Bug fix: Fix FITRIM argument handling

-----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2.0.19 (GNU/Linux)
 
 iQIcBAABAgAGBQJQhZDSAAoJEDaohF61QIxkwgkP/0j/ygUXo50k7EkdwFsC0mHw
 lQ5iirP7oUJ1p1v2PeaBqBulql5yseqTj6keLTTrYSBG/Ocp8qir9z0pyqWjN112
 DU8o/CPSVXnAj64d7Nu/YZBGdUHWQu+1Wex+nDyh2QXdJx94G3SoE3ZZ86BiXJ01
 1rVvHB+FuyzbKFCEk8hslKyJ8WHv1flu+9ulxQXDATrxJxqqTvBkRdT21h3Ds+d8
 HQhxj2RHT7yVHWvyQumTNLLVWOtuT+Svd3Mglzl4bbfAQ49THJFHaxGp1ufGZlR/
 iZ2+yoTU9ze+2JZ8FuCCkSfhv55iugLS8FRHUT6VdErOKnHum4aZgkHCz3oA0c5B
 FI/8pVUqEkf3wENxaM96O+XEIxF4ChMeF+fm3niMb0nL3Fiv7Sx97XExTqMhVhlv
 Xn+t71oNaU2xhus2A9Nd95oGEg9qQ2L0fvDWDV7/p+PvRRkCd0oKBVILZhVCMJ/V
 hvhbhNObUNWAb8x1pmrgWyk2H+dn4tX5SbyrbxnEAmX3oifw7CCfmZGDF+nanmMt
 cnqIjQ3qZxvQ/io6Edye0NX21K0HQcS2Bdh09uuWT+C3UNjwqGceyZdeay2gdWpP
 R7DgiaSm7+590InRweuREttVFigzOVDhN3zZTwlPGLUZ3q9EwdOcnhrPMD8ThT48
 mVWzYaPwGax3Ro3IjWsJ
 =M5iC
 -----END PGP SIGNATURE-----

Merge tag 'jfs-3.7-2' of git://github.com/kleikamp/linux-shaggy

Pull jfs fix from Dave Kleikamp:
 "Bug fix: Fix FITRIM argument handling"

* tag 'jfs-3.7-2' of git://github.com/kleikamp/linux-shaggy:
  jfs: Fix FITRIM argument handling

fs/jfs/jfs_discard.c

@@ -83,7 +83,7 @@ int jfs_ioc_trim(struct inode *ip, struct fstrim_range *range)
 	struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
 	struct super_block *sb = ipbmap->i_sb;
 	int agno, agno_end;
-	s64 start, end, minlen;
+	u64 start, end, minlen;
 	u64 trimmed = 0;
 
 	/**
@@ -93,14 +93,18 @@ int jfs_ioc_trim(struct inode *ip, struct fstrim_range *range)
 	 * minlen:	minimum extent length in Bytes
 	 */
 	start = range->start >> sb->s_blocksize_bits;
-	if (start < 0)
-		start = 0;
 	end = start + (range->len >> sb->s_blocksize_bits) - 1;
+	minlen = range->minlen >> sb->s_blocksize_bits;
+	if (minlen == 0)
+		minlen = 1;
+
+	if (minlen > bmp->db_agsize ||
+	    start >= bmp->db_mapsize ||
+	    range->len < sb->s_blocksize)
+		return -EINVAL;
+
 	if (end >= bmp->db_mapsize)
 		end = bmp->db_mapsize - 1;
-	minlen = range->minlen >> sb->s_blocksize_bits;
-	if (minlen <= 0)
-		minlen = 1;
 
 	/**
 	 * we trim all ag's within the range