ext4: convert to new aops

Convert ext4 to use write_begin()/write_end() methods.

Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Dmitriy Monakhov <dmonakhov@sw.ru>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 120 insertions, 54 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index a4848e04a5e..0df2b1e06d0 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1146,34 +1146,50 @@ static int do_journal_get_write_access(handle_t *handle,
         return ext4_journal_get_write_access(handle, bh);
 }
 
-static int ext4_prepare_write(struct file *file, struct page *page,
-                              unsigned from, unsigned to)
+static int ext4_write_begin(struct file *file, struct address_space *mapping,
+                                loff_t pos, unsigned len, unsigned flags,
+                                struct page **pagep, void **fsdata)
 {
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = mapping->host;
         int ret, needed_blocks = ext4_writepage_trans_blocks(inode);
         handle_t *handle;
         int retries = 0;
+        struct page *page;
+        pgoff_t index;
+        unsigned from, to;
+
+        index = pos >> PAGE_CACHE_SHIFT;
+        from = pos & (PAGE_CACHE_SIZE - 1);
+        to = from + len;
 
 retry:
-        handle = ext4_journal_start(inode, needed_blocks);
-        if (IS_ERR(handle)) {
-                ret = PTR_ERR(handle);
-                goto out;
+        page = __grab_cache_page(mapping, index);
+        if (!page)
+                return -ENOMEM;
+        *pagep = page;
+
+        handle = ext4_journal_start(inode, needed_blocks);
+        if (IS_ERR(handle)) {
+                unlock_page(page);
+                page_cache_release(page);
+                ret = PTR_ERR(handle);
+                goto out;
         }
-        if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
-                ret = nobh_prepare_write(page, from, to, ext4_get_block);
-        else
-                ret = block_prepare_write(page, from, to, ext4_get_block);
-        if (ret)
-                goto prepare_write_failed;
 
-        if (ext4_should_journal_data(inode)) {
+        ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
+                                                        ext4_get_block);
+
+        if (!ret && ext4_should_journal_data(inode)) {
                 ret = walk_page_buffers(handle, page_buffers(page),
                                 from, to, NULL, do_journal_get_write_access);
         }
-prepare_write_failed:
-        if (ret)
+
+        if (ret) {
                 ext4_journal_stop(handle);
+                unlock_page(page);
+                page_cache_release(page);
+        }
+
         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
                 goto retry;
 out:
@@ -1185,12 +1201,12 @@ int ext4_journal_dirty_data(handle_t *handle, struct buffer_head *bh)
         int err = jbd2_journal_dirty_data(handle, bh);
         if (err)
                 ext4_journal_abort_handle(__FUNCTION__, __FUNCTION__,
-                                                bh, handle,err);
+                                                bh, handle, err);
         return err;
 }
 
-/* For commit_write() in data=journal mode */
-static int commit_write_fn(handle_t *handle, struct buffer_head *bh)
+/* For write_end() in data=journal mode */
+static int write_end_fn(handle_t *handle, struct buffer_head *bh)
 {
         if (!buffer_mapped(bh) || buffer_freed(bh))
                 return 0;
@@ -1199,84 +1215,130 @@ static int commit_write_fn(handle_t *handle, struct buffer_head *bh)
 }
 
 /*
+ * Generic write_end handler for ordered and writeback ext4 journal modes.
+ * We can't use generic_write_end, because that unlocks the page and we need to
+ * unlock the page after ext4_journal_stop, but ext4_journal_stop must run
+ * after block_write_end.
+ */
+static int ext4_generic_write_end(struct file *file,
+                                struct address_space *mapping,
+                                loff_t pos, unsigned len, unsigned copied,
+                                struct page *page, void *fsdata)
+{
+        struct inode *inode = file->f_mapping->host;
+
+        copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
+
+        if (pos+copied > inode->i_size) {
+                i_size_write(inode, pos+copied);
+                mark_inode_dirty(inode);
+        }
+
+        return copied;
+}
+
+/*
  * We need to pick up the new inode size which generic_commit_write gave us
  * `file' can be NULL - eg, when called from page_symlink().
  *
  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
  * buffers are managed internally.
  */
-static int ext4_ordered_commit_write(struct file *file, struct page *page,
-                             unsigned from, unsigned to)
+static int ext4_ordered_write_end(struct file *file,
+                                struct address_space *mapping,
+                                loff_t pos, unsigned len, unsigned copied,
+                                struct page *page, void *fsdata)
 {
         handle_t *handle = ext4_journal_current_handle();
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = file->f_mapping->host;
+        unsigned from, to;
         int ret = 0, ret2;
 
+        from = pos & (PAGE_CACHE_SIZE - 1);
+        to = from + len;
+
         ret = walk_page_buffers(handle, page_buffers(page),
                 from, to, NULL, ext4_journal_dirty_data);
 
         if (ret == 0) {
                 /*
-                 * generic_commit_write() will run mark_inode_dirty() if i_size
+                 * generic_write_end() will run mark_inode_dirty() if i_size
                  * changes.  So let's piggyback the i_disksize mark_inode_dirty
                  * into that.
                  */
                 loff_t new_i_size;
 
-                new_i_size = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
+                new_i_size = pos + copied;
                 if (new_i_size > EXT4_I(inode)->i_disksize)
                         EXT4_I(inode)->i_disksize = new_i_size;
-                ret = generic_commit_write(file, page, from, to);
+                copied = ext4_generic_write_end(file, mapping, pos, len, copied,
+                                                        page, fsdata);
+                if (copied < 0)
+                        ret = copied;
         }
         ret2 = ext4_journal_stop(handle);
         if (!ret)
                 ret = ret2;
-        return ret;
+        unlock_page(page);
+        page_cache_release(page);
+
+        return ret ? ret : copied;
 }
 
