[Qemu-devel] [PATCH] block: return EPERM on writes or discards to read-only devices

[Qemu-devel] [PATCH] block: return EPERM on writes or discards to read-only devices

[Paolo Bonzini]

This is the behavior in the operating system, for example Linux's
blkdev_write_iter has the following:

        if (bdev_read_only(I_BDEV(bd_inode)))
                return -EPERM;

This does not apply to opening a device for read/write, when the
device only supports read-only operation.  In this case any of
EACCES, EPERM or EROFS is acceptable depending on why writing is
not possible.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/io.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/io.c b/block/io.c
index 1ce62c4..a05ad67 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1205,7 +1205,7 @@ static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs,
         return -ENOMEDIUM;
     }
     if (bs->read_only) {
-        return -EACCES;
+        return -EPERM;
     }
 
     ret = bdrv_check_byte_request(bs, offset, bytes);
@@ -2340,7 +2340,7 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
     if (ret < 0) {
         return ret;
     } else if (bs->read_only) {
-        return -EROFS;
+        return -EPERM;
     }
 
     bdrv_reset_dirty(bs, sector_num, nb_sectors);
-- 
2.3.5

Re: [Qemu-devel] [PATCH] block: return EPERM on writes or discards to read-only devices

[Stefan Hajnoczi]

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On Thu, May 07, 2015 at 05:45:48PM +0200, Paolo Bonzini wrote:
> This is the behavior in the operating system, for example Linux's
> blkdev_write_iter has the following:
> 
>         if (bdev_read_only(I_BDEV(bd_inode)))
>                 return -EPERM;
> 
> This does not apply to opening a device for read/write, when the
> device only supports read-only operation.  In this case any of
> EACCES, EPERM or EROFS is acceptable depending on why writing is
> not possible.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  block/io.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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Re: [Qemu-devel] [PATCH] block: return EPERM on writes or discards to read-only devices

[Stefan Hajnoczi]

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On Thu, May 07, 2015 at 05:45:48PM +0200, Paolo Bonzini wrote:
> This is the behavior in the operating system, for example Linux's
> blkdev_write_iter has the following:
> 
>         if (bdev_read_only(I_BDEV(bd_inode)))
>                 return -EPERM;
> 
> This does not apply to opening a device for read/write, when the
> device only supports read-only operation.  In this case any of
> EACCES, EPERM or EROFS is acceptable depending on why writing is
> not possible.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  block/io.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan

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Re: [Qemu-devel] [PATCH] block: return EPERM on writes or discards to read-only devices

[Stefan Hajnoczi]

[-- Attachment #1: Type: text/plain, Size: 719 bytes --]

On Thu, May 07, 2015 at 05:45:48PM +0200, Paolo Bonzini wrote:
> This is the behavior in the operating system, for example Linux's
> blkdev_write_iter has the following:
> 
>         if (bdev_read_only(I_BDEV(bd_inode)))
>                 return -EPERM;
> 
> This does not apply to opening a device for read/write, when the
> device only supports read-only operation.  In this case any of
> EACCES, EPERM or EROFS is acceptable depending on why writing is
> not possible.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  block/io.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan

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