On Thu, Feb 05, 2015 at 03:30:47PM -0600, Chris J Arges wrote: > On 02/05/2015 02:50 PM, Omar Sandoval wrote: > > Commit 4f579ae7de56 (ext4: fix punch hole on files with indirect > > mapping) rewrote FALLOC_FL_PUNCH_HOLE for ext4 files with indirect > > mapping. However, the case where the punch happens within one level of > > indirection is incorrect. It assumes that the partial branches returned > > from ext4_find_shared will have the same depth, but this is not > > necessarily the case even when the offsets have the same depth. For > > example, if the last block occurs at the beginning of an indirect group > > (i.e., it has an offset of 0 at the end of the offsets array), then > > ext4_find_shared will return a shallower chain. So, let's handle the > > mismatch and clean up that case. Tested with generic/270, which no > > longer leads to an inconsistent filesystem like before. > > > > Signed-off-by: Omar Sandoval <osandov@xxxxxxxxxxx> > > > Omar, > > Tried running this with my original reproducer (qcow2 snapshotting and > rebooting) and got the following: > ------------[ cut here ]------------ > kernel BUG at fs/ext4/indirect.c:1488! > invalid opcode: 0000 [#1] SMP > <snip> > CPU: 4 PID: 9771 Comm: qemu-img Tainted: G W E > 3.19.0-rc7-b164aa5 #22 > Hardware name: XXX > task: ffff880243a34aa0 ti: ffff880240f3c000 task.ti: ffff880240f3c000 > RIP: 0010:[<ffffffff812a38e7>] [<ffffffff812a38e7>] > ext4_ind_remove_space+0x737/0x740 > RSP: 0018:ffff880240f3fc98 EFLAGS: 00010246 > RAX: ffff880240f3fd98 RBX: ffff880240f3fd98 RCX: ffff880098c684dc > RDX: ffff880098c684d4 RSI: ffff880240f3fd08 RDI: ffff880098c684e0 > RBP: ffff880240f3fdf8 R08: ffff880098c684e0 R09: 0000000000000000 > R10: ffff880240f3faa0 R11: 0000000000000038 R12: ffff88009bb65810 > R13: 0000000000000003 R14: ffff880240f3fd08 R15: ffff880240f3fd68 > FS: 00007f7ad84ad700(0000) GS:ffff88024e500000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f7ae19a78ff CR3: 0000000241c52000 CR4: 00000000003427e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Stack: > ffffea0002596600 ffff88009bb65960 0000000000000050 0000000000000100 > ffff8802447a2900 0000000000000003 ffff880240f3fd08 ffff88009b96c030 > ffff880240f3fd08 000000000000024b 000000000000000d ffff880000000034 > Call Trace: > [<ffffffff8129ccdc>] ? ext4_discard_preallocations+0x16c/0x480 > [<ffffffff8126982f>] ext4_punch_hole+0x3bf/0x430 > [<ffffffff81293c9e>] ext4_fallocate+0x16e/0x8c0 > [<ffffffff811e4849>] ? __sb_start_write+0x49/0xf0 > [<ffffffff811df3cf>] vfs_fallocate+0x12f/0x250 > [<ffffffff810eda41>] ? SyS_futex+0x71/0x150 > [<ffffffff811e0408>] SyS_fallocate+0x48/0x80 > [<ffffffff8177cc2d>] system_call_fastpath+0x16/0x1b > Code: 40 4c 8d 0c c5 e8 ff ff ff 49 c1 f9 03 45 69 c9 ab aa aa aa e8 6b > e2 ff ff 48 8b 85 10 ff ff ff c7 00 00 00 00 00 e9 fd fa ff ff <0f> 0b > 0f 0b 0f 1f 44 00 00 0f 1f 44 00 00 55 48 89 e5 41 56 41 > RIP [<ffffffff812a38e7>] ext4_ind_remove_space+0x737/0x740 > RSP <ffff880240f3fc98> > ---[ end trace 05f053fdd5d908a8 ]--- > > So this is hitting the BUG_ON you added. > --chris > Ah, yes, thanks Chris, my logic there was wrong. For example, punching from the beginning of the first doubly-indirected block to, say, the 100th doubly-indirected block, will hit this. Gimme a sec and I'll fix it. -- Omar -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
