+        char old_filename[PATH_MAX];
+        bdrv_filename(state->old_bs, old_filename, sizeof(old_filename));
         bdrv_img_create(new_image_file, format,
-                        state->old_bs->filename,
+                        old_filename,
                         state->old_bs->drv->format_name,
                         NULL, -1, flags, &local_err, false);
         if (local_err) {
@@ -2388,7 +2392,9 @@ void qmp_block_commit(const char *device,
     top_bs = bs;
 
     if (has_top && top) {
-        if (strcmp(bs->filename, top) != 0) {
+        char filename[PATH_MAX];
+        bdrv_filename(bs, filename, sizeof(filename));
+        if (strcmp(filename, top) != 0) {
             top_bs = bdrv_find_backing_image(bs, top);
         }
     }
@@ -2536,7 +2542,9 @@ void qmp_drive_backup(const char *device, const char *target,
     if (mode != NEW_IMAGE_MODE_EXISTING) {
         assert(format && drv);
         if (source) {
-            bdrv_img_create(target, format, source->filename,
+            char source_filename[PATH_MAX];
+            bdrv_filename(source, source_filename, sizeof(source_filename));
+            bdrv_img_create(target, format, source_filename,
                             source->drv->format_name, NULL,
                             size, flags, &local_err, false);
         } else {
@@ -2781,13 +2789,16 @@ void qmp_drive_mirror(const char *device, const char *target,
         bdrv_img_create(target, format,
                         NULL, NULL, NULL, size, flags, &local_err, false);
     } else {
+        char source_filename[PATH_MAX];
+
         switch (mode) {
         case NEW_IMAGE_MODE_EXISTING:
             break;
         case NEW_IMAGE_MODE_ABSOLUTE_PATHS:
             /* create new image with backing file */
+            bdrv_filename(source, source_filename, sizeof(source_filename));
             bdrv_img_create(target, format,
-                            source->filename,
+                            source_filename,
                             source->drv->format_name,
                             NULL, size, flags, &local_err, false);
             break;
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 14ad4c3..677c05a 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -370,7 +370,6 @@ struct BlockDriverState {
      * regarding this BDS's context */
     QLIST_HEAD(, BdrvAioNotifier) aio_notifiers;
 
-    char filename[PATH_MAX];
     char backing_file[PATH_MAX]; /* if non zero, the image is a diff of
                                     this file image */
     char backing_format[16]; /* if non-zero and backing_file exists */
-- 
2.4.6

[Qemu-devel] [PATCH v2 5/5] iotests: Test changed Quorum filename

[Max Reitz]

After drive-mirror replacing a Quorum child, the filename of the Quorum
BDS should reflect the change. This patch replaces the existing test for
whether the operation did actually exchange the BDS (which simply tested
whether the new BDS existed) by a test which examines the children list
contained in the Quorum BDS's filename as returned by query-block.

As a nice side effect of confirming that the new BDS actually belongs to
the Quorum BDS, this checks whether the filename was properly updated.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 tests/qemu-iotests/041 | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
index 3d46ed7..316f42a 100755
--- a/tests/qemu-iotests/041
+++ b/tests/qemu-iotests/041
@@ -18,6 +18,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
+import json
 import time
 import os
 import iotests
@@ -908,10 +909,18 @@ class TestRepairQuorum(iotests.QMPTestCase):
         self.assert_qmp(result, 'return', {})
 
         self.complete_and_wait(drive="quorum0")
-        result = self.vm.qmp('query-named-block-nodes')
-        self.assert_qmp(result, 'return[0]/file', quorum_repair_img)
-        # TODO: a better test requiring some QEMU infrastructure will be added
-        #       to check that this file is really driven by quorum
+
+        result = self.vm.qmp('query-block')
+        for blockdev in result['return']:
+            if blockdev['device'] == 'quorum0':
+                filename = blockdev['inserted']['image']['filename']
+                self.assertEquals(filename[:5], 'json:')
+                children = json.loads(filename[5:])['children']
+                self.assertEquals(children[0]['file']['filename'], quorum_img1)
+                self.assertEquals(children[1]['file']['filename'],
+                                  quorum_repair_img)
+                self.assertEquals(children[2]['file']['filename'], quorum_img3)
+
         self.vm.shutdown()
 
 if __name__ == '__main__':
-- 
2.4.6

Re: [Qemu-devel] [Qemu-block] [PATCH v2 0/5] block: Drop BDS.filename

[Stefan Hajnoczi]

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On Wed, Aug 05, 2015 at 10:52:44PM +0200, Max Reitz wrote:
> Regarding the fear that this might change current behavior, especially
> for libvirt which used filenames to identify nodes in the BDS graph:
> Since bdrv_open() already calls bdrv_refresh_filename() today, and
> apparently everything works fine, this series will most likely not break
> anything. The only thing that will change is if the BDS graph is
> dynamically reconfigured at runtime, and in that case it's most likely a
> bug fix. Also, I don't think libvirt supports such cases already.

I haven't reviewed the patches but seems like a perfectly reasonable
thing to do at the beginning of the QEMU 2.5 development cycle.  If
anything comes up there will be time ot fix it before the next QEMU
version is released.

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