[PATCH] generic_file_buffered_write(): handle zero-length iovec segments

[pandora-kernel.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index d504d6e..648f2c0 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2069,7 +2069,7 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
 {
        struct file *file = iocb->ki_filp;
        struct address_space * mapping = file->f_mapping;
-       struct address_space_operations *a_ops = mapping->a_ops;
+       const struct address_space_operations *a_ops = mapping->a_ops;
        struct inode    *inode = mapping->host;
        long            status = 0;
        struct page     *page;
@@ -2125,6 +2125,12 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
                        break;
                }
 
+               if (unlikely(bytes == 0)) {
+                       status = 0;
+                       copied = 0;
+                       goto zero_length_segment;
+               }
+
                status = a_ops->prepare_write(file, page, offset, offset+bytes);
                if (unlikely(status)) {
                        loff_t isize = i_size_read(inode);
@@ -2154,7 +2160,8 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
                        page_cache_release(page);
                        continue;
                }
-               if (likely(copied > 0)) {
+zero_length_segment:
+               if (likely(copied >= 0)) {
                        if (!status)
                                status = copied;
 
@@ -2219,7 +2226,7 @@ __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
                                unsigned long nr_segs, loff_t *ppos)
 {
        struct file *file = iocb->ki_filp;
-       struct address_space * mapping = file->f_mapping;
+       const struct address_space * mapping = file->f_mapping;
        size_t ocount;          /* original count */
        size_t count;           /* after file limit checks */
        struct inode    *inode = mapping->host;