On Tue, Feb 07, 2017 at 06:14:59PM +0100, Christoph Hellwig wrote:
> Currently we force the log and simply try again if we hit a busy extent,
> but especially with online discard enabled it might take a while after
> the log force for the busy extents to disappear, and we might have
> already completed our second pass.
>
> So instead we add a new waitqueue and a generation counter to the pag
> structure so that we can do wakeups once we've removed busy extents,
> and we replace the single retry with an unconditional one - after
> all we hold the AGF buffer lock, so no other allocations or frees
> can be racing with us in this AG.
Um... is this patch supposed to be merged with the previous one?
They have the same subject/commit message.
(Patch itself looks fine, I think.)
--D
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/xfs/xfs_extent_busy.c | 32 ++++++++++++++++++++++++++++----
> fs/xfs/xfs_extent_busy.h | 5 ++++-
> fs/xfs/xfs_mount.c | 7 +++++++
> 3 files changed, 39 insertions(+), 5 deletions(-)
>
> diff --git a/fs/xfs/xfs_extent_busy.c b/fs/xfs/xfs_extent_busy.c
> index 27c3ecb138e4..4d850e27095e 100644
> --- a/fs/xfs/xfs_extent_busy.c
> +++ b/fs/xfs/xfs_extent_busy.c
> @@ -335,10 +335,11 @@ xfs_extent_busy_reuse(
> * args->minlen no suitable extent could be found, and the higher level
> * code needs to force out the log and retry the allocation.
> *
> - * Return the current discard generation for the AG if the file system
> - * has online discard enabled. This value can be used to wait for
> - * the trimmed extent to become fully available if the AG is running out
> - * of space.
> + * Return the current busy generation for the AG if the extent is busy. This
> + * value can be used to wait for at least one of the currently busy extents
> + * to be cleared. Note that the busy list is not guaranteed to be empty after
> + * the gen is woken. The state of a specific extent must always be confirmed
> + * with another call to xfs_extent_busy_trim() before it can be used.
> */
> bool
> xfs_extent_busy_trim(
> @@ -510,6 +511,7 @@ xfs_extent_busy_trim(
> flen = fend - fbno;
> }
> out:
> +
> if (fbno != *bno || flen != *len) {
> trace_xfs_extent_busy_trim(args->mp, args->agno, *bno, *len,
> fbno, flen);
> @@ -626,6 +628,28 @@ xfs_extent_busy_flush(
> finish_wait(&pag->pagb_wait, &wait);
> }
>
> +void
> +xfs_extent_busy_wait_all(
> + struct xfs_mount *mp)
> +{
> + DEFINE_WAIT (wait);
> + xfs_agnumber_t agno;
> +
> + for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
> + struct xfs_perag *pag = xfs_perag_get(mp, agno);
> +
> + do {
> + prepare_to_wait(&pag->pagb_wait, &wait, TASK_KILLABLE);
> + if (RB_EMPTY_ROOT(&pag->pagb_tree))
> + break;
> + schedule();
> + } while (1);
> + finish_wait(&pag->pagb_wait, &wait);
> +
> + xfs_perag_put(pag);
> + }
> +}
> +
> /*
> * Callback for list_sort to sort busy extents by the AG they reside in.
> */
> diff --git a/fs/xfs/xfs_extent_busy.h b/fs/xfs/xfs_extent_busy.h
> index bcb99463cfbb..60195ea1b84a 100644
> --- a/fs/xfs/xfs_extent_busy.h
> +++ b/fs/xfs/xfs_extent_busy.h
> @@ -64,7 +64,10 @@ xfs_extent_busy_trim(struct xfs_alloc_arg *args, xfs_agblock_t *bno,
>
> void
> xfs_extent_busy_flush(struct xfs_mount *mp, struct xfs_perag *pag,
> - unsigned discards);
> + unsigned busy_gen);
> +
> +void
> +xfs_extent_busy_wait_all(struct xfs_mount *mp);
>
> int
> xfs_extent_busy_ag_cmp(void *priv, struct list_head *a, struct list_head *b);
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index 4e9feb1dc15d..e87618d47871 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -45,6 +45,7 @@
> #include "xfs_rmap_btree.h"
> #include "xfs_refcount_btree.h"
> #include "xfs_reflink.h"
> +#include "xfs_extent_busy.h"
>
>
> static DEFINE_MUTEX(xfs_uuid_table_mutex);
> @@ -1074,6 +1075,12 @@ xfs_unmountfs(
> xfs_log_force(mp, XFS_LOG_SYNC);
>
> /*
> + * Wait for all busy extents to be freed, including completion of
> + * any discard operation.
> + */
> + xfs_extent_busy_wait_all(mp);
> +
> + /*
> * We now need to tell the world we are unmounting. This will allow
> * us to detect that the filesystem is going away and we should error
> * out anything that we have been retrying in the background. This will
> --
> 2.11.0
>
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