Btrfs: use the inode's mapping mask for allocating pages

Johannes pointed out we were allocating only kernel pages for doing writes,
which is kind of a big deal if you are on 32bit and have more than a gig of ram.
So fix our allocations to use the mapping's gfp but still clear __GFP_FS so we
don't re-enter.  Thanks,

Reported-by: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Josef Bacik <josef@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index de569af766fe..f2e928289600 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1069,6 +1069,7 @@ static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
         int i;
         unsigned long index = pos >> PAGE_CACHE_SHIFT;
         struct inode *inode = fdentry(file)->d_inode;
+        gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
         int err = 0;
         int faili = 0;
         u64 start_pos;
@@ -1080,7 +1081,7 @@ static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
 again:
         for (i = 0; i < num_pages; i++) {
                 pages[i] = find_or_create_page(inode->i_mapping, index + i,
-                                               GFP_NOFS);
+                                               mask);
                 if (!pages[i]) {
                         faili = i - 1;
                         err = -ENOMEM;