NAK, if ocfs2_try_to_free_truncate_log fails, it will lead to double
ocfs2_inode_unlock and then BUG.
On 2016/6/22 17:07, Eric Ren wrote:
> The testcase "mmaptruncate" in ocfs2 test suite always fails with
> ENOSPC error on small volume (say less than 10G). This testcase
> creates 2 threads T1/T2 which race to "truncate"/"extend" a same
> file repeatedly. Specifically, T1 truncates 1/2 size of a small file
> while T2 extend to 100% size. The main bitmap will quickly run out
> of space because the "truncate" code prevent truncate log from being
> flushed by ocfs2_schedule_truncate_log_flush(osb, 1), while truncate
> log may have cached lots of clusters.
>
> So retry to allocate after flushing truncate log when ENOSPC is
> returned. And we cannot reuse the deleted blocks before the transaction
> committed. Fortunately, we already have a function to do this -
> ocfs2_try_to_free_truncate_log(). Just need to remove the "static"
> modifier and put it into a right place.
>
> Signed-off-by: Eric Ren <z...@suse.com>
> ---
> fs/ocfs2/alloc.c | 37 +++++++++++++++++++++++++++++++++++++
> fs/ocfs2/alloc.h | 2 ++
> fs/ocfs2/aops.c | 37 -------------------------------------
> fs/ocfs2/suballoc.c | 17 ++++++++++++++++-
> 4 files changed, 55 insertions(+), 38 deletions(-)
>
> diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
> index 460c0ce..7dabbc3 100644
> --- a/fs/ocfs2/alloc.c
> +++ b/fs/ocfs2/alloc.c
> @@ -6106,6 +6106,43 @@ void ocfs2_schedule_truncate_log_flush(struct
> ocfs2_super *osb,
> }
> }
>
> +/*
> + * Try to flush truncate logs if we can free enough clusters from it.
> + * As for return value, "< 0" means error, "0" no space and "1" means
> + * we have freed enough spaces and let the caller try to allocate again.
> + */
> +int ocfs2_try_to_free_truncate_log(struct ocfs2_super *osb,
> + unsigned int needed)
> +{
> + tid_t target;
> + int ret = 0;
> + unsigned int truncated_clusters;
> +
> + inode_lock(osb->osb_tl_inode);
> + truncated_clusters = osb->truncated_clusters;
> + inode_unlock(osb->osb_tl_inode);
> +
> + /*
> + * Check whether we can succeed in allocating if we free
> + * the truncate log.
> + */
> + if (truncated_clusters < needed)
> + goto out;
> +
> + ret = ocfs2_flush_truncate_log(osb);
> + if (ret) {
> + mlog_errno(ret);
> + goto out;
> + }
> +
> + if (jbd2_journal_start_commit(osb->journal->j_journal, &target)) {
> + jbd2_log_wait_commit(osb->journal->j_journal, target);
> + ret = 1;
> + }
> +out:
> + return ret;
> +}
> +
> static int ocfs2_get_truncate_log_info(struct ocfs2_super *osb,
> int slot_num,
> struct inode **tl_inode,
> diff --git a/fs/ocfs2/alloc.h b/fs/ocfs2/alloc.h
> index f3dc1b0..4a5152e 100644
> --- a/fs/ocfs2/alloc.h
> +++ b/fs/ocfs2/alloc.h
> @@ -188,6 +188,8 @@ int ocfs2_truncate_log_append(struct ocfs2_super *osb,
> u64 start_blk,
> unsigned int num_clusters);
> int __ocfs2_flush_truncate_log(struct ocfs2_super *osb);
> +int ocfs2_try_to_free_truncate_log(struct ocfs2_super *osb,
> + unsigned int needed);
>
> /*
> * Process local structure which describes the block unlinks done
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index c034edf..1802aef 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -1645,43 +1645,6 @@ static int ocfs2_zero_tail(struct inode *inode, struct
> buffer_head *di_bh,
> return ret;
> }
>
> -/*
> - * Try to flush truncate logs if we can free enough clusters from it.
> - * As for return value, "< 0" means error, "0" no space and "1" means
> - * we have freed enough spaces and let the caller try to allocate again.
> - */
> -static int ocfs2_try_to_free_truncate_log(struct ocfs2_super *osb,
> - unsigned int needed)
> -{
> - tid_t target;
> - int ret = 0;
> - unsigned int truncated_clusters;
> -
> - inode_lock(osb->osb_tl_inode);
> - truncated_clusters = osb->truncated_clusters;
> - inode_unlock(osb->osb_tl_inode);
> -
> - /*
> - * Check whether we can succeed in allocating if we free
> - * the truncate log.
> - */
> - if (truncated_clusters < needed)
> - goto out;
> -
> - ret = ocfs2_flush_truncate_log(osb);
> - if (ret) {
> - mlog_errno(ret);
> - goto out;
> - }
> -
> - if (jbd2_journal_start_commit(osb->journal->j_journal, &target)) {
> - jbd2_log_wait_commit(osb->journal->j_journal, target);
> - ret = 1;
> - }
> -out:
> - return ret;
> -}
> -
> int ocfs2_write_begin_nolock(struct address_space *mapping,
> loff_t pos, unsigned len, ocfs2_write_type_t type,
> struct page **pagep, void **fsdata,
> diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
> index 2f19aee..9f7f3b6 100644
> --- a/fs/ocfs2/suballoc.c
> +++ b/fs/ocfs2/suballoc.c
> @@ -1164,7 +1164,8 @@ static int ocfs2_reserve_clusters_with_limit(struct
> ocfs2_super *osb,
> int flags,
> struct ocfs2_alloc_context **ac)
> {
> - int status;
> + int status, ret = 0;
> + int retried = 0;
>
> *ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
> if (!(*ac)) {
> @@ -1189,7 +1190,21 @@ static int ocfs2_reserve_clusters_with_limit(struct
> ocfs2_super *osb,
> }
>
> if (status == -ENOSPC) {
> +retry:
> status = ocfs2_reserve_cluster_bitmap_bits(osb, *ac);
> + /* Retry if there is sufficient space cached in truncate log */
> + if (status == -ENOSPC && !retried) {
> + retried = 1;
> + ocfs2_inode_unlock((*ac)->ac_inode, 1);
> + inode_unlock((*ac)->ac_inode);
> +
> + ret = ocfs2_try_to_free_truncate_log(osb, bits_wanted);
> + if (ret == 1)
> + goto retry;
> +
> + if (ret < 0)
> + mlog_errno(ret);
> + }
> if (status < 0) {
> if (status != -ENOSPC)
> mlog_errno(status);
>
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