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.
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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