This patch contains several changes for endian conversion fixes for
VHDX, particularly for big-endian machines (multibyte values in VHDX are
all on disk in LE format).
Tests were done with existing qemu-iotests on an IBM POWER7 (8406-71Y).
This includes sample images created by Hyper-V, both with dirty logs and
without.
In addition, VHDX image files created (and written to) on a BE machine
were tested on a LE machine, and vice-versa.
Reported-by: Markus Armburster <armbru@redhat.com>
Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This add an error check for an invalid descriptor entry signature,
when flushing the log descriptor entries.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Errors are inadvertently ignored in a few places. Has always been
broken. Spotted by Coverity.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
If there is a dirty log file to be replayed in a VHDX image, it is
replayed in .vhdx_open(). However, if the file is opened read-only,
then a somewhat cryptic error message results.
This adds a more helpful error message for the user. If an image file
contains a log to be replayed, and is opened read-only, the user is
instructed to run 'qemu-img check -r all' on the image file.
Running qemu-img check -r all will cause the image file to be opened
r/w, which will replay the log file. If a log file replay is detected,
this is flagged, and bdrv_check will increase the corruptions_fixed
count for the image.
[Fixed typo in error message that was pointed out by Eric Blake
<eblake@redhat.com>.
--Stefan]
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This adds support for writing to the VHDX log.
For spec details, see VHDX Specification Format v1.00:
https://www.microsoft.com/en-us/download/details.aspx?id=34750
There are a few limitations to this log support:
1.) There is no caching yet
2.) The log is flushed after each entry
The primary write interface, vhdx_log_write_and_flush(), performs a log
write followed by an immediate flush of the log.
As each log entry sector is a minimum of 4KB, partial sector writes are
filled in with data from the disk write destination.
If the current file log GUID is 0, a new GUID is generated and updated
in the header.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This adds support for VHDX v0 logs, as specified in Microsoft's
VHDX Specification Format v1.00:
https://www.microsoft.com/en-us/download/details.aspx?id=34750
The following support is added:
* Log parsing, and validation - validate that an existing log
is correct.
* Log search - search through an existing log, to find any valid
sequence of entries.
* Log replay and flush - replay an existing log, and flush/clear
the log when complete.
The VHDX log is a circular buffer, with elements (sectors) of 4KB.
A log entry is a variably-length number of sectors, that is
comprised of a header and 'descriptors', that describe each sector.
A log may contain multiple entries, know as a log sequence. In a log
sequence, each log entry immediately follows the previous entry, with an
incrementing sequence number. There can only ever be one active and
valid sequence in the log.
Each log entry must match the file log GUID in order to be valid (along
with other criteria). Once we have flushed all valid log entries, we
marked the file log GUID to be zero, which indicates a buffer with no
valid entries.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
