On 12/16/2016 02:11 PM, Chandan Rajendra wrote:
On Thursday, December 15, 2016 05:03:30 PM Qu Wenruo wrote:
Although commit 9c4b820412746b3 tried to make the rollback condition
less restrict, to co-operate with new rollback behavior, it's still too
restrict.
If btrfs allocates a new data chunk, it's highly possible that the new
chunk will not be 1:1 mapped anymore.
And this makes old rollback check fails, and refuse to rollback.
This patch rework it by checking rollback condition more accurately.
1) Rollback condition
Unlike old chunk level check, we use file extent level check.
So we manually check every file extents of convert image file.
Only when all file extents except ones in btrfs relocated ranges(*)
are mapped 1:1 we allow rollback.
This behavior make both old and new behavior happy.
*:
[0, 1M)
[btrfs_sb_offset(1), +64K)
[btrfs_sb_offset(2), +64K)
2) Rollback method
Old rollback method is quite complex, using extent_io tree to mark
every checked ranges.
And do extra chunk tree operation before rollback.
The new rollback method is quite simple.
1) open btrfs
2) read and save relocated data
3) close btrfs
4) write relocated into place.
Such rework fixes the following problem
1) rollback failure after new data chunk allocation
2) rollback failure after correct NO_HOLES convert
Hi Qu,
With this patch applied, I get the following on an x86_64 machine,
[root@localhost]~/btrfs-progs# btrfs-convert -r /dev/loop0
ctree.c:1112: btrfs_search_slot: Warning: assertion `p->nodes[0] != NULL` failed, value 1
btrfs-convert(btrfs_search_slot+0x117)[0x40c906]
btrfs-convert(btrfs_lookup_dir_item+0x70)[0x41d902]
btrfs-convert(main+0x5e2)[0x43af50]
/lib64/libc.so.6(__libc_start_main+0xf0)[0x7f7fb6168700]
btrfs-convert(_start+0x29)[0x408a69]
extent buffer leak: start 67305472 len 16384
rollback complete
Thanks for the report.
That's caused by my last time v2 update of the 2nd patch.
Which forgot to release the path before searching for rootid.
I'll update the patch soon.
Thanks,
Qu
The same error occurs on a ppc64 machine when using 64k sectorsize.
The three 'rollback' patches were applied on top of commit
9ce512ac57cb08edf2f742da085c383834f804dd (i.e. btrfs-progs: check: Fix false
alert on generation mismatch for tree reloc tree) that is available on David's
devel branch.
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