• David Howells's avatar
    FS-Cache: Add a helper to bulk uncache pages on an inode · c902ce1b
    David Howells authored
    Add an FS-Cache helper to bulk uncache pages on an inode.  This will
    only work for the circumstance where the pages in the cache correspond
    1:1 with the pages attached to an inode's page cache.
    This is required for CIFS and NFS: When disabling inode cookie, we were
    returning the cookie and setting cifsi->fscache to NULL but failed to
    invalidate any previously mapped pages.  This resulted in "Bad page
    state" errors and manifested in other kind of errors when running
    fsstress.  Fix it by uncaching mapped pages when we disable the inode
    This patch should fix the following oops and "Bad page state" errors
    seen during fsstress testing.
      ------------[ cut here ]------------
      kernel BUG at fs/cachefiles/namei.c:201!
      invalid opcode: 0000 [#1] SMP
      Pid: 5, comm: kworker/u:0 Not tainted #1 Bochs Bochs
      RIP: 0010: cachefiles_walk_to_object+0x436/0x745 [cachefiles]
      RSP: 0018:ffff88002ce6dd00  EFLAGS: 00010282
      RAX: ffff88002ef165f0 RBX: ffff88001811f500 RCX: 0000000000000000
      RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000282
      RBP: ffff88002ce6dda0 R08: 0000000000000100 R09: ffffffff81b3a300
      R10: 0000ffff00066c0a R11: 0000000000000003 R12: ffff88002ae54840
      R13: ffff88002ae54840 R14: ffff880029c29c00 R15: ffff88001811f4b0
      FS:  00007f394dd32720(0000) GS:ffff88002ef00000(0000) knlGS:0000000000000000
      CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
      CR2: 00007fffcb62ddf8 CR3: 000000001825f000 CR4: 00000000000006e0
      DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
      DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
      Process kworker/u:0 (pid: 5, threadinfo ffff88002ce6c000, task ffff88002ce55cc0)
       0000000000000246 ffff88002ce55cc0 ffff88002ce6dd58 ffff88001815dc00
       ffff8800185246c0 ffff88001811f618 ffff880029c29d18 ffff88001811f380
       ffff88002ce6dd50 ffffffff814757e4 ffff88002ce6dda0 ffffffff8106ac56
      Call Trace:
       cachefiles_lookup_object+0x78/0xd4 [cachefiles]
       fscache_lookup_object+0x131/0x16d [fscache]
       fscache_object_work_func+0x1bc/0x669 [fscache]
      RIP  cachefiles_walk_to_object+0x436/0x745 [cachefiles]
      ---[ end trace 1d481c9af1804caa ]---
    I tested the uncaching by the following means:
     (1) Create a big file on my NFS server (104857600 bytes).
     (2) Read the file into the cache with md5sum on the NFS client.  Look in
    	Pages  : mrk=25601 unc=0
     (3) Open the file for read/write ("bash 5<>/warthog/bigfile").  Look in proc
    	Pages  : mrk=25601 unc=25601
    Reported-by: default avatarJeff Layton <jlayton@redhat.com>
    Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
    Reviewed-and-Tested-by: default avatarSuresh Jayaraman <sjayaraman@suse.de>
    cc: stable@kernel.org
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
fscache.h 21.5 KB