bwlp/qemu.git/block/cow.c, branch spice_video_codecs

block: delete cow block driver

2014-09-22T10:39:45+00:00

This patch removes support for the cow file format. Normally we do not break backwards compatibility but in this case there is no impact and it is the most logical option. Extraordinary claims require extraordinary evidence so I will show why removing the cow block driver is the right thing to do. The cow file format is the disk image format for Usermode Linux, a way of running a Linux system in userspace. The performance of UML was never great and it was hacky, but it enjoyed some popularity before hardware virtualization support became mainstream. QEMU's block/cow.c is supposed to read this image file format. Unfortunately the file format was underspecified: 1. Earlier Linux versions used the MAXPATHLEN constant for the backing filename field. The value of MAXPATHLEN can change, so Linux switched to a 4096 literal but QEMU has a 1024 literal. 2. Padding was not used on the header struct (both in the Linux kernel and in QEMU) so the struct layout varied across architectures. In particular, i386 and x86_64 were different due to int64_t alignment differences. Linux now uses __attribute__((packed)), QEMU does not. Therefore: 1. QEMU cow images do not conform to the Linux cow image file format. 2. cow images cannot be shared between different host architectures. This means QEMU cow images are useless and QEMU has not had bug reports from users actually hitting these issues. Let's get rid of this thing, it serves no purpose and no one will be affected. Signed-off-by: Stefan Hajnoczi Reviewed-by: Markus Armbruster Message-id: 1410877464-20481-1-git-send-email-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi

block: round up file size to nearest sector

2014-09-12T13:43:06+00:00

Currently the file size requested by user is rounded down to nearest sector, causing the actual file size could be a bit less than the size user requested. Since some formats (like qcow2) record virtual disk size in bytes, this can make the last few bytes cannot be accessed. This patch fixes it by rounding up file size to nearest sector so that the actual file size is no less than the requested file size. Signed-off-by: Hu Tao Reviewed-by: Kevin Wolf Reviewed-by: Eric Blake Reviewed-by: Max Reitz Signed-off-by: Kevin Wolf

block/cow: Avoid use of uninitialized cow_bs in error path

2014-07-01T08:15:34+00:00

Commit 25814e8987 introduced an error-exit code path which does a "goto exit" before the cow_bs variable is initialized, meaning we would call bdrv_unref() on an uninitialized variable and likely segfault. Fix this by moving the NULL-initialization to the top of the function and making the exit code path handle the case where it is NULL. Signed-off-by: Peter Maydell Reviewed-by: Eric Blake Signed-off-by: Stefan Hajnoczi

block: Catch backing files assigned to non-COW drivers

2014-06-26T11:51:01+00:00

Since we parse backing.* options to add a backing file from the command line when the driver didn't assign one, it has been possible to have a backing file for e.g. raw images (it just was never accessed). This is obvious nonsense and should be rejected. Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake

cleanup QEMUOptionParameter

2014-06-16T09:23:21+00:00

Now that all backend drivers are using QemuOpts, remove all QEMUOptionParameter related codes. Signed-off-by: Dong Xu Wang Signed-off-by: Chunyan Liu Signed-off-by: Stefan Hajnoczi

cow.c: replace QEMUOptionParameter with QemuOpts

2014-06-16T09:23:20+00:00

Reviewed-by: Eric Blake Reviewed-by: Stefan Hajnoczi Signed-off-by: Dong Xu Wang Signed-off-by: Chunyan Liu Signed-off-by: Stefan Hajnoczi

change block layer to support both QemuOpts and QEMUOptionParamter

2014-06-16T09:23:20+00:00

Change block layer to support both QemuOpts and QEMUOptionParameter. After this patch, it will change backend drivers one by one. At the end, QEMUOptionParameter will be removed and only QemuOpts is kept. Signed-off-by: Dong Xu Wang Signed-off-by: Chunyan Liu Reviewed-by: Eric Blake Signed-off-by: Stefan Hajnoczi

block: Use correct width in format strings

2014-04-30T12:46:17+00:00

Instead of blindly relying on a normal integer having a width of 32 bits (which is a pretty good assumption, but we should not rely on it if there is no need), use the correct format string macros. This does not touch DEBUG output. Signed-off-by: Max Reitz Signed-off-by: Kevin Wolf

block: do not abuse EMEDIUMTYPE

2014-02-21T20:02:24+00:00

Returning "Wrong medium type" for an image that does not have a valid header is a bit weird. Improve the error by mentioning what format was trying to open it. Signed-off-by: Paolo Bonzini Reviewed-by: Fam Zheng Signed-off-by: Kevin Wolf

cow: correctly propagate errors

2014-02-21T20:02:23+00:00

Signed-off-by: Paolo Bonzini Reviewed-by: Fam Zheng Signed-off-by: Kevin Wolf