Let the block device know when sectors can be discarded

[hirofumi@mail.parknet.co.jp: discard _after_ checking for corrupt chains]

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c
index 302e95c4af7e..fb98b3d847ed 100644
--- a/fs/fat/fatent.c
+++ b/fs/fat/fatent.c
@@ -6,6 +6,7 @@
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/msdos_fs.h>
+#include <linux/blkdev.h>
 
 struct fatent_operations {
         void (*ent_blocknr)(struct super_block *, int, int *, sector_t *);
@@ -535,6 +536,7 @@ int fat_free_clusters(struct inode *inode, int cluster)
         struct fat_entry fatent;
         struct buffer_head *bhs[MAX_BUF_PER_PAGE];
         int i, err, nr_bhs;
+        int first_cl = cluster;
 
         nr_bhs = 0;
         fatent_init(&fatent);
@@ -551,6 +553,18 @@ int fat_free_clusters(struct inode *inode, int cluster)
                         goto error;
                 }
 
+                /* 
+                 * Issue discard for the sectors we no longer care about,
+                 * batching contiguous clusters into one request
+                 */
+                if (cluster != fatent.entry + 1) {
+                        int nr_clus = fatent.entry - first_cl + 1;
+
+                        sb_issue_discard(sb, fat_clus_to_blknr(sbi, first_cl),
+                                         nr_clus * sbi->sec_per_clus);
+                        first_cl = cluster;
+                }
+
                 ops->ent_put(&fatent, FAT_ENT_FREE);
                 if (sbi->free_clusters != -1) {
                         sbi->free_clusters++;