1 files changed, 15 insertions, 6 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index c800d58f3013..7084140d5940 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -186,6 +186,7 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
                         split = alloc_extent_map(GFP_NOFS);
                 if (!split2)
                         split2 = alloc_extent_map(GFP_NOFS);
+                BUG_ON(!split || !split2);
 
                 write_lock(&em_tree->lock);
                 em = lookup_extent_mapping(em_tree, start, len);
@@ -793,8 +794,12 @@ again:
         for (i = 0; i < num_pages; i++) {
                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
                 if (!pages[i]) {
-                        err = -ENOMEM;
-                        BUG_ON(1);
+                        int c;
+                        for (c = i - 1; c >= 0; c--) {
+                                unlock_page(pages[c]);
+                                page_cache_release(pages[c]);
+                        }
+                        return -ENOMEM;
                 }
                 wait_on_page_writeback(pages[i]);
         }
@@ -946,6 +951,10 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
                      PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
                      (sizeof(struct page *)));
         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
+        if (!pages) {
+                ret = -ENOMEM;
+                goto out;
+        }
 
         /* generic_write_checks can change our pos */
         start_pos = pos;
@@ -984,8 +993,8 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
                 size_t write_bytes = min(iov_iter_count(&i),
                                          nrptrs * (size_t)PAGE_CACHE_SIZE -
                                          offset);
-                size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
-                                        PAGE_CACHE_SHIFT;
+                size_t num_pages = (write_bytes + offset +
+                                    PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 
                 WARN_ON(num_pages > nrptrs);
                 memset(pages, 0, sizeof(struct page *) * nrptrs);
@@ -1015,8 +1024,8 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
 
                 copied = btrfs_copy_from_user(pos, num_pages,
                                            write_bytes, pages, &i);
-                dirty_pages = (copied + PAGE_CACHE_SIZE - 1) >>
-                                        PAGE_CACHE_SHIFT;
+                dirty_pages = (copied + offset + PAGE_CACHE_SIZE - 1) >>
+                                PAGE_CACHE_SHIFT;
 
                 if (num_pages > dirty_pages) {
                         if (copied > 0)