Acked-by: Joel Becker <jlbec@xxxxxxxxxxxx>
On Wed, Feb 27, 2013 at 05:02:49PM -0800, akpm@xxxxxxxxxxxxxxxxxxxx wrote:
> From: "Xiaowei.Hu" <xiaowei.hu@xxxxxxxxxx>
> Subject: ocfs2: ac->ac_allow_chain_relink=0 won't disable group relink
>
> 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)
> Stack:
> 00000001b919b5c8 ffff880159f652d0 ffff8801f565cc70 ffff880087f09bf8
> 000000000010e000 ffff88016da2f000 ffff8801b919b618 ffffffffa0865e4f
> 0000000000000000 ffff8801f565cc70 ffff880159f652d0 ffff8801fdc76e40
> Call Trace:
> [<ffffffffa0865e4f>] ocfs2_journal_dirty+0x2f/0x70 [ocfs2]
> [<ffffffffa0889441>] ocfs2_relink_block_group+0x111/0x480 [ocfs2]
> [<ffffffffa088cda5>] ocfs2_search_chain+0x455/0x9a0 [ocfs2]
> ...
>
> Signed-off-by: Xiaowei.Hu <xiaowei.hu@xxxxxxxxxx>
> Reviewed-by: Srinivas Eeda <srinivas.eeda@xxxxxxxxxx>
> Cc: Mark Fasheh <mfasheh@xxxxxxxx>
> Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
>
> fs/ocfs2/suballoc.c | 7 +++----
> fs/ocfs2/suballoc.h | 2 +-
> 2 files changed, 4 insertions(+), 5 deletions(-)
>
> diff -puN fs/ocfs2/suballoc.c~ocfs2-ac-ac_allow_chain_relink=0-wont-disable-group-relink fs/ocfs2/suballoc.c
> --- a/fs/ocfs2/suballoc.c~ocfs2-ac-ac_allow_chain_relink=0-wont-disable-group-relink
> +++ a/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;
> diff -puN fs/ocfs2/suballoc.h~ocfs2-ac-ac_allow_chain_relink=0-wont-disable-group-relink fs/ocfs2/suballoc.h
> --- a/fs/ocfs2/suballoc.h~ocfs2-ac-ac_allow_chain_relink=0-wont-disable-group-relink
> +++ a/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;
> _
--
Life's Little Instruction Book #267
"Lie on your back and look at the stars."
http://www.jlbec.org/
jlbec@xxxxxxxxxxxx
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