-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 01/15/2014 07:00 AM, Miao Xie wrote: > When we mounted the filesystem after the crash, we got the > following message: BTRFS error (device xxx): block group 4315938816 > has wrong amount of free space BTRFS error (device xxx): failed to > load free space cache for block group 4315938816 > > It is because we didn't update the metadata of the allocated space > until the file data was written into the disk. During this time, > there was no information about the allocated spaces in either the > extent tree nor the free space cache. when we wrote out the free > space cache at this time, those spaces were lost. > > In ordered to fix this problem, I use a state tree for every block > group to record those allocated spaces. We record the information > when they are allocated, and clean up the information after the > metadata update. Besides that, we also introduce a read-write > semaphore to avoid the race between the allocation and the free > space cache write out. > > Only data block groups had this problem, so the above change is > just for data space allocation. >
I didn't like this idea at first but I've come around to it. The only thing is the data_rwsem thing, we don't need it as we are protected by the transaction being blocked when we do writeout, so nobody can data allocations during this time. Thanks, Josef -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJTFe73AAoJEANb+wAKly3BMMMP/1yY3WBGzaz5oTyNRRSgnVvl sjk7WSN2A0mhrl6lQOBlTvhgFo3gDNAtIwJaJIfWxWXZfM5i1hXSViFIc5NND3lF Jm10oaCPiTaYM0S5jqj8oeSXFyb1ny+/D4C1OfC/eRVpu9juO3bFUZYcM1XMFUcI mJxXg9Mqi1C6TOocCIdQI7ijXgm8xEPauaQy71EJZmgSjjVAXFG9BHay26L2a3Yu XIlnjyHMcgIFZXGVHQ+45S2pwWVgVZBIHLcKFSDFy4aupq/+EAN15oxdeTLBG8hJ RFJh15wLQguawlirc7boPzEugSieixbbUjn6CZqikVZke1g1fjGvrTAjiacpTDxv jskrCPYaXYWKMqGjugsVSI8GSonuWmmVRBsg4k+52U9AYM8wapjL+RHzBXU1cBqu zfyqaJhBj7EOQIu2oQDT2ZF9E+XA8dLcrysasMS+CYmcmR1Bs1fzpP2W3DoOg68F YoYuXnaAvIkvUQSsPUNGPjCn+iGCq65ZwiwnwF93RN7zlFIQt12DSn7l/NKnT/p9 1jvLkQ2MFmb6QD264mAOL5TULWyyB0AXsitIBJOMs0XWXZheLqqpv1clcaZacBFH P1yN51+d8DJmF0x0j1HacWi62WnGCh8GzR5ef5Pqi11/11xknbPugrzfFI9v1vR7 STfhGs/0sg7oQWYgarOj =Y2df -----END PGP SIGNATURE----- -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
