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Message-ID: <alpine.LFD.2.00.1402201207410.2245@localhost.localdomain> Date: Thu, 20 Feb 2014 12:16:26 +0100 (CET) From: Lukáš Czerner <lczerner@...hat.com> To: Dongsu Park <dongsu.park@...fitbricks.com> cc: linux-ext4 <linux-ext4@...r.kernel.org>, tytso <tytso@....edu>, linux-fsdevel <linux-fsdevel@...r.kernel.org>, xfs <xfs@....sgi.com> Subject: Re: [PATCH 0/6][RFC] Introduce FALLOC_FL_ZERO_RANGE flag for fallocate On Wed, 19 Feb 2014, Dongsu Park wrote: > Date: Wed, 19 Feb 2014 16:51:23 +0100 > From: Dongsu Park <dongsu.park@...fitbricks.com> > To: Lukáš Czerner <lczerner@...hat.com> > Cc: linux-ext4 <linux-ext4@...r.kernel.org>, tytso <tytso@....edu>, > linux-fsdevel <linux-fsdevel@...r.kernel.org>, xfs <xfs@....sgi.com> > Subject: Re: [PATCH 0/6][RFC] Introduce FALLOC_FL_ZERO_RANGE flag for > fallocate > > On Wed, Feb 19, 2014 at 4:18 PM, Lukáš Czerner <lczerner@...hat.com> wrote: > > On Wed, 19 Feb 2014, Dongsu Park wrote: > > Are you able to reproduce it ? Can you tell me the steps to > > reproduce this ? The problem is that the extent we're trying to mark > > as uninitialized has zero length.... > > > > Ah...I can probably see what is going on. For some inexplicable > > reason I am forgetting to take i_data_sem which means that we're > > probably racing with truncate or something else. > > > > Thanks a lot for letting me know and If you can please send me a > > reproducer for your case because as I said I have not seen this > > before. > > Yes, it's reliably reproducible. > What I'm doing for testing is quite simple, just like that: > (/dev/vdb is a test block device, 16GiB in size) > > # mke2fs -t ext4 /dev/vdb > # mkdir -p /mnt/test1 > # mount -t ext4 -o discard /dev/vdb /mnt/test1 > # dd if=/dev/urandom of=/mnt/test1/file1 bs=2G count=1 > # fallocate -z -l 2G /mnt/test1/file1 > > Then kernel crashes immediately. Oh, now I know where the problem really is. It's not about the locking at all. Initialized and Uninitialized extents have different maximum size. So we can not convert initialized extent of a maximum size to a uninitialized extent right away. We have to split. Thank you, your testing is very useful! -Lukas > > Cheers, > Dongsu > > > Thanks! > > -Lukas > > > > > > > > ------------[ cut here ]------------ > > > kernel BUG at fs/ext4/ext4_extents.h:193! > > > invalid opcode: 0000 [#1] SMP > > > Modules linked in: 9pnet_virtio virtio_net 9pnet virtio_blk virtio_pci > > > virtio_ring virtio > > > CPU: 2 PID: 2959 Comm: fallocate Not tainted 3.14.0-rc3+ #34 > > > Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 > > > task: ffff8800da97da10 ti: ffff880119068000 task.ti: ffff880119068000 > > > RIP: 0010:[<ffffffff813694c9>] [<ffffffff813694c9>] > > > ext4_ext_map_blocks+0x2899/0x2940 > > > RSP: 0018:ffff880119069c50 EFLAGS: 00010202 > > > RAX: 0000000000000003 RBX: ffff880036fa8470 RCX: 0000000000000002 > > > RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff82120e98 > > > RBP: ffff880119069d30 R08: ffff88011975d900 R09: 011ad15618080000 > > > R10: fec72ef09c4d8602 R11: 0000000000008000 R12: ffff880119069dd0 > > > R13: 0000000000000403 R14: 0000000000000001 R15: ffff880118c6700c > > > FS: 00007fa54a0ba740(0000) GS:ffff88011fc40000(0000) > > > knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: 0000003cdbf6f7e0 CR3: 0000000119077000 CR4: 00000000000006e0 > > > Stack: > > > 0000000000000000 0000000000008000 ffff880036fa86c8 0000000000000000 > > > ffff880100000000 0000800081384dee 0000000000000001 ffff880000000000 > > > 0000000000008800 0000000000000000 ffff880036f6f000 ffff88011975d900 > > > Call Trace: > > > [<ffffffff81385baa>] ? ext4_es_insert_extent+0x15a/0x240 > > > [<ffffffff813669ae>] ? ext4_find_delalloc_range+0x1e/0xb0 > > > [<ffffffff81322d3f>] ext4_map_blocks+0x25f/0x830 > > > [<ffffffff81369764>] ? ext4_alloc_file_blocks+0xc4/0x1e0 > > > [<ffffffff813697da>] ext4_alloc_file_blocks+0x13a/0x1e0 > > > [<ffffffff81369e9f>] ext4_zero_range+0x61f/0x870 > > > [<ffffffff8136a5d3>] ext4_fallocate+0x4e3/0x6c0 > > > [<ffffffff81239675>] ? __sb_start_write+0x145/0x1a0 > > > [<ffffffff8120ef00>] ? kmem_cache_free+0x2f0/0x3f0 > > > [<ffffffff81246ca0>] ? final_putname+0x30/0x60 > > > [<ffffffff812326a7>] do_fallocate+0x1e7/0x290 > > > [<ffffffff812327c9>] SyS_fallocate+0x79/0xc0 > > > [<ffffffff81ae7de9>] system_call_fastpath+0x16/0x1b > > > Code: ba dc 05 00 00 48 c7 c6 b0 91 c7 81 48 89 df 89 04 24 31 c0 e8 99 > > > 83 fe ff e9 f5 f8 ff ff 48 83 05 34 b3 f5 00 01 e9 0a db ff ff <0f> 0b > > > 0f 0b 0f 0b 0f 0b 45 89 d1 49 c7 c0 48 22 e5 81 31 > > > RIP [<ffffffff813694c9>] ext4_ext_map_blocks+0x2899/0x2940 > > > RSP <ffff880119069c50> > > > ---[ end trace ba21204a3a98fbdc ]--- > > > > > > Regards, > > > Dongsu > > > > > > > I'll post the patches after we agree and merge the kernel functionality. > > > > > > > > I tested this mostly with a subset of xfstests using fsx and fsstress and > > > > even with new generic/290 which is just a copy of xfs/290 usinz fzero > > > > command for xfs_io instead of zero (which uses ioctl). I was testing on > > > > x86_64 and ppc64 with block sizes of 1024, 2048 and 4096. > > > > > > > > ./check generic/076 generic/232 generic/013 generic/070 generic/269 generic/083 generic/117 generic/068 generic/231 generic/127 generic/091 generic/075 generic/112 generic/263 generic/091 generic/075 generic/256 generic/255 generic/316 generic/300 generic/290; > > > > > > > > Note that there is a work in progress on FALLOC_FL_COLLAPSE_RANGE which > > > > touches the same area as this pach set does, so we should figure out > > > > which one should go first and modify the other on top of it. > > > > > > > > Thanks! > > > > -Lukas > > > > > > > > -- > > > > [PATCH 1/6] ext4: Update inode i_size after the preallocation > > > > [PATCH 2/6] ext4: refactor ext4_fallocate code > > > > [PATCH 3/6] ext4: translate fallocate mode bits to strings > > > > [PATCH 4/6] fs: Introduce FALLOC_FL_ZERO_RANGE flag for fallocate > > > > [PATCH 5/6] ext4: Introduce FALLOC_FL_ZERO_RANGE flag for fallocate > > > > [PATCH 6/6] xfs: Add support for FALLOC_FL_ZERO_RANGE > > > > > > > > fs/ext4/ext4.h | 3 + > > > > fs/ext4/extents.c | 430 ++++++++++++++++++++++++++++++++++++++++++++++++++++---------------- > > > > fs/ext4/inode.c | 17 ++- > > > > fs/open.c | 7 +- > > > > fs/xfs/xfs_file.c | 10 +- > > > > include/trace/events/ext4.h | 67 ++++++----- > > > > include/uapi/linux/falloc.h | 1 + > > > > 7 files changed, 393 insertions(+), 142 deletions(-) > > > > -- > > > > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > > > > the body of a message to majordomo@...r.kernel.org > > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > >
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