Bit shifting can be fun, but in this case it was unnecessary. The
upper 44 bits of the 64-bit BAT entry is specifies the File Offset,
so we shifted the bits to get access to the value.
However, per the spec the value is in MB. So we dutifully shifted back
to the left by 20 bits, to convert to a true uint64_t file offset.
This replaces those steps with just a bit mask, to get rid of the lower
20 bits instead.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This adds support for writing to VHDX image files, using coroutines.
Writes into the BAT table goes through the VHDX log. Currently, BAT
table writes occur when expanding a dynamic VHDX file, and allocating a
new BAT entry.
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>
Regions in the image file cannot overlap - the log, region tables,
and metdata must all be unique and non-overlapping.
This adds region checking by means of a QLIST; there can be a variable
number of regions and metadata (there may be metadata or region tables
that we do not recognize / know about, but are not required).
This adds the capability to register a region for later checking, and
to check against registered regions for any overlap.
Also, if neither the BAT or Metadata region tables are found, return
error.
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>
Allow tracking of first file write in the VHDX image, as well as
the ability to update the GUID in the header. This is in preparation
for log support.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This moves the endian translation functions out from the vhdx.c source,
into a separate source file. In addition to the previously defined
endian functions, new endian translation functions for log support are
added as well.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This adds some magic number defines, and internal structure definitions
for VHDX log replay support. The struct VHDXLogEntries does not reflect
an on-disk data structure, and thus does not need to be packed.
Some minor code style fixes are applied as well.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
In preparation for VHDX log support, move these structures to the
header.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This adds the ability to update the headers in a VHDX image, including
generating a new MS-compatible GUID.
As VHDX depends on uuid.h, VHDX is now a configurable build option. If
VHDX support is enabled, that will also enable uuid as well. The
default is to have VHDX enabled.
To enable/disable VHDX: --enable-vhdx, --disable-vhdx
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Just a couple of minor comments to help note where allocated
buffers are freed, and a typo fix.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
All these typos were found by codespell.
sould -> should
emperical -> empirical
intialization -> initialization
successfuly -> successfully
gaurantee -> guarantee
Fix also another error (before before) in the same context.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
This is the initial block driver framework for VHDX image support
(i.e. Hyper-V image file formats), that supports opening VHDX files, and
parsing the headers.
This commit does not yet enable:
- reading
- writing
- updating the header
- differencing files (images with parents)
- log replay / dirty logs (only clean images)
This is based on Microsoft's VHDX specification:
"VHDX Format Specification v0.95", published 4/12/2012
https://www.microsoft.com/en-us/download/details.aspx?id=29681
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This is based on Microsoft's VHDX specification:
"VHDX Format Specification v0.95", published 4/12/2012
https://www.microsoft.com/en-us/download/details.aspx?id=29681
These structures define the various header, metadata, and other
block structures defined in the VHDX specification.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
