dm: fix improper splitting for abnormal bios

jira LE-1907
Rebuild_History Non-Buildable kernel-rt-5.14.0-284.30.1.rt14.315.el9_2
commit-author Mike Snitzer <[email protected]>
commit f7b58a6
Empty-Commit: Cherry-Pick Conflicts during history rebuild.
Will be included in final tarball splat. Ref for failed cherry-pick at:
ciq/ciq_backports/kernel-rt-5.14.0-284.30.1.rt14.315.el9_2/f7b58a69.failed

"Abnormal" bios include discards, write zeroes and secure erase. By no
longer passing the calculated 'len' pointer, commit 7dd06a2 ("dm:
allow dm_accept_partial_bio() for dm_io without duplicate bios") took a
senseless approach to disallowing dm_accept_partial_bio() from working
for duplicate bios processed using __send_duplicate_bios().

It inadvertently and incorrectly stopped the use of 'len' when
initializing a target's io (in alloc_tio). As such the resulting tio
could address more area of a device than it should.

For example, when discarding an entire DM striped device with the
following DM table:
 vg-lvol0: 0 159744 striped 2 128 7:0 2048 7:1 2048
 vg-lvol0: 159744 45056 striped 2 128 7:2 2048 7:3 2048

Before this fix:

 device-mapper: striped: target_stripe=0, bdev=7:0, start=2048 len=102400
 blkdiscard: attempt to access beyond end of device
 loop0: rw=2051, sector=2048, nr_sectors = 102400 limit=81920

 device-mapper: striped: target_stripe=1, bdev=7:1, start=2048 len=102400
 blkdiscard: attempt to access beyond end of device
 loop1: rw=2051, sector=2048, nr_sectors = 102400 limit=81920

After this fix;

 device-mapper: striped: target_stripe=0, bdev=7:0, start=2048 len=79872
 device-mapper: striped: target_stripe=1, bdev=7:1, start=2048 len=79872

Fixes: 7dd06a2 ("dm: allow dm_accept_partial_bio() for dm_io without duplicate bios")
	Cc: [email protected]
	Reported-by: Orange Kao <[email protected]>
	Signed-off-by: Mike Snitzer <[email protected]>
(cherry picked from commit f7b58a6)
	Signed-off-by: Jonathan Maple <[email protected]>

# Conflicts:
#	drivers/md/dm.c

Author: PlaidCat

ciq/ciq_backports/kernel-rt-5.14.0-284.30.1.rt14.315.el9_2/f7b58a69.failed

@@ -0,0 +1,67 @@
+dm: fix improper splitting for abnormal bios
+
+jira LE-1907
+Rebuild_History Non-Buildable kernel-rt-5.14.0-284.30.1.rt14.315.el9_2
+commit-author Mike Snitzer <[email protected]>
+commit f7b58a69fad9d2c4c90cab0247811155dd0d48e7
+Empty-Commit: Cherry-Pick Conflicts during history rebuild.
+Will be included in final tarball splat. Ref for failed cherry-pick at:
+ciq/ciq_backports/kernel-rt-5.14.0-284.30.1.rt14.315.el9_2/f7b58a69.failed
+
+"Abnormal" bios include discards, write zeroes and secure erase. By no
+longer passing the calculated 'len' pointer, commit 7dd06a2548b2 ("dm:
+allow dm_accept_partial_bio() for dm_io without duplicate bios") took a
+senseless approach to disallowing dm_accept_partial_bio() from working
+for duplicate bios processed using __send_duplicate_bios().
+
+It inadvertently and incorrectly stopped the use of 'len' when
+initializing a target's io (in alloc_tio). As such the resulting tio
+could address more area of a device than it should.
+
+For example, when discarding an entire DM striped device with the
+following DM table:
+ vg-lvol0: 0 159744 striped 2 128 7:0 2048 7:1 2048
+ vg-lvol0: 159744 45056 striped 2 128 7:2 2048 7:3 2048
+
+Before this fix:
+
+ device-mapper: striped: target_stripe=0, bdev=7:0, start=2048 len=102400
+ blkdiscard: attempt to access beyond end of device
+ loop0: rw=2051, sector=2048, nr_sectors = 102400 limit=81920
+
+ device-mapper: striped: target_stripe=1, bdev=7:1, start=2048 len=102400
+ blkdiscard: attempt to access beyond end of device
+ loop1: rw=2051, sector=2048, nr_sectors = 102400 limit=81920
+
+After this fix;
+
+ device-mapper: striped: target_stripe=0, bdev=7:0, start=2048 len=79872
+ device-mapper: striped: target_stripe=1, bdev=7:1, start=2048 len=79872
+
+Fixes: 7dd06a2548b2 ("dm: allow dm_accept_partial_bio() for dm_io without duplicate bios")
+	Cc: [email protected]
+	Reported-by: Orange Kao <[email protected]>
+	Signed-off-by: Mike Snitzer <[email protected]>
+(cherry picked from commit f7b58a69fad9d2c4c90cab0247811155dd0d48e7)
+	Signed-off-by: Jonathan Maple <[email protected]>
+
+# Conflicts:
+#	drivers/md/dm.c
+diff --cc drivers/md/dm.c
+index a84025b34305,e67a2757c53e..000000000000
+--- a/drivers/md/dm.c
++++ b/drivers/md/dm.c
+@@@ -1524,7 -1467,8 +1524,12 @@@ static void setup_split_accounting(stru
+  }
+  
+  static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci,
+++<<<<<<< HEAD
+ +				struct dm_target *ti, unsigned num_bios)
+++=======
++ 				struct dm_target *ti, unsigned int num_bios,
++ 				unsigned *len)
+++>>>>>>> f7b58a69fad9 (dm: fix improper splitting for abnormal bios)
+  {
+  	struct bio *bio;
+  	int try;
+* Unmerged path drivers/md/dm.c