• Xiaowei.Hu's avatar
    ocfs2: ac->ac_allow_chain_relink=0 won't disable group relink · 309a85b6
    Xiaowei.Hu authored
    ocfs2_block_group_alloc_discontig() disables chain relink by setting
    ac->ac_allow_chain_relink = 0 because it grabs clusters from multiple
    cluster groups.
    
    It doesn't keep the credits for all chain relink,but
    ocfs2_claim_suballoc_bits overrides this in this call trace:
    ocfs2_block_group_claim_bits()->ocfs2_claim_clusters()->
    __ocfs2_claim_clusters()->ocfs2_claim_suballoc_bits()
    ocfs2_claim_suballoc_bits set ac->ac_allow_chain_relink = 1; then call
    ocfs2_search_chain() one time and disable it again, and then we run out
    of credits.
    
    Fix is to allow relink by default and disable it in
    ocfs2_block_group_alloc_discontig.
    
    Without this patch, End-users will run into a crash due to run out of
    credits, backtrace like this:
    
      RIP: 0010:[<ffffffffa0808b14>]  [<ffffffffa0808b14>]
      jbd2_journal_dirty_metadata+0x164/0x170 [jbd2]
      RSP: 0018:ffff8801b919b5b8  EFLAGS: 00010246
      RAX: 0000000000000000 RBX: ffff88022139ddc0 RCX: ffff880159f652d0
      RDX: ffff880178aa3000 RSI: ffff880159f652d0 RDI: ffff880087f09bf8
      RBP: ffff8801b919b5e8 R08: 0000000000000000 R09: 0000000000000000
      R10: 0000000000001e00 R11: 00000000000150b0 R12: ffff880159f652d0
      R13: ffff8801a0cae908 R14: ffff880087f09bf8 R15: ffff88018d177800
      FS:  00007fc9b0b6b6e0(0000) GS:ffff88022fd40000(0000) knlGS:0000000000000000
      CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
      CR2: 000000000040819c CR3: 0000000184017000 CR4: 00000000000006e0
      DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
      DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
      Process dd (pid: 9945, threadinfo ffff8801b919a000, task ffff880149a264c0)
      Call Trace:
        ocfs2_journal_dirty+0x2f/0x70 [ocfs2]
        ocfs2_relink_block_group+0x111/0x480 [ocfs2]
        ocfs2_search_chain+0x455/0x9a0 [ocfs2]
        ...
    Signed-off-by: default avatarXiaowei.Hu <xiaowei.hu@oracle.com>
    Reviewed-by: default avatarSrinivas Eeda <srinivas.eeda@oracle.com>
    Cc: Mark Fasheh <mfasheh@suse.com>
    Cc: Joel Becker <jlbec@evilplan.org>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    309a85b6
suballoc.h 7.08 KB