On 07/27/2011 08:43 AM, Michael Tokarev wrote:
Index: qemu/block.c =================================================================== --- qemu.orig/block.c +++ qemu/block.c @@ -651,6 +651,34 @@ unlink_and_fail: return ret; }+int bdrv_reopen(BlockDriverState *bs, int bdrv_flags) +{ + BlockDriver *drv = bs->drv; + int ret = 0, open_flags; + + /* Quiesce IO for the given block device */ + qemu_aio_flush(); + if (bdrv_flush(bs)) { + qerror_report(QERR_DATA_SYNC_FAILED, bs->device_name); + return ret; + } + open_flags = bs->open_flags; + bdrv_close(bs); + + ret = bdrv_open(bs, bs->filename, bdrv_flags, drv); + if (ret< 0) { + /* Reopen failed. Try to open with original flags */ + qerror_report(QERR_REOPEN_FILE_FAILED, bs->filename); + ret = bdrv_open(bs, bs->filename, open_flags, drv); + if (ret< 0) { + /* Reopen failed with orig and modified flags */ + abort(); + }Can we please avoid this stuff completely? Just keep the old device open still, until you're sure new one is ok.
I may be misremembering, but I thought Christoph had mentioned wanting to write a kernel patch to toggle O_DIRECT through fcntl().
This seems like the only way to make this not racy to me. Regards, Anthony Liguori
