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dm: make dm_table_find_target return NULL

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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@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka 2019-08-23 09:55:26 -04:00 committed by Mike Snitzer
parent 1cfd5d3399
commit 123d87d553
4 changed files with 8 additions and 15 deletions
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2
drivers/md/dm-ioctl.c
View File

@ -1592,7 +1592,7 @@ static int target_message(struct file *filp, struct dm_ioctl *param, size_t para
}
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)

8
drivers/md/dm-table.c
View File

@ -163,10 +163,8 @@ static int alloc_targets(struct dm_table *t, unsigned int num)
/*
* 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(struct dm_table *t, unsigned int index)
/*
* 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(struct dm_table *t, sector_t sector)
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);

8
drivers/md/dm.c
View File

@ -457,7 +457,7 @@ static int dm_blk_report_zones(struct gendisk *disk, sector_t sector,
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_target(struct mapped_device *md,
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(struct clone_info *ci)
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 mapped_device *md,
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;
}

5
drivers/md/dm.h
View File

@ -85,11 +85,6 @@ struct target_type *dm_get_immutable_target_type(struct mapped_device *md);
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).
*/