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-rw-r--r--mm/Kconfig13
-rw-r--r--mm/bounce.c48
-rw-r--r--mm/page-writeback.c4
3 files changed, 61 insertions, 4 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index 278e3ab1f169..7901d839aab2 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -258,6 +258,19 @@ config BOUNCE
def_bool y
depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
+# On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often
+# have more than 4GB of memory, but we don't currently use the IOTLB to present
+# a 32-bit address to OHCI. So we need to use a bounce pool instead.
+#
+# We also use the bounce pool to provide stable page writes for jbd. jbd
+# initiates buffer writeback without locking the page or setting PG_writeback,
+# and fixing that behavior (a second time; jbd2 doesn't have this problem) is
+# a major rework effort. Instead, use the bounce buffer to snapshot pages
+# (until jbd goes away). The only jbd user is ext3.
+config NEED_BOUNCE_POOL
+ bool
+ default y if (TILE && USB_OHCI_HCD) || (BLK_DEV_INTEGRITY && JBD)
+
config NR_QUICK
int
depends on QUICKLIST
diff --git a/mm/bounce.c b/mm/bounce.c
index 042086775561..5f8901768602 100644
--- a/mm/bounce.c
+++ b/mm/bounce.c
@@ -178,8 +178,45 @@ static void bounce_end_io_read_isa(struct bio *bio, int err)
__bounce_end_io_read(bio, isa_page_pool, err);
}
+#ifdef CONFIG_NEED_BOUNCE_POOL
+static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio)
+{
+ struct page *page;
+ struct backing_dev_info *bdi;
+ struct address_space *mapping;
+ struct bio_vec *from;
+ int i;
+
+ if (bio_data_dir(bio) != WRITE)
+ return 0;
+
+ if (!bdi_cap_stable_pages_required(&q->backing_dev_info))
+ return 0;
+
+ /*
+ * Based on the first page that has a valid mapping, decide whether or
+ * not we have to employ bounce buffering to guarantee stable pages.
+ */
+ bio_for_each_segment(from, bio, i) {
+ page = from->bv_page;
+ mapping = page_mapping(page);
+ if (!mapping)
+ continue;
+ bdi = mapping->backing_dev_info;
+ return mapping->host->i_sb->s_flags & MS_SNAP_STABLE;
+ }
+
+ return 0;
+}
+#else
+static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio)
+{
+ return 0;
+}
+#endif /* CONFIG_NEED_BOUNCE_POOL */
+
static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
- mempool_t *pool)
+ mempool_t *pool, int force)
{
struct page *page;
struct bio *bio = NULL;
@@ -192,7 +229,7 @@ static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
/*
* is destination page below bounce pfn?
*/
- if (page_to_pfn(page) <= queue_bounce_pfn(q))
+ if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force)
continue;
/*
@@ -270,6 +307,7 @@ static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
{
+ int must_bounce;
mempool_t *pool;
/*
@@ -278,13 +316,15 @@ void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
if (!bio_has_data(*bio_orig))
return;
+ must_bounce = must_snapshot_stable_pages(q, *bio_orig);
+
/*
* for non-isa bounce case, just check if the bounce pfn is equal
* to or bigger than the highest pfn in the system -- in that case,
* don't waste time iterating over bio segments
*/
if (!(q->bounce_gfp & GFP_DMA)) {
- if (queue_bounce_pfn(q) >= blk_max_pfn)
+ if (queue_bounce_pfn(q) >= blk_max_pfn && !must_bounce)
return;
pool = page_pool;
} else {
@@ -295,7 +335,7 @@ void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
/*
* slow path
*/
- __blk_queue_bounce(q, bio_orig, pool);
+ __blk_queue_bounce(q, bio_orig, pool, must_bounce);
}
EXPORT_SYMBOL(blk_queue_bounce);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 355d5ee69058..7300c9d5e1d9 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2306,6 +2306,10 @@ void wait_for_stable_page(struct page *page)
if (!bdi_cap_stable_pages_required(bdi))
return;
+#ifdef CONFIG_NEED_BOUNCE_POOL
+ if (mapping->host->i_sb->s_flags & MS_SNAP_STABLE)
+ return;
+#endif /* CONFIG_NEED_BOUNCE_POOL */
wait_on_page_writeback(page);
}