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Message-ID: <alpine.LRH.2.02.1908230954190.22174@file01.intranet.prod.int.rdu2.redhat.com>
Date: Fri, 23 Aug 2019 09:55:26 -0400 (EDT)
From: Mikulas Patocka <mpatocka@...hat.com>
To: Zhang Tao <kontais@...o.com>
cc: agk@...hat.com, snitzer@...hat.com,
Zhang Tao <zhangtao27@...ovo.com>, dm-devel@...hat.com,
linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] dm: make dm_table_find_target return NULL
Currently, if we pass too high sector number to dm_table_find_target, it
returns zeroed dm_target structure and callers test if the structure is
zeroed with the macro dm_target_is_valid.
However, returning NULL is common practice to indicate errors.
This patch refactors the dm code, so that dm_table_find_target returns
NULL and its callers test the returned value for NULL. The macro
dm_target_is_valid is deleted. In alloc_targets, we no longer allocate an
extra zeroed target.
Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
---
drivers/md/dm-ioctl.c | 2 +-
drivers/md/dm-table.c | 8 +++-----
drivers/md/dm.c | 8 ++++----
drivers/md/dm.h | 5 -----
4 files changed, 8 insertions(+), 15 deletions(-)
Index: linux-2.6/drivers/md/dm.c
===================================================================
--- linux-2.6.orig/drivers/md/dm.c 2019-08-23 15:45:46.000000000 +0200
+++ linux-2.6/drivers/md/dm.c 2019-08-23 15:45:46.000000000 +0200
@@ -457,7 +457,7 @@ static int dm_blk_report_zones(struct ge
return -EIO;
tgt = dm_table_find_target(map, sector);
- if (!dm_target_is_valid(tgt)) {
+ if (!tgt) {
ret = -EIO;
goto out;
}
@@ -1072,7 +1072,7 @@ static struct dm_target *dm_dax_get_live
return NULL;
ti = dm_table_find_target(map, sector);
- if (!dm_target_is_valid(ti))
+ if (!ti)
return NULL;
return ti;
@@ -1572,7 +1572,7 @@ static int __split_and_process_non_flush
int r;
ti = dm_table_find_target(ci->map, ci->sector);
- if (!dm_target_is_valid(ti))
+ if (!ti)
return -EIO;
if (__process_abnormal_io(ci, ti, &r))
@@ -1748,7 +1748,7 @@ static blk_qc_t dm_process_bio(struct ma
if (!ti) {
ti = dm_table_find_target(map, bio->bi_iter.bi_sector);
- if (unlikely(!ti || !dm_target_is_valid(ti))) {
+ if (unlikely(!ti)) {
bio_io_error(bio);
return ret;
}
Index: linux-2.6/drivers/md/dm-ioctl.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-ioctl.c 2019-08-23 15:45:46.000000000 +0200
+++ linux-2.6/drivers/md/dm-ioctl.c 2019-08-23 15:45:46.000000000 +0200
@@ -1592,7 +1592,7 @@ static int target_message(struct file *f
}
ti = dm_table_find_target(table, tmsg->sector);
- if (!dm_target_is_valid(ti)) {
+ if (!ti) {
DMWARN("Target message sector outside device.");
r = -EINVAL;
} else if (ti->type->message)
Index: linux-2.6/drivers/md/dm-table.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-table.c 2019-08-23 15:45:46.000000000 +0200
+++ linux-2.6/drivers/md/dm-table.c 2019-08-23 15:47:18.000000000 +0200
@@ -163,10 +163,8 @@ static int alloc_targets(struct dm_table
/*
* Allocate both the target array and offset array at once.
- * Append an empty entry to catch sectors beyond the end of
- * the device.
*/
- n_highs = (sector_t *) dm_vcalloc(num + 1, sizeof(struct dm_target) +
+ n_highs = (sector_t *) dm_vcalloc(num, sizeof(struct dm_target) +
sizeof(sector_t));
if (!n_highs)
return -ENOMEM;
@@ -1359,7 +1357,7 @@ struct dm_target *dm_table_get_target(st
/*
* Search the btree for the correct target.
*
- * Caller should check returned pointer with dm_target_is_valid()
+ * Caller should check returned pointer for NULL
* to trap I/O beyond end of device.
*/
struct dm_target *dm_table_find_target(struct dm_table *t, sector_t sector)
@@ -1368,7 +1366,7 @@ struct dm_target *dm_table_find_target(s
sector_t *node;
if (unlikely(sector >= dm_table_get_size(t)))
- return &t->targets[t->num_targets];
+ return NULL;
for (l = 0; l < t->depth; l++) {
n = get_child(n, k);
Index: linux-2.6/drivers/md/dm.h
===================================================================
--- linux-2.6.orig/drivers/md/dm.h 2019-08-23 15:45:46.000000000 +0200
+++ linux-2.6/drivers/md/dm.h 2019-08-23 15:45:46.000000000 +0200
@@ -86,11 +86,6 @@ struct target_type *dm_get_immutable_tar
int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t);
/*
- * To check the return value from dm_table_find_target().
- */
-#define dm_target_is_valid(t) ((t)->table)
-
-/*
* To check whether the target type is bio-based or not (request-based).
*/
#define dm_target_bio_based(t) ((t)->type->map != NULL)
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