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path: root/block/cow.c
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2012-04-05block: push recursive flushing up from driversPaolo Bonzini1-6/+0
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-12-15block/cow: Return real error codeLi Zhi Hui1-15/+29
Signed-off-by: Li Zhi Hui <zhihuili@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-12-05Merge remote-tracking branch 'kwolf/for-anthony' into stagingAnthony Liguori1-24/+22
2011-12-05cow: use bdrv_co_is_allocated()Stefan Hajnoczi1-3/+3
Now that bdrv_co_is_allocated() is available we can use it instead of the synchronous bdrv_is_allocated() interface. This is a follow-up that Kevin Wolf <kwolf@redhat.com> pointed out after applying the series that introduces bdrv_co_is_allocated(). It is safe to make cow_read() a coroutine_fn because its only caller is a coroutine_fn. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-12-05cow: convert to .bdrv_co_is_allocated()Stefan Hajnoczi1-4/+4
The cow block driver does not keep internal state for cluster lookups. This means it is safe to perform cluster lookups in coroutine context without risk of race conditions that corrupt internal state. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-12-05block: Use bdrv functions to replace file operation in cow.cLi Zhi Hui1-18/+16
Since common file operation functions lack of error detection, so change them to bdrv series functions. Signed-off-by: Li Zhi Hui <zhihuili@linux.vnet.ibm.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-12-02fix spelling in block sub directoryDong Xu Wang1-1/+1
Cc: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2011-11-11block: Rename bdrv_co_flush to bdrv_co_flush_to_diskKevin Wolf1-10/+12
There are two different types of flush that you can do: Flushing one level up to the OS (i.e. writing data to the host page cache) or flushing it all the way down to the disk. The existing functions flush to the disk, reflect this in the function name. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-10-21block: change flush to co_flushPaolo Bonzini1-3/+3
Since coroutine operation is now mandatory, convert all bdrv_flush implementations to coroutines. For qcow2, this means taking the lock. Other implementations are simpler and just forward bdrv_flush to the underlying protocol, so they can avoid the lock. The bdrv_flush callback is then unused and can be eliminated. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-10-21block: take lock around bdrv_write implementationsPaolo Bonzini1-1/+12
This does the first part of the conversion to coroutines, by wrapping bdrv_write implementations to take the mutex. Drivers that implement bdrv_write rather than bdrv_co_writev can then benefit from asynchronous operation (at least if the underlying protocol supports it, which is not the case for raw-win32), even though they still operate with a bounce buffer. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-10-21block: take lock around bdrv_read implementationsPaolo Bonzini1-1/+12
This does the first part of the conversion to coroutines, by wrapping bdrv_read implementations to take the mutex. Drivers that implement bdrv_read rather than bdrv_co_readv can then benefit from asynchronous operation (at least if the underlying protocol supports it, which is not the case for raw-win32), even though they still operate with a bounce buffer. raw-win32 does not need the lock, because it cannot yield. nbd also doesn't probably, but better be safe. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-10-21block: add a CoMutex to synchronous read driversPaolo Bonzini1-0/+2
The big conversion of bdrv_read/write to coroutines caused the two homonymous callbacks in BlockDriver to become reentrant. It goes like this: 1) bdrv_read is now called in a coroutine, and calls bdrv_read or bdrv_pread. 2) the nested bdrv_read goes through the fast path in bdrv_rw_co_entry; 3) in the common case when the protocol is file, bdrv_co_do_readv calls bdrv_co_readv_em (and from here goes to bdrv_co_io_em), which yields until the AIO operation is complete; 4) if bdrv_read had been called from a bottom half, the main loop is free to iterate again: a device model or another bottom half can then come and call bdrv_read again. This applies to all four of read/write/flush/discard. It would also apply to is_allocated, but it is not used from within coroutines: besides qemu-img.c and qemu-io.c, which operate synchronously, the only user is the monitor. Copy-on-read will introduce a use in the block layer, and will require converting it. The solution is "simply" to convert all drivers to coroutines! We just need to add a CoMutex that is taken around affected operations. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-11-04block: Allow bdrv_flush to return errorsKevin Wolf1-2/+2
This changes bdrv_flush to return 0 on success and -errno in case of failure. It's a requirement for implementing proper error handle in users of bdrv_flush. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2010-06-22cow: Use bdrv_(p)write_sync for metadata writesKevin Wolf1-9/+11
Use bdrv_(p)write_sync to ensure metadata integrity in case of a crash. While at it, correct the wrong usage of errno. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-06-15cow: use qemu block APIChristoph Hellwig1-26/+13
Use bdrv_pwrite to access the backing device instead of pread, and convert the driver to implementing the bdrv_open method which gives it an already opened BlockDriverState for the underlying device. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-06-15cow: stop using mmapChristoph Hellwig1-37/+61
We don't have an equivalent to mmap in the qemu block API, so read and write the bitmap directly. At least in the dumb implementation added in this patch this is a lot less efficient, but it means cow can also work on windows, and over nbd or curl. And it fixes qemu-iotests testcase 012 which did not work properly due to issues with read-only mmap access. In addition we can also get rid of the now unused get_mmap_addr function. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-06-15cow: use pread/pwriteChristoph Hellwig1-5/+5
Use pread/pwrite instead of lseek + read/write in preparation of using the qemu block API. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-05-03block: Open the underlying image file in generic codeKevin Wolf1-1/+1
Format drivers shouldn't need to bother with things like file names, but rather just get an open BlockDriverState for the underlying protocol. This patch introduces this behaviour for bdrv_open implementation. For protocols which need to access the filename to open their file/device/connection/... a new callback bdrv_file_open is introduced which doesn't get an underlying file opened. For now, also some of the more obscure formats use bdrv_file_open because they open() the file themselves instead of using the block.c functions. They need to be fixed in later patches. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-03-09cow: return errno instead of -1Juan Quintela1-3/+2
Remove not needed ret = 0 assignment. Signed-off-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2010-01-26block/cow.c: fix warnings with _FORTIFY_SOURCEKirill A. Shutemov1-3/+16
CC block/cow.o cc1: warnings being treated as errors block/cow.c: In function 'cow_create': block/cow.c:251: error: ignoring return value of 'write', declared with attribute warn_unused_result block/cow.c:253: error: ignoring return value of 'ftruncate', declared with attribute warn_unused_result make: *** [block/cow.o] Error 1 Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-09-11block: use fdatasync instead of fsync if possibleChristoph Hellwig1-1/+1
If we are flushing the caches for our image files we only care about the data (including the metadata required for accessing it) but not things like timestamp updates. So try to use fdatasync instead of fsync to implement the flush operations. Unfortunately many operating systems still do not support fdatasync, so we add a qemu_fdatasync wrapper that uses fdatasync if available as per the _POSIX_SYNCHRONIZED_IO feature macro or fsync otherwise. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-06-06qemu-img: Print available options with -o ?Kevin Wolf1-2/+10
This patch adds a small help text to each of the options in the block drivers which can be displayed by using qemu-img create -f fmt -o ? Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2009-05-22Convert all block drivers to new bdrv_createKevin Wolf1-5/+21
Now we can make use of the newly introduced option structures. Instead of having bdrv_create carry more and more parameters (which are format specific in most cases), just pass a option structure as defined by the driver itself. bdrv_create2() contains an emulation of the old interface to simplify the transition. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-05-14Move block drivers into their own directoryAnthony Liguori1-0/+275
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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