• Dave Kleikamp's avatar
    nfs: don't dirty kernel pages read by direct-io · ad3cba22
    Dave Kleikamp authored
    When we use direct_IO with an NFS backing store, we can trigger a
    WARNING in __set_page_dirty(), as below, since we're dirtying the page
    unnecessarily in nfs_direct_read_completion().
    
    To fix, replicate the logic in commit 53cbf3b1 ("fs: direct-io:
    don't dirtying pages for ITER_BVEC/ITER_KVEC direct read").
    
    Other filesystems that implement direct_IO handle this; most use
    blockdev_direct_IO(). ceph and cifs have similar logic.
    
    mount 127.0.0.1:/export /nfs
    dd if=/dev/zero of=/nfs/image bs=1M count=200
    losetup --direct-io=on -f /nfs/image
    mkfs.btrfs /dev/loop0
    mount -t btrfs /dev/loop0 /mnt/
    
    kernel: WARNING: CPU: 0 PID: 8067 at fs/buffer.c:580 __set_page_dirty+0xaf/0xd0
    kernel: Modules linked in: loop(E) nfsv3(E) rpcsec_gss_krb5(E) nfsv4(E) dns_resolver(E) nfs(E) fscache(E) nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E) grace(E) fuse(E) tun(E) ip6t_rpfilter(E) ipt_REJECT(E) nf_
    kernel:  snd_seq(E) snd_seq_device(E) snd_pcm(E) video(E) snd_timer(E) snd(E) soundcore(E) ip_tables(E) xfs(E) libcrc32c(E) sd_mod(E) sr_mod(E) cdrom(E) ata_generic(E) pata_acpi(E) crc32c_intel(E) ahci(E) li
    kernel: CPU: 0 PID: 8067 Comm: kworker/0:2 Tainted: G            E     4.20.0-rc1.master.20181111.ol7.x86_64 #1
    kernel: Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
    kernel: Workqueue: nfsiod rpc_async_release [sunrpc]
    kernel: RIP: 0010:__set_page_dirty+0xaf/0xd0
    kernel: Code: c3 48 8b 02 f6 c4 04 74 d4 48 89 df e8 ba 05 f7 ff 48 89 c6 eb cb 48 8b 43 08 a8 01 75 1f 48 89 d8 48 8b 00 a8 04 74 02 eb 87 <0f> 0b eb 83 48 83 e8 01 eb 9f 48 83 ea 01 0f 1f 00 eb 8b 48 83 e8
    kernel: RSP: 0000:ffffc1c8825b7d78 EFLAGS: 00013046
    kernel: RAX: 000fffffc0020089 RBX: fffff2b603308b80 RCX: 0000000000000001
    kernel: RDX: 0000000000000001 RSI: ffff9d11478115c8 RDI: ffff9d11478115d0
    kernel: RBP: ffffc1c8825b7da0 R08: 0000646f6973666e R09: 8080808080808080
    kernel: R10: 0000000000000001 R11: 0000000000000000 R12: ffff9d11478115d0
    kernel: R13: ffff9d11478115c8 R14: 0000000000003246 R15: 0000000000000001
    kernel: FS:  0000000000000000(0000) GS:ffff9d115ba00000(0000) knlGS:0000000000000000
    kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    kernel: CR2: 00007f408686f640 CR3: 0000000104d8e004 CR4: 00000000000606f0
    kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    kernel: Call Trace:
    kernel:  __set_page_dirty_buffers+0xb6/0x110
    kernel:  set_page_dirty+0x52/0xb0
    kernel:  nfs_direct_read_completion+0xc4/0x120 [nfs]
    kernel:  nfs_pgio_release+0x10/0x20 [nfs]
    kernel:  rpc_free_task+0x30/0x70 [sunrpc]
    kernel:  rpc_async_release+0x12/0x20 [sunrpc]
    kernel:  process_one_work+0x174/0x390
    kernel:  worker_thread+0x4f/0x3e0
    kernel:  kthread+0x102/0x140
    kernel:  ? drain_workqueue+0x130/0x130
    kernel:  ? kthread_stop+0x110/0x110
    kernel:  ret_from_fork+0x35/0x40
    kernel: ---[ end trace 01341980905412c9 ]---
    Signed-off-by: 's avatarDave Kleikamp <dave.kleikamp@oracle.com>
    Signed-off-by: 's avatarSantosh Shilimkar <santosh.shilimkar@oracle.com>
    
    [forward-ported to v4.20]
    Signed-off-by: 's avatarCalum Mackay <calum.mackay@oracle.com>
    Reviewed-by: 's avatarDave Kleikamp <dave.kleikamp@oracle.com>
    Reviewed-by: 's avatarChuck Lever <chuck.lever@oracle.com>
    Signed-off-by: 's avatarTrond Myklebust <trond.myklebust@hammerspace.com>
    ad3cba22
direct.c 28.9 KB