pnfs/blocklayout: Ensure disk address in block device map
diff mbox

Message ID 8d0b4d04a683809e9986396840abcba1f5110dff.1516805178.git.bcodding@redhat.com
State New
Headers show

Commit Message

Benjamin Coddington Jan. 24, 2018, 2:48 p.m. UTC
It's possible that the device map is smaller than the offset into the
device for the I/O we're adding.  This probably indicates an error of some
sort (such as the dev->len = 0 due to the device being unreadable), so
let's add a check for it and bail out.  Otherwise, we risk botching the bio
calculations that follow.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
---
 fs/nfs/blocklayout/blocklayout.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Comments

Trond Myklebust Jan. 24, 2018, 11:08 p.m. UTC | #1
On Wed, 2018-01-24 at 09:48 -0500, Benjamin Coddington wrote:
> It's possible that the device map is smaller than the offset into the
> device for the I/O we're adding.  This probably indicates an error of
> some
> sort (such as the dev->len = 0 due to the device being unreadable),
> so
> let's add a check for it and bail out.  Otherwise, we risk botching
> the bio
> calculations that follow.
> 
> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
> ---
>  fs/nfs/blocklayout/blocklayout.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/nfs/blocklayout/blocklayout.c
> b/fs/nfs/blocklayout/blocklayout.c
> index 334570888649..6259ef20ee3e 100644
> --- a/fs/nfs/blocklayout/blocklayout.c
> +++ b/fs/nfs/blocklayout/blocklayout.c
> @@ -137,6 +137,11 @@ bl_alloc_init_bio(int npg, struct block_device
> *bdev, sector_t disk_sector,
>  	return bio;
>  }
>  
> +static bool offset_in_map(sector_t isect, struct pnfs_block_dev_map
> *map)
> +{
> +	return isect >= map->start && isect < map->start + map->len;
> +}
> +
>  static struct bio *
>  do_add_page_to_bio(struct bio *bio, int npg, int rw, sector_t isect,
>  		struct page *page, struct pnfs_block_dev_map *map,
> @@ -156,8 +161,8 @@ do_add_page_to_bio(struct bio *bio, int npg, int
> rw, sector_t isect,
>  
>  	/* translate to physical disk offset */
>  	disk_addr = (u64)isect << SECTOR_SHIFT;
> -	if (disk_addr < map->start || disk_addr >= map->start + map-
> >len) {
> -		if (!dev->map(dev, disk_addr, map))
> +	if (!offset_in_map(isect, map)) {
> +		if (!dev->map(dev, disk_addr, map) ||
> !offset_in_map(isect, map))
>  			return ERR_PTR(-EIO);
>  		bio = bl_submit_bio(bio);
>  	}

I'm confused. While your patch does appear to make sense, there is
other code in the same function that mixes type sector_t and disk
offsets (including a line of the form 'disk_addr -= map->start').

IOW: if this patch makes sense, then there is definitely more code to
fix in the same function.
Benjamin Coddington Jan. 25, 2018, 12:52 p.m. UTC | #2
On 24 Jan 2018, at 18:08, Trond Myklebust wrote:

> On Wed, 2018-01-24 at 09:48 -0500, Benjamin Coddington wrote:
>> It's possible that the device map is smaller than the offset into the
>> device for the I/O we're adding.  This probably indicates an error of
>> some
>> sort (such as the dev->len = 0 due to the device being unreadable),
>> so
>> let's add a check for it and bail out.  Otherwise, we risk botching
>> the bio
>> calculations that follow.
>>
>> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
>> ---
>>  fs/nfs/blocklayout/blocklayout.c | 9 +++++++--
>>  1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/nfs/blocklayout/blocklayout.c
>> b/fs/nfs/blocklayout/blocklayout.c
>> index 334570888649..6259ef20ee3e 100644
>> --- a/fs/nfs/blocklayout/blocklayout.c
>> +++ b/fs/nfs/blocklayout/blocklayout.c
>> @@ -137,6 +137,11 @@ bl_alloc_init_bio(int npg, struct block_device
>> *bdev, sector_t disk_sector,
>>  	return bio;
>>  }
>>
>> +static bool offset_in_map(sector_t isect, struct pnfs_block_dev_map
>> *map)
>> +{
>> +	return isect >= map->start && isect < map->start + map->len;
>> +}
>> +
>>  static struct bio *
>>  do_add_page_to_bio(struct bio *bio, int npg, int rw, sector_t isect,
>>  		struct page *page, struct pnfs_block_dev_map *map,
>> @@ -156,8 +161,8 @@ do_add_page_to_bio(struct bio *bio, int npg, int
>> rw, sector_t isect,
>>
>>  	/* translate to physical disk offset */
>>  	disk_addr = (u64)isect << SECTOR_SHIFT;
>> -	if (disk_addr < map->start || disk_addr >= map->start + map-
>>> len) {
>> -		if (!dev->map(dev, disk_addr, map))
>> +	if (!offset_in_map(isect, map)) {
>> +		if (!dev->map(dev, disk_addr, map) ||
>> !offset_in_map(isect, map))
>>  			return ERR_PTR(-EIO);
>>  		bio = bl_submit_bio(bio);
>>  	}
>
> I'm confused. While your patch does appear to make sense, there is
> other code in the same function that mixes type sector_t and disk
> offsets (including a line of the form 'disk_addr -= map->start').
>
> IOW: if this patch makes sense, then there is definitely more code to
> fix in the same function.

Yes, this is wrong.  I think struct pnfs_block_dev_map should be byte
offsets not sectors.  I'll send a patch for that, and then this one again.

Ben
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Patch
diff mbox

diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 334570888649..6259ef20ee3e 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -137,6 +137,11 @@  bl_alloc_init_bio(int npg, struct block_device *bdev, sector_t disk_sector,
 	return bio;
 }
 
+static bool offset_in_map(sector_t isect, struct pnfs_block_dev_map *map)
+{
+	return isect >= map->start && isect < map->start + map->len;
+}
+
 static struct bio *
 do_add_page_to_bio(struct bio *bio, int npg, int rw, sector_t isect,
 		struct page *page, struct pnfs_block_dev_map *map,
@@ -156,8 +161,8 @@  do_add_page_to_bio(struct bio *bio, int npg, int rw, sector_t isect,
 
 	/* translate to physical disk offset */
 	disk_addr = (u64)isect << SECTOR_SHIFT;
-	if (disk_addr < map->start || disk_addr >= map->start + map->len) {
-		if (!dev->map(dev, disk_addr, map))
+	if (!offset_in_map(isect, map)) {
+		if (!dev->map(dev, disk_addr, map) || !offset_in_map(isect, map))
 			return ERR_PTR(-EIO);
 		bio = bl_submit_bio(bio);
 	}