btrfs: use kvzalloc for EXTENT_SAME temporary data

The dedupe range is 16 MiB, with 4 KiB pages and 8 byte pointers, the
arrays can be 32KiB large. To avoid allocation failures due to
fragmented memory, use the allocation with fallback to vmalloc.

The arrays are allocated and freed only inside btrfs_extent_same and
reused for all the ranges.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 99eab7b3e5e1ab3601b30ef4d9debcf299c9ff23..aeef6cd8aaeb242feba6b409582d97b11ac83c0e 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3144,12 +3144,13 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
         * locking. We use an array for the page pointers. Size of the array is
         * bounded by len, which is in turn bounded by BTRFS_MAX_DEDUPE_LEN.
         */
-       cmp.src_pages = kcalloc(num_pages, sizeof(struct page *), GFP_KERNEL);
-       cmp.dst_pages = kcalloc(num_pages, sizeof(struct page *), GFP_KERNEL);
+       cmp.src_pages = kvmalloc_array(num_pages, sizeof(struct page *),
+                                      GFP_KERNEL | __GFP_ZERO);
+       cmp.dst_pages = kvmalloc_array(num_pages, sizeof(struct page *),
+                                      GFP_KERNEL | __GFP_ZERO);
        if (!cmp.src_pages || !cmp.dst_pages) {
-               kfree(cmp.src_pages);
-               kfree(cmp.dst_pages);
-               return -ENOMEM;
+               ret = -ENOMEM;
+               goto out_free;
        }
 
        for (i = 0; i < chunk_count; i++) {
@@ -3172,8 +3173,9 @@ out_unlock:
        else
                btrfs_double_inode_unlock(src, dst);
 
-       kfree(cmp.src_pages);
-       kfree(cmp.dst_pages);
+out_free:
+       kvfree(cmp.src_pages);
+       kvfree(cmp.dst_pages);
 
        return ret;
 }