-static int ext4_writeback_commit_write(struct file *file, struct page *page,
-                             unsigned from, unsigned to)
+static int ext4_writeback_write_end(struct file *file,
+                                struct address_space *mapping,
+                                loff_t pos, unsigned len, unsigned copied,
+                                struct page *page, void *fsdata)
 {
         handle_t *handle = ext4_journal_current_handle();
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = file->f_mapping->host;
         int ret = 0, ret2;
         loff_t new_i_size;
 
-        new_i_size = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
+        new_i_size = pos + copied;
         if (new_i_size > EXT4_I(inode)->i_disksize)
                 EXT4_I(inode)->i_disksize = new_i_size;
 
-        if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
-                ret = nobh_commit_write(file, page, from, to);
-        else
-                ret = generic_commit_write(file, page, from, to);
+        copied = ext4_generic_write_end(file, mapping, pos, len, copied,
+                                                        page, fsdata);
+        if (copied < 0)
+                ret = copied;
 
         ret2 = ext4_journal_stop(handle);
         if (!ret)
                 ret = ret2;
-        return ret;
+        unlock_page(page);
+        page_cache_release(page);
+
+        return ret ? ret : copied;
 }
 
-static int ext4_journalled_commit_write(struct file *file,
-                        struct page *page, unsigned from, unsigned to)
+static int ext4_journalled_write_end(struct file *file,
+                                struct address_space *mapping,
+                                loff_t pos, unsigned len, unsigned copied,
+                                struct page *page, void *fsdata)
 {
         handle_t *handle = ext4_journal_current_handle();
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = mapping->host;
         int ret = 0, ret2;
         int partial = 0;
-        loff_t pos;
+        unsigned from, to;
 
-        /*
-         * Here we duplicate the generic_commit_write() functionality
-         */
-        pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
+        from = pos & (PAGE_CACHE_SIZE - 1);
+        to = from + len;
+
+        if (copied < len) {
+                if (!PageUptodate(page))
+                        copied = 0;
+                page_zero_new_buffers(page, from+copied, to);
+        }
 
         ret = walk_page_buffers(handle, page_buffers(page), from,
-                                to, &partial, commit_write_fn);
+                                to, &partial, write_end_fn);
         if (!partial)
                 SetPageUptodate(page);
-        if (pos > inode->i_size)
-                i_size_write(inode, pos);
+        if (pos+copied > inode->i_size)
+                i_size_write(inode, pos+copied);
         EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
         if (inode->i_size > EXT4_I(inode)->i_disksize) {
                 EXT4_I(inode)->i_disksize = inode->i_size;
@@ -1284,10 +1346,14 @@ static int ext4_journalled_commit_write(struct file *file,
                 if (!ret)
                         ret = ret2;
         }
+
         ret2 = ext4_journal_stop(handle);
         if (!ret)
                 ret = ret2;
-        return ret;
+        unlock_page(page);
+        page_cache_release(page);
+
+        return ret ? ret : copied;
 }
 
 /*
@@ -1545,7 +1611,7 @@ static int ext4_journalled_writepage(struct page *page,
                         PAGE_CACHE_SIZE, NULL, do_journal_get_write_access);
 
                 err = walk_page_buffers(handle, page_buffers(page), 0,
-                                PAGE_CACHE_SIZE, NULL, commit_write_fn);
+                                PAGE_CACHE_SIZE, NULL, write_end_fn);
                 if (ret == 0)
                         ret = err;
                 EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
@@ -1705,8 +1771,8 @@ static const struct address_space_operations ext4_ordered_aops = {
         .readpages      = ext4_readpages,
         .writepage      = ext4_ordered_writepage,
         .sync_page      = block_sync_page,
-        .prepare_write  = ext4_prepare_write,
-        .commit_write   = ext4_ordered_commit_write,
+        .write_begin    = ext4_write_begin,
+        .write_end      = ext4_ordered_write_end,
         .bmap           = ext4_bmap,
         .invalidatepage = ext4_invalidatepage,
         .releasepage    = ext4_releasepage,
@@ -1719,8 +1785,8 @@ static const struct address_space_operations ext4_writeback_aops = {
         .readpages      = ext4_readpages,
         .writepage      = ext4_writeback_writepage,
         .sync_page      = block_sync_page,
-        .prepare_write  = ext4_prepare_write,
-        .commit_write   = ext4_writeback_commit_write,
+        .write_begin    = ext4_write_begin,
+        .write_end      = ext4_writeback_write_end,
         .bmap           = ext4_bmap,
         .invalidatepage = ext4_invalidatepage,
         .releasepage    = ext4_releasepage,
@@ -1733,8 +1799,8 @@ static const struct address_space_operations ext4_journalled_aops = {
         .readpages      = ext4_readpages,
         .writepage      = ext4_journalled_writepage,
         .sync_page      = block_sync_page,
-        .prepare_write  = ext4_prepare_write,
-        .commit_write   = ext4_journalled_commit_write,
+        .write_begin    = ext4_write_begin,
+        .write_end      = ext4_journalled_write_end,
         .set_page_dirty = ext4_journalled_set_page_dirty,
         .bmap           = ext4_bmap,
         .invalidatepage = ext4_invalidatepage,