consolidate generic_writepages and mpage_writepages
Clean up massive code duplication between mpage_writepages() and
generic_writepages().
The new generic function, write_cache_pages() takes a function pointer
argument, which will be called for each page to be written.
Maybe cifs_writepages() too can use this infrastructure, but I'm not
touching that with a ten-foot pole.
The upcoming page writeback support in fuse will also want this.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 63cd888..eec1481 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -588,31 +588,27 @@
}
/**
- * generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them.
+ * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
* @mapping: address space structure to write
* @wbc: subtract the number of written pages from *@wbc->nr_to_write
+ * @writepage: function called for each page
+ * @data: data passed to writepage function
*
- * This is a library function, which implements the writepages()
- * address_space_operation.
- *
- * If a page is already under I/O, generic_writepages() skips it, even
+ * If a page is already under I/O, write_cache_pages() skips it, even
* if it's dirty. This is desirable behaviour for memory-cleaning writeback,
* but it is INCORRECT for data-integrity system calls such as fsync(). fsync()
* and msync() need to guarantee that all the data which was dirty at the time
* the call was made get new I/O started against them. If wbc->sync_mode is
* WB_SYNC_ALL then we were called for data integrity and we must wait for
* existing IO to complete.
- *
- * Derived from mpage_writepages() - if you fix this you should check that
- * also!
*/
-int generic_writepages(struct address_space *mapping,
- struct writeback_control *wbc)
+int write_cache_pages(struct address_space *mapping,
+ struct writeback_control *wbc, writepage_t writepage,
+ void *data)
{
struct backing_dev_info *bdi = mapping->backing_dev_info;
int ret = 0;
int done = 0;
- int (*writepage)(struct page *page, struct writeback_control *wbc);
struct pagevec pvec;
int nr_pages;
pgoff_t index;
@@ -625,12 +621,6 @@
return 0;
}
- writepage = mapping->a_ops->writepage;
-
- /* deal with chardevs and other special file */
- if (!writepage)
- return 0;
-
pagevec_init(&pvec, 0);
if (wbc->range_cyclic) {
index = mapping->writeback_index; /* Start from prev offset */
@@ -682,8 +672,7 @@
continue;
}
- ret = (*writepage)(page, wbc);
- mapping_set_error(mapping, ret);
+ ret = (*writepage)(page, wbc, data);
if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
unlock_page(page);
@@ -710,6 +699,38 @@
mapping->writeback_index = index;
return ret;
}
+EXPORT_SYMBOL(write_cache_pages);
+
+/*
+ * Function used by generic_writepages to call the real writepage
+ * function and set the mapping flags on error
+ */
+static int __writepage(struct page *page, struct writeback_control *wbc,
+ void *data)
+{
+ struct address_space *mapping = data;
+ int ret = mapping->a_ops->writepage(page, wbc);
+ mapping_set_error(mapping, ret);
+ return ret;
+}
+
+/**
+ * generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them.
+ * @mapping: address space structure to write
+ * @wbc: subtract the number of written pages from *@wbc->nr_to_write
+ *
+ * This is a library function, which implements the writepages()
+ * address_space_operation.
+ */
+int generic_writepages(struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+ /* deal with chardevs and other special file */
+ if (!mapping->a_ops->writepage)
+ return 0;
+
+ return write_cache_pages(mapping, wbc, __writepage, mapping);
+}
EXPORT_SYMBOL(generic_writepages);