Add block_write_full_page_endio for passing endio handler

block_write_full_page doesn't allow the caller to control what happens
when the IO is over.  This adds a new call named block_write_full_page_endio
so the buffer head end_io handler can be provided by the caller.

This will be used by the ext3 data=guarded mode to do i_size updates in
a workqueue based end_io handler.  end_buffer_async_write is also
exported so it can be called to do the dirty work of managing page
writeback for the higher level end_io handler.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
Acked-by: Theodore Tso <tytso@mit.edu>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/buffer.c b/fs/buffer.c
index ff8bb1f..b3e5be7 100644 (file)
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -360,7 +360,7 @@ still_busy:
  * Completion handler for block_write_full_page() - pages which are unlocked
  * during I/O, and which have PageWriteback cleared upon I/O completion.
  */
-static void end_buffer_async_write(struct buffer_head *bh, int uptodate)
+void end_buffer_async_write(struct buffer_head *bh, int uptodate)
 {
        char b[BDEVNAME_SIZE];
        unsigned long flags;
@@ -438,11 +438,17 @@ static void mark_buffer_async_read(struct buffer_head *bh)
        set_buffer_async_read(bh);
 }
 
-void mark_buffer_async_write(struct buffer_head *bh)
+void mark_buffer_async_write_endio(struct buffer_head *bh,
+                                  bh_end_io_t *handler)
 {
-       bh->b_end_io = end_buffer_async_write;
+       bh->b_end_io = handler;
        set_buffer_async_write(bh);
 }
+
+void mark_buffer_async_write(struct buffer_head *bh)
+{
+       mark_buffer_async_write_endio(bh, end_buffer_async_write);
+}
 EXPORT_SYMBOL(mark_buffer_async_write);
 
 
@@ -1615,7 +1621,8 @@ EXPORT_SYMBOL(unmap_underlying_metadata);
  * unplugging the device queue.
  */
 static int __block_write_full_page(struct inode *inode, struct page *page,
-                       get_block_t *get_block, struct writeback_control *wbc)
+                       get_block_t *get_block, struct writeback_control *wbc,
+                       bh_end_io_t *handler)
 {
        int err;
        sector_t block;
@@ -1700,7 +1707,7 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
                        continue;
                }
                if (test_clear_buffer_dirty(bh)) {
-                       mark_buffer_async_write(bh);
+                       mark_buffer_async_write_endio(bh, handler);
                } else {
                        unlock_buffer(bh);
                }
@@ -1753,7 +1760,7 @@ recover:
                if (buffer_mapped(bh) && buffer_dirty(bh) &&
                    !buffer_delay(bh)) {
                        lock_buffer(bh);
-                       mark_buffer_async_write(bh);
+                       mark_buffer_async_write_endio(bh, handler);
                } else {
                        /*
                         * The buffer may have been set dirty during
@@ -2679,7 +2686,8 @@ int nobh_writepage(struct page *page, get_block_t *get_block,
 out:
        ret = mpage_writepage(page, get_block, wbc);
        if (ret == -EAGAIN)
-               ret = __block_write_full_page(inode, page, get_block, wbc);
+               ret = __block_write_full_page(inode, page, get_block, wbc,
+                                             end_buffer_async_write);
        return ret;
 }
 EXPORT_SYMBOL(nobh_writepage);
@@ -2837,9 +2845,10 @@ out:
 
 /*
  * The generic ->writepage function for buffer-backed address_spaces
+ * this form passes in the end_io handler used to finish the IO.
  */
-int block_write_full_page(struct page *page, get_block_t *get_block,
-                       struct writeback_control *wbc)
+int block_write_full_page_endio(struct page *page, get_block_t *get_block,
+                       struct writeback_control *wbc, bh_end_io_t *handler)
 {
        struct inode * const inode = page->mapping->host;
        loff_t i_size = i_size_read(inode);
@@ -2848,7 +2857,8 @@ int block_write_full_page(struct page *page, get_block_t *get_block,
 
        /* Is the page fully inside i_size? */
        if (page->index < end_index)
-               return __block_write_full_page(inode, page, get_block, wbc);
+               return __block_write_full_page(inode, page, get_block, wbc,
+                                              handler);
 
        /* Is the page fully outside i_size? (truncate in progress) */
        offset = i_size & (PAGE_CACHE_SIZE-1);
@@ -2871,9 +2881,20 @@ int block_write_full_page(struct page *page, get_block_t *get_block,
         * writes to that region are not written out to the file."
         */
        zero_user_segment(page, offset, PAGE_CACHE_SIZE);
-       return __block_write_full_page(inode, page, get_block, wbc);
+       return __block_write_full_page(inode, page, get_block, wbc, handler);
 }
 
+/*
+ * The generic ->writepage function for buffer-backed address_spaces
+ */
+int block_write_full_page(struct page *page, get_block_t *get_block,
+                       struct writeback_control *wbc)
+{
+       return block_write_full_page_endio(page, get_block, wbc,
+                                          end_buffer_async_write);
+}
+
+
 sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
                            get_block_t *get_block)
 {
@@ -3342,9 +3363,11 @@ EXPORT_SYMBOL(block_read_full_page);
 EXPORT_SYMBOL(block_sync_page);
 EXPORT_SYMBOL(block_truncate_page);
 EXPORT_SYMBOL(block_write_full_page);
+EXPORT_SYMBOL(block_write_full_page_endio);
 EXPORT_SYMBOL(cont_write_begin);
 EXPORT_SYMBOL(end_buffer_read_sync);
 EXPORT_SYMBOL(end_buffer_write_sync);
+EXPORT_SYMBOL(end_buffer_async_write);
 EXPORT_SYMBOL(file_fsync);
 EXPORT_SYMBOL(generic_block_bmap);
 EXPORT_SYMBOL(generic_cont_expand_simple);

diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 7b73bb8..16ed028 100644 (file)
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -155,6 +155,7 @@ void create_empty_buffers(struct page *, unsigned long,
                        unsigned long b_state);
 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
+void end_buffer_async_write(struct buffer_head *bh, int uptodate);
 
 /* Things to do with buffers at mapping->private_list */
 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
@@ -197,6 +198,8 @@ extern int buffer_heads_over_limit;
 void block_invalidatepage(struct page *page, unsigned long offset);
 int block_write_full_page(struct page *page, get_block_t *get_block,
                                struct writeback_control *wbc);
+int block_write_full_page_endio(struct page *page, get_block_t *get_block,
+                       struct writeback_control *wbc, bh_end_io_t *handler);
 int block_read_full_page(struct page*, get_block_t*);
 int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
                                unsigned long from);