[Qemu-devel] [PATCH v6 00/10] block: Incremental backup series

2014-10-29 Thread Fam Zheng
v6: Rebased v4 of the series on top of qemu.git. (skipping v5 since it was used by me as a private sending, for those who received it, the code is the same :) This is the in memory part of the incremental backup feature. With the added commands, we can create a bitmap on a block backend,

Re: [Qemu-devel] [PATCH v6 00/10] block: Incremental backup series

2014-11-18 Thread Denis V. Lunev
On 18/11/14 19:08, John Snow wrote: On 11/18/2014 08:09 AM, Vladimir Sementsov-Ogievskiy wrote: (3) Data Integrity The dirty flag could work something like: - If, on first open, the file has the dirty flag set, we need to discard the bitmap data because we can no longer trust it. - If the bi

Re: [Qemu-devel] [PATCH v6 00/10] block: Incremental backup series

2014-11-18 Thread Vladimir Sementsov-Ogievskiy
(2) File Format Some standard file magic, which includes: - Some magic byte(s) - Dirty flag. Needed to tell if we can trust this data or not. - The size of the bitmap - The granularity of the bitmap - The offset to the first sector of bitmap data (Maybe? It can't hurt if we give ourselves a s

Re: [Qemu-devel] [PATCH v6 00/10] block: Incremental backup series

2014-11-18 Thread Vladimir Sementsov-Ogievskiy
(3) Data Integrity The dirty flag could work something like: - If, on first open, the file has the dirty flag set, we need to discard the bitmap data because we can no longer trust it. - If the bitmap file is clean, proceed as normal, but take a lock against any of the bitmap functions to prev

Re: [Qemu-devel] [PATCH v6 00/10] block: Incremental backup series

2014-11-18 Thread Vladimir Sementsov-Ogievskiy
Also, if we sync not the last level, bitmap.dirty_flag should be related to syncing level, not to the whole bitmap, to reduce sync overhead. Or, if we implement difficult sync policy, there should be dirty flags for each bitmap level. Despite this, only one level is needed to be saved in the bit

Re: [Qemu-devel] [PATCH v6 00/10] block: Incremental backup series

2014-11-18 Thread John Snow
On 11/18/2014 08:09 AM, Vladimir Sementsov-Ogievskiy wrote: (3) Data Integrity The dirty flag could work something like: - If, on first open, the file has the dirty flag set, we need to discard the bitmap data because we can no longer trust it. - If the bitmap file is clean, proceed as normal