84 lines
3.1 KiB
Diff
84 lines
3.1 KiB
Diff
From c9de2830476185f839e6cf3f9a0e5d258a534d5d Mon Sep 17 00:00:00 2001
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From: Mike Snitzer <snitzer@redhat.com>
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Date: Mon, 3 Aug 2015 09:54:58 -0400
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Subject: [PATCH] dm: fix dm_merge_bvec regression on 32 bit systems
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A DM regression on 32 bit systems was reported against v4.2-rc3 here:
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https://lkml.org/lkml/2015/7/29/401
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Fix this by reverting both commit 1c220c69 ("dm: fix casting bug in
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dm_merge_bvec()") and 148e51ba ("dm: improve documentation and code
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clarity in dm_merge_bvec"). This combined revert is done to eliminate
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the possibility of a partial revert in stable@ kernels.
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In hindsight the correct fix, at the time 1c220c69 was applied to fix
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the regression that 148e51ba introduced, should've been to simply revert
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148e51ba.
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Reported-by: Josh Boyer <jwboyer@fedoraproject.org>
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Acked-by: Joe Thornber <ejt@redhat.com>
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Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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Cc: stable@vger.kernel.org # 3.19+
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---
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drivers/md/dm.c | 27 ++++++++++-----------------
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1 file changed, 10 insertions(+), 17 deletions(-)
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diff --git a/drivers/md/dm.c b/drivers/md/dm.c
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index ab37ae114e94..0d7ab20c58df 100644
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--- a/drivers/md/dm.c
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+++ b/drivers/md/dm.c
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@@ -1729,7 +1729,8 @@ static int dm_merge_bvec(struct request_queue *q,
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struct mapped_device *md = q->queuedata;
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struct dm_table *map = dm_get_live_table_fast(md);
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struct dm_target *ti;
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- sector_t max_sectors, max_size = 0;
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+ sector_t max_sectors;
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+ int max_size = 0;
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if (unlikely(!map))
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goto out;
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@@ -1742,18 +1743,10 @@ static int dm_merge_bvec(struct request_queue *q,
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* Find maximum amount of I/O that won't need splitting
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*/
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max_sectors = min(max_io_len(bvm->bi_sector, ti),
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- (sector_t) queue_max_sectors(q));
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+ (sector_t) BIO_MAX_SECTORS);
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max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
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-
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- /*
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- * FIXME: this stop-gap fix _must_ be cleaned up (by passing a sector_t
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- * to the targets' merge function since it holds sectors not bytes).
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- * Just doing this as an interim fix for stable@ because the more
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- * comprehensive cleanup of switching to sector_t will impact every
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- * DM target that implements a ->merge hook.
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- */
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- if (max_size > INT_MAX)
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- max_size = INT_MAX;
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+ if (max_size < 0)
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+ max_size = 0;
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/*
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* merge_bvec_fn() returns number of bytes
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@@ -1761,13 +1754,13 @@ static int dm_merge_bvec(struct request_queue *q,
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* max is precomputed maximal io size
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*/
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if (max_size && ti->type->merge)
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- max_size = ti->type->merge(ti, bvm, biovec, (int) max_size);
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+ max_size = ti->type->merge(ti, bvm, biovec, max_size);
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/*
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* If the target doesn't support merge method and some of the devices
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- * provided their merge_bvec method (we know this by looking for the
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- * max_hw_sectors that dm_set_device_limits may set), then we can't
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- * allow bios with multiple vector entries. So always set max_size
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- * to 0, and the code below allows just one page.
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+ * provided their merge_bvec method (we know this by looking at
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+ * queue_max_hw_sectors), then we can't allow bios with multiple vector
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+ * entries. So always set max_size to 0, and the code below allows
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+ * just one page.
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*/
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else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9)
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max_size = 0;
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--
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2.4.3
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