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    Subject[ 14/46] ocfs2: ac->ac_allow_chain_relink=0 wont disable group relink
    Date
    3.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: "Xiaowei.Hu" <xiaowei.hu@oracle.com>

    commit 309a85b6861fedbb48a22d45e0e079d1be993b3a upstream.

    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: Xiaowei.Hu <xiaowei.hu@oracle.com>
    Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
    Cc: Mark Fasheh <mfasheh@suse.com>
    Cc: Joel Becker <jlbec@evilplan.org>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/ocfs2/suballoc.c | 7 +++----
    fs/ocfs2/suballoc.h | 2 +-
    2 files changed, 4 insertions(+), 5 deletions(-)

    --- a/fs/ocfs2/suballoc.c
    +++ b/fs/ocfs2/suballoc.c
    @@ -642,7 +642,7 @@ ocfs2_block_group_alloc_discontig(handle
    * cluster groups will be staying in cache for the duration of
    * this operation.
    */
    - ac->ac_allow_chain_relink = 0;
    + ac->ac_disable_chain_relink = 1;

    /* Claim the first region */
    status = ocfs2_block_group_claim_bits(osb, handle, ac, min_bits,
    @@ -1823,7 +1823,7 @@ static int ocfs2_search_chain(struct ocf
    * Do this *after* figuring out how many bits we're taking out
    * of our target group.
    */
    - if (ac->ac_allow_chain_relink &&
    + if (!ac->ac_disable_chain_relink &&
    (prev_group_bh) &&
    (ocfs2_block_group_reasonably_empty(bg, res->sr_bits))) {
    status = ocfs2_relink_block_group(handle, alloc_inode,
    @@ -1928,7 +1928,6 @@ static int ocfs2_claim_suballoc_bits(str

    victim = ocfs2_find_victim_chain(cl);
    ac->ac_chain = victim;
    - ac->ac_allow_chain_relink = 1;

    status = ocfs2_search_chain(ac, handle, bits_wanted, min_bits,
    res, &bits_left);
    @@ -1947,7 +1946,7 @@ static int ocfs2_claim_suballoc_bits(str
    * searching each chain in order. Don't allow chain relinking
    * because we only calculate enough journal credits for one
    * relink per alloc. */
    - ac->ac_allow_chain_relink = 0;
    + ac->ac_disable_chain_relink = 1;
    for (i = 0; i < le16_to_cpu(cl->cl_next_free_rec); i ++) {
    if (i == victim)
    continue;
    --- a/fs/ocfs2/suballoc.h
    +++ b/fs/ocfs2/suballoc.h
    @@ -49,7 +49,7 @@ struct ocfs2_alloc_context {

    /* these are used by the chain search */
    u16 ac_chain;
    - int ac_allow_chain_relink;
    + int ac_disable_chain_relink;
    group_search_t *ac_group_search;

    u64 ac_last_group;



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