Re: [Jfs-discussion] fs/jfs: TRIM support for JFS Filesystem

[Dave K. <dav...@or...>]

On 09/18/2012 01:57 AM, Dan Carpenter wrote:
> Hello Tino Reichardt,
> 
> The patch 0d59722ea777: "fs/jfs: TRIM support for JFS Filesystem"
> from Aug 29, 2012, leads to the following static checker warning:
> fs/jfs/jfs_dmap.c:1650 dbDiscardAG()
> 	 warn: check 'range_cnt' for negative values
> 
>   1648          nblocks = bmp->db_agfree[agno];
>   1649          range_cnt = min_t(int, range_cnt, nblocks / minlen + 1);
>                                   ^^^
> Could we make this unsigned?  The caller checks that minlen is >= 1 and
> probably someone checks nblocks as well, but it's annoying to have to
> audit this.

Dan, the following patch applies on top of the Sept. 18 linux-next
build or git://github.com/kleikamp/linux-shaggy.git jfs-next

> 
>   1650          totrim = kmalloc(sizeof(struct range2trim) * range_cnt, GFP_NOFS);
>   1651          if (totrim == NULL) {
>   1652                  jfs_error(bmp->db_ipbmap->i_sb,
>   1653                            "dbDiscardAG: no memory for trim array");
>   1654                  IWRITE_UNLOCK(ipbmap);
>   1655                  return 0;
>   1656          }
> 
> regards,
> dan carpenter

jfs: Fix do_div precision in commit b40c2e66

In a hasty fix to replace a 64-bit division with do_div, I
unintentionally assigned the divisor to a 32-bit variable.

Signed-off-by: Dave Kleikamp <dav...@or...>
Cc: Tino Reichardt <mil...@mc...>
---
 fs/jfs/jfs_dmap.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index 174feb6..9a55f53 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -1641,14 +1641,15 @@ s64 dbDiscardAG(struct inode *ip, int agno, s64 minlen)
 
 	/* max blkno / nblocks pairs to trim */
 	int count = 0, range_cnt;
+	u64 max_ranges;
 
 	/* prevent others from writing new stuff here, while trimming */
 	IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
 
 	nblocks = bmp->db_agfree[agno];
-	range_cnt = nblocks;
-	do_div(range_cnt, (int)minlen);
-	range_cnt = min(range_cnt + 1, 32 * 1024);
+	max_ranges = nblocks;
+	do_div(max_ranges, minlen);
+	range_cnt = min_t(u64, max_ranges + 1, 32 * 1024);
 	totrim = kmalloc(sizeof(struct range2trim) * range_cnt, GFP_NOFS);
 	if (totrim == NULL) {
 		jfs_error(bmp->db_ipbmap->i_sb,
-- 
1.7.12