ext4: Don't look at buffer_heads outside i_size.

Buffer heads outside i_size will be unmapped. So when we
are doing "walk_page_buffers" limit ourself to i_size.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: Josef Bacik <jbacik@redhat.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
----

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ff2afc1..b87b68c 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2578,7 +2578,7 @@ static int ext4_da_writepage(struct page *page,
                 * all are mapped and non delay. We don't want to
                 * do block allocation here.
                 */
-               ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
+               ret = block_prepare_write(page, 0, len,
                                          noalloc_get_block_write);
                if (!ret) {
                        page_bufs = page_buffers(page);
@@ -2600,7 +2600,7 @@ static int ext4_da_writepage(struct page *page,
                        return 0;
                }
                /* now mark the buffer_heads as dirty and uptodate */
-               block_commit_write(page, 0, PAGE_CACHE_SIZE);
+               block_commit_write(page, 0, len);
        }
 
        if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
@@ -3246,6 +3246,8 @@ static int ext4_normal_writepage(struct page *page,
 static int __ext4_journalled_writepage(struct page *page,
                                       struct writeback_control *wbc)
 {
+       loff_t size;
+       unsigned int len;
        struct address_space *mapping = page->mapping;
        struct inode *inode = mapping->host;
        struct buffer_head *page_bufs;
@@ -3253,14 +3255,17 @@ static int __ext4_journalled_writepage(struct page *page,
        int ret = 0;
        int err;
 
-       ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
-                                 noalloc_get_block_write);
+       size = i_size_read(inode);
+       if (page->index == size >> PAGE_CACHE_SHIFT)
+               len = size & ~PAGE_CACHE_MASK;
+       else
+               len = PAGE_CACHE_SIZE;
+       ret = block_prepare_write(page, 0, len, noalloc_get_block_write);
        if (ret != 0)
                goto out_unlock;
 
        page_bufs = page_buffers(page);
-       walk_page_buffers(handle, page_bufs, 0, PAGE_CACHE_SIZE, NULL,
-                                                               bget_one);
+       walk_page_buffers(handle, page_bufs, 0, len, NULL, bget_one);
        /* As soon as we unlock the page, it can go away, but we have
         * references to buffers so we are safe */
        unlock_page(page);
@@ -3271,19 +3276,18 @@ static int __ext4_journalled_writepage(struct page *page,
                goto out;
        }
 
-       ret = walk_page_buffers(handle, page_bufs, 0,
-                       PAGE_CACHE_SIZE, NULL, do_journal_get_write_access);
+       ret = walk_page_buffers(handle, page_bufs, 0, len, NULL,
+                               do_journal_get_write_access);
 
-       err = walk_page_buffers(handle, page_bufs, 0,
-                               PAGE_CACHE_SIZE, NULL, write_end_fn);
+       err = walk_page_buffers(handle, page_bufs, 0, len, NULL,
+                               write_end_fn);
        if (ret == 0)
                ret = err;
        err = ext4_journal_stop(handle);
        if (!ret)
                ret = err;
 
-       walk_page_buffers(handle, page_bufs, 0,
-                               PAGE_CACHE_SIZE, NULL, bput_one);
+       walk_page_buffers(handle, page_bufs, 0, len, NULL, bput_one);
        EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
        goto out;