[PATCH] md: define and use safe_put_page for md

md sometimes call put_page on NULL pointers (treating it like kfree).  This is
not safe, so define and use a 'safe_put_page' which checks for NULL.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 10 insertions, 12 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index abe415f0c039..ee4a3424a8a3 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -626,8 +626,7 @@ static void bitmap_file_unmap(struct bitmap *bitmap)
         kfree(map);
         kfree(attr);
 
-        if (sb_page)
-                put_page(sb_page);
+        safe_put_page(sb_page);
 }
 
 static void bitmap_stop_daemon(struct bitmap *bitmap);
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 39c10a65683d..feea4eeca1d9 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -136,7 +136,7 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
 out_free_pages:
         for (i=0; i < RESYNC_PAGES ; i++)
                 for (j=0 ; j < pi->raid_disks; j++)
-                        put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
+                        safe_put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
         j = -1;
 out_free_bio:
         while ( ++j < pi->raid_disks )
@@ -156,7 +156,7 @@ static void r1buf_pool_free(void *__r1_bio, void *data)
                         if (j == 0 ||
                             r1bio->bios[j]->bi_io_vec[i].bv_page !=
                             r1bio->bios[0]->bi_io_vec[i].bv_page)
-                                put_page(r1bio->bios[j]->bi_io_vec[i].bv_page);
+                                safe_put_page(r1bio->bios[j]->bi_io_vec[i].bv_page);
                 }
         for (i=0 ; i < pi->raid_disks; i++)
                 bio_put(r1bio->bios[i]);
@@ -381,7 +381,7 @@ static int raid1_end_write_request(struct bio *bio, unsigned int bytes_done, int
                         /* free extra copy of the data pages */
                         int i = bio->bi_vcnt;
                         while (i--)
-                                put_page(bio->bi_io_vec[i].bv_page);
+                                safe_put_page(bio->bi_io_vec[i].bv_page);
                 }
                 /* clear the bitmap if all writes complete successfully */
                 bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
@@ -1907,7 +1907,7 @@ out_free_conf:
                 if (conf->r1bio_pool)
                         mempool_destroy(conf->r1bio_pool);
                 kfree(conf->mirrors);
-                put_page(conf->tmppage);
+                safe_put_page(conf->tmppage);
                 kfree(conf->poolinfo);
                 kfree(conf);
                 mddev->private = NULL;
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 9647ebb0983a..fb952000fae2 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -132,10 +132,10 @@ static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
 
 out_free_pages:
         for ( ; i > 0 ; i--)
-                put_page(bio->bi_io_vec[i-1].bv_page);
+                safe_put_page(bio->bi_io_vec[i-1].bv_page);
         while (j--)
                 for (i = 0; i < RESYNC_PAGES ; i++)
-                        put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
+                        safe_put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
         j = -1;
 out_free_bio:
         while ( ++j < nalloc )
@@ -155,7 +155,7 @@ static void r10buf_pool_free(void *__r10_bio, void *data)
                 struct bio *bio = r10bio->devs[j].bio;
                 if (bio) {
                         for (i = 0; i < RESYNC_PAGES; i++) {
-                                put_page(bio->bi_io_vec[i].bv_page);
+                                safe_put_page(bio->bi_io_vec[i].bv_page);
                                 bio->bi_io_vec[i].bv_page = NULL;
                         }
                         bio_put(bio);
@@ -2042,7 +2042,7 @@ static int run(mddev_t *mddev)
 out_free_conf:
         if (conf->r10bio_pool)
                 mempool_destroy(conf->r10bio_pool);
-        put_page(conf->tmppage);
+        safe_put_page(conf->tmppage);
         kfree(conf->mirrors);
         kfree(conf);
         mddev->private = NULL;
diff --git a/drivers/md/raid6main.c b/drivers/md/raid6main.c
index 950e5fa6e1f2..06b32bd671a3 100644
--- a/drivers/md/raid6main.c
+++ b/drivers/md/raid6main.c
@@ -2072,8 +2072,7 @@ static int run(mddev_t *mddev)
 abort:
         if (conf) {
                 print_raid6_conf(conf);
-                if (conf->spare_page)
-                        put_page(conf->spare_page);
+                safe_put_page(conf->spare_page);
                 kfree(conf->stripe_hashtbl);
                 kfree(conf);
         }