1 files changed, 18 insertions, 6 deletions

diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index a177eae3aa1a..addd7c5f2d3e 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -7304,13 +7304,24 @@ out:
 
 static int ocfs2_trim_extent(struct super_block *sb,
                              struct ocfs2_group_desc *gd,
-                             u32 start, u32 count)
+                             u64 group, u32 start, u32 count)
 {
         u64 discard, bcount;
+        struct ocfs2_super *osb = OCFS2_SB(sb);
 
         bcount = ocfs2_clusters_to_blocks(sb, count);
-        discard = le64_to_cpu(gd->bg_blkno) +
-                        ocfs2_clusters_to_blocks(sb, start);
+        discard = ocfs2_clusters_to_blocks(sb, start);
+
+        /*
+         * For the first cluster group, the gd->bg_blkno is not at the start
+         * of the group, but at an offset from the start. If we add it while
+         * calculating discard for first group, we will wrongly start fstrim a
+         * few blocks after the desried start block and the range can cross
+         * over into the next cluster group. So, add it only if this is not
+         * the first cluster group.
+         */
+        if (group != osb->first_cluster_group_blkno)
+                discard += le64_to_cpu(gd->bg_blkno);
 
         trace_ocfs2_trim_extent(sb, (unsigned long long)discard, bcount);
 
@@ -7318,7 +7329,7 @@ static int ocfs2_trim_extent(struct super_block *sb,
 }
 
 static int ocfs2_trim_group(struct super_block *sb,
-                            struct ocfs2_group_desc *gd,
+                            struct ocfs2_group_desc *gd, u64 group,
                             u32 start, u32 max, u32 minbits)
 {
         int ret = 0, count = 0, next;
@@ -7337,7 +7348,7 @@ static int ocfs2_trim_group(struct super_block *sb,
                 next = ocfs2_find_next_bit(bitmap, max, start);
 
                 if ((next - start) >= minbits) {
-                        ret = ocfs2_trim_extent(sb, gd,
+                        ret = ocfs2_trim_extent(sb, gd, group,
                                                 start, next - start);
                         if (ret < 0) {
                                 mlog_errno(ret);
@@ -7435,7 +7446,8 @@ int ocfs2_trim_fs(struct super_block *sb, struct fstrim_range *range)
                 }
 
                 gd = (struct ocfs2_group_desc *)gd_bh->b_data;
-                cnt = ocfs2_trim_group(sb, gd, first_bit, last_bit, minlen);
+                cnt = ocfs2_trim_group(sb, gd, group,
+                                       first_bit, last_bit, minlen);
                 brelse(gd_bh);
                 gd_bh = NULL;
                 if (cnt < 0) {