brd: support discard

[safe/jmp/linux-2.6] / drivers / block / brd.c

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 24b97b0..f1bf79d 100644 (file)
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -15,9 +15,9 @@
 #include <linux/blkdev.h>
 #include <linux/bio.h>
 #include <linux/highmem.h>
-#include <linux/gfp.h>
 #include <linux/radix-tree.h>
 #include <linux/buffer_head.h> /* invalidate_bh_lrus() */
+#include <linux/slab.h>
 
 #include <asm/uaccess.h>
 
@@ -133,6 +133,28 @@ static struct page *brd_insert_page(struct brd_device *brd, sector_t sector)
        return page;
 }
 
+static void brd_free_page(struct brd_device *brd, sector_t sector)
+{
+       struct page *page;
+       pgoff_t idx;
+
+       spin_lock(&brd->brd_lock);
+       idx = sector >> PAGE_SECTORS_SHIFT;
+       page = radix_tree_delete(&brd->brd_pages, idx);
+       spin_unlock(&brd->brd_lock);
+       if (page)
+               __free_page(page);
+}
+
+static void brd_zero_page(struct brd_device *brd, sector_t sector)
+{
+       struct page *page;
+
+       page = brd_lookup_page(brd, sector);
+       if (page)
+               clear_highpage(page);
+}
+
 /*
  * Free all backing store pages and radix tree. This must only be called when
  * there are no other users of the device.
@@ -189,6 +211,24 @@ static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n)
        return 0;
 }
 
+static void discard_from_brd(struct brd_device *brd,
+                       sector_t sector, size_t n)
+{
+       while (n >= PAGE_SIZE) {
+               /*
+                * Don't want to actually discard pages here because
+                * re-allocating the pages can result in writeback
+                * deadlocks under heavy load.
+                */
+               if (0)
+                       brd_free_page(brd, sector);
+               else
+                       brd_zero_page(brd, sector);
+               sector += PAGE_SIZE >> SECTOR_SHIFT;
+               n -= PAGE_SIZE;
+       }
+}
+
 /*
  * Copy n bytes from src to the brd starting at sector. Does not sleep.
  */
@@ -275,8 +315,10 @@ static int brd_do_bvec(struct brd_device *brd, struct page *page,
        if (rw == READ) {
                copy_from_brd(mem + off, brd, sector, len);
                flush_dcache_page(page);
-       } else
+       } else {
+               flush_dcache_page(page);
                copy_to_brd(brd, mem + off, sector, len);
+       }
        kunmap_atomic(mem, KM_USER0);
 
 out:
@@ -298,6 +340,12 @@ static int brd_make_request(struct request_queue *q, struct bio *bio)
                                                get_capacity(bdev->bd_disk))
                goto out;
 
+       if (unlikely(bio_rw_flagged(bio, BIO_RW_DISCARD))) {
+               err = 0;
+               discard_from_brd(brd, sector, bio->bi_size);
+               goto out;
+       }
+
        rw = bio_rw(bio);
        if (rw == READA)
                rw = READ;
@@ -318,7 +366,7 @@ out:
 }
 
 #ifdef CONFIG_BLK_DEV_XIP
-static int brd_direct_access (struct block_device *bdev, sector_t sector,
+static int brd_direct_access(struct block_device *bdev, sector_t sector,
                        void **kaddr, unsigned long *pfn)
 {
        struct brd_device *brd = bdev->bd_disk->private_data;
@@ -340,11 +388,10 @@ static int brd_direct_access (struct block_device *bdev, sector_t sector,
 }
 #endif
 
-static int brd_ioctl(struct inode *inode, struct file *file,
+static int brd_ioctl(struct block_device *bdev, fmode_t mode,
                        unsigned int cmd, unsigned long arg)
 {
        int error;
-       struct block_device *bdev = inode->i_bdev;
        struct brd_device *brd = bdev->bd_disk->private_data;
 
        if (cmd != BLKFLSBUF)
@@ -374,9 +421,9 @@ static int brd_ioctl(struct inode *inode, struct file *file,
        return error;
 }
 
-static struct block_device_operations brd_fops = {
+static const struct block_device_operations brd_fops = {
        .owner =                THIS_MODULE,
-       .ioctl =                brd_ioctl,
+       .locked_ioctl =         brd_ioctl,
 #ifdef CONFIG_BLK_DEV_XIP
        .direct_access =        brd_direct_access,
 #endif
@@ -406,12 +453,7 @@ static int __init ramdisk_size(char *str)
        rd_size = simple_strtol(str, NULL, 0);
        return 1;
 }
-static int __init ramdisk_size2(char *str)
-{
-       return ramdisk_size(str);
-}
-__setup("ramdisk=", ramdisk_size);
-__setup("ramdisk_size=", ramdisk_size2);
+__setup("ramdisk_size=", ramdisk_size);
 #endif
 
 /*
@@ -437,9 +479,15 @@ static struct brd_device *brd_alloc(int i)
        if (!brd->brd_queue)
                goto out_free_dev;
        blk_queue_make_request(brd->brd_queue, brd_make_request);
-       blk_queue_max_sectors(brd->brd_queue, 1024);
+       blk_queue_ordered(brd->brd_queue, QUEUE_ORDERED_TAG, NULL);
+       blk_queue_max_hw_sectors(brd->brd_queue, 1024);
        blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY);
 
+       brd->brd_queue->limits.discard_granularity = PAGE_SIZE;
+       brd->brd_queue->limits.max_discard_sectors = UINT_MAX;
+       brd->brd_queue->limits.discard_zeroes_data = 1;
+       queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, brd->brd_queue);
+
        disk = brd->brd_disk = alloc_disk(1 << part_shift);
        if (!disk)
                goto out_free_queue;
@@ -571,8 +619,8 @@ out_free:
                list_del(&brd->brd_list);
                brd_free(brd);
        }
+       unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
 
-       unregister_blkdev(RAMDISK_MAJOR, "brd");
        return -ENOMEM;
 }