Am Thu, 21 Dec 2017 13:51:40 -0500 schrieb Chris Mason: > On 12/20/2017 03:59 PM, Timofey Titovets wrote: >> How reproduce: >> touch test_file >> chattr +C test_file >> dd if=/dev/zero of=test_file bs=1M count=1 >> btrfs fi def -vrczlib test_file >> filefrag -v test_file >> >> test_file >> Filesystem type is: 9123683e >> File size of test_file is 1048576 (256 blocks of 4096 bytes) >> ext: logical_offset: physical_offset: length: expected: flags: >> 0: 0.. 31: 72917050.. 72917081: 32: encoded >> 1: 32.. 63: 72917118.. 72917149: 32: 72917082: encoded >> 2: 64.. 95: 72919494.. 72919525: 32: 72917150: encoded >> 3: 96.. 127: 72927576.. 72927607: 32: 72919526: encoded >> 4: 128.. 159: 72943261.. 72943292: 32: 72927608: encoded >> 5: 160.. 191: 72944929.. 72944960: 32: 72943293: encoded >> 6: 192.. 223: 72944952.. 72944983: 32: 72944961: encoded >> 7: 224.. 255: 72967084.. 72967115: 32: 72944984: >> last,encoded,eof >> test_file: 8 extents found >> >> I can't found at now, where that error happen in code, >> but it's reproducible on Linux 4.14.8 > > We'll silently cow in a few cases, this is one. I think the question was about compression, not cow. I can reproduce this behavior: $ touch nocow.dat $ touch cow.dat $ chattr +c cow.dat $ chattr +C nocow.dat $ dd if=/dev/zero of=cow.dat count=1 bs=1M $ dd if=/dev/zero of=nocow.dat count=1 bs=1M $ filefrag -v cow.dat Filesystem type is: 9123683e File size of cow.dat is 1048576 (256 blocks of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 31: 1044845154..1044845185: 32: encoded,shared 1: 32.. 63: 1044845166..1044845197: 32: 1044845186: encoded,shared 2: 64.. 95: 1044845167..1044845198: 32: 1044845198: encoded,shared 3: 96.. 127: 1044851064..1044851095: 32: 1044845199: encoded,shared 4: 128.. 159: 1044851065..1044851096: 32: 1044851096: encoded,shared 5: 160.. 191: 1044852160..1044852191: 32: 1044851097: encoded,shared 6: 192.. 223: 1044943106..1044943137: 32: 1044852192: encoded,shared 7: 224.. 255: 1045054792..1045054823: 32: 1044943138: last,encoded,shared,eof cow.dat: 8 extents found $ filefrag -v nocow.dat Filesystem type is: 9123683e File size of nocow.dat is 1048576 (256 blocks of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 255: 1196077983..1196078238: 256: last,shared,eof nocow.dat: 1 extent found Now it seems to be compressed (8x 128k extents): $ filefrag -v nocow.dat Filesystem type is: 9123683e File size of nocow.dat is 1048576 (256 blocks of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 31: 1121866367..1121866398: 32: encoded,shared 1: 32.. 63: 1121866369..1121866400: 32: 1121866399: encoded,shared 2: 64.. 95: 1121866370..1121866401: 32: 1121866401: encoded,shared 3: 96.. 127: 1121866371..1121866402: 32: 1121866402: encoded,shared 4: 128.. 159: 1121866372..1121866403: 32: 1121866403: encoded,shared 5: 160.. 191: 1121866373..1121866404: 32: 1121866404: encoded,shared 6: 192.. 223: 1121866374..1121866405: 32: 1121866405: encoded,shared 7: 224.. 255: 1121866375..1121866406: 32: 1121866406: last,encoded,shared,eof nocow.dat: 8 extents found -- Regards, Kai Replies to list-only preferred. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
