ocfs2: rework ocfs2_buffered_write_cluster()

Use some ideas from the new-aops patch series and turn
ocfs2_buffered_write_cluster() into a 2 stage operation with the caller
copying data in between. The code now understands multiple cluster writes as
a result of having to deal with a full page write for greater than 4k pages.

This sets us up to easily call into the write path during ->page_mkwrite().

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

1 files changed, 67 insertions, 54 deletions

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 566f9b70ec91..4c850d00c269 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1335,15 +1335,16 @@ ocfs2_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
         *basep = base;
 }
 
-static struct page * ocfs2_get_write_source(struct ocfs2_buffered_write_priv *bp,
+static struct page * ocfs2_get_write_source(char **ret_src_buf,
                                             const struct iovec *cur_iov,
                                             size_t iov_offset)
 {
         int ret;
-        char *buf;
+        char *buf = cur_iov->iov_base + iov_offset;
         struct page *src_page = NULL;
+        unsigned long off;
 
-        buf = cur_iov->iov_base + iov_offset;
+        off = (unsigned long)(buf) & ~PAGE_CACHE_MASK;
 
         if (!segment_eq(get_fs(), KERNEL_DS)) {
                 /*
@@ -1355,18 +1356,17 @@ static struct page * ocfs2_get_write_source(struct ocfs2_buffered_write_priv *bp
                                      (unsigned long)buf & PAGE_CACHE_MASK, 1,
                                      0, 0, &src_page, NULL);
                 if (ret == 1)
-                        bp->b_src_buf = kmap(src_page);
+                        *ret_src_buf = kmap(src_page) + off;
                 else
                         src_page = ERR_PTR(-EFAULT);
         } else {
-                bp->b_src_buf = buf;
+                *ret_src_buf = buf;
         }
 
         return src_page;
 }
 
-static void ocfs2_put_write_source(struct ocfs2_buffered_write_priv *bp,
-                                   struct page *page)
+static void ocfs2_put_write_source(struct page *page)
 {
         if (page) {
                 kunmap(page);
@@ -1382,10 +1382,12 @@ static ssize_t ocfs2_file_buffered_write(struct file *file, loff_t *ppos,
 {
         int ret = 0;
         ssize_t copied, total = 0;
-        size_t iov_offset = 0;
+        size_t iov_offset = 0, bytes;
+        loff_t pos;
         const struct iovec *cur_iov = iov;
-        struct ocfs2_buffered_write_priv bp;
-        struct page *page;
+        struct page *user_page, *page;
+        char *buf, *dst;
+        void *fsdata;
 
         /*
          * handle partial DIO write.  Adjust cur_iov if needed.
@@ -1393,21 +1395,38 @@ static ssize_t ocfs2_file_buffered_write(struct file *file, loff_t *ppos,
         ocfs2_set_next_iovec(&cur_iov, &iov_offset, o_direct_written);
 
         do {
-                bp.b_cur_off = iov_offset;
-                bp.b_cur_iov = cur_iov;
+                pos = *ppos;
 
-                page = ocfs2_get_write_source(&bp, cur_iov, iov_offset);
-                if (IS_ERR(page)) {
-                        ret = PTR_ERR(page);
+                user_page = ocfs2_get_write_source(&buf, cur_iov, iov_offset);
+                if (IS_ERR(user_page)) {
+                        ret = PTR_ERR(user_page);
                         goto out;
                 }
 
-                copied = ocfs2_buffered_write_cluster(file, *ppos, count,
-                                                      ocfs2_map_and_write_user_data,
-                                                      &bp);
+                /* Stay within our page boundaries */
+                bytes = min((PAGE_CACHE_SIZE - ((unsigned long)pos & ~PAGE_CACHE_MASK)),
+                            (PAGE_CACHE_SIZE - ((unsigned long)buf & ~PAGE_CACHE_MASK)));
+                /* Stay within the vector boundary */
+                bytes = min_t(size_t, bytes, cur_iov->iov_len - iov_offset);
+                /* Stay within count */
+                bytes = min(bytes, count);
+
+                page = NULL;
+                ret = ocfs2_write_begin(file, file->f_mapping, pos, bytes, 0,
+                                        &page, &fsdata);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
 
-                ocfs2_put_write_source(&bp, page);
+                dst = kmap_atomic(page, KM_USER0);
+                memcpy(dst + (pos & (PAGE_CACHE_SIZE - 1)), buf, bytes);
+                kunmap_atomic(dst, KM_USER0);
+                flush_dcache_page(page);
+                ocfs2_put_write_source(user_page);
 
+                copied = ocfs2_write_end(file, file->f_mapping, pos, bytes,
+                                         bytes, page, fsdata);
                 if (copied < 0) {
                         mlog_errno(copied);
                         ret = copied;
@@ -1415,7 +1434,7 @@ static ssize_t ocfs2_file_buffered_write(struct file *file, loff_t *ppos,
                 }
 
                 total += copied;
-                *ppos = *ppos + copied;
+                *ppos = pos + copied;
                 count -= copied;
 
                 ocfs2_set_next_iovec(&cur_iov, &iov_offset, copied);
@@ -1585,52 +1604,46 @@ static int ocfs2_splice_write_actor(struct pipe_inode_info *pipe,
                                     struct pipe_buffer *buf,
                                     struct splice_desc *sd)
 {
-        int ret, count, total = 0;
+        int ret, count;
         ssize_t copied = 0;
-        struct ocfs2_splice_write_priv sp;
+        struct file *file = sd->u.file;
+        unsigned int offset;
+        struct page *page = NULL;
+        void *fsdata;
+        char *src, *dst;
 
         ret = buf->ops->confirm(pipe, buf);
         if (ret)
                 goto out;
 
-        sp.s_sd = sd;
-        sp.s_buf = buf;
-        sp.s_pipe = pipe;
-        sp.s_offset = sd->pos & ~PAGE_CACHE_MASK;
-        sp.s_buf_offset = buf->offset;
-
+        offset = sd->pos & ~PAGE_CACHE_MASK;
         count = sd->len;
-        if (count + sp.s_offset > PAGE_CACHE_SIZE)
-                count = PAGE_CACHE_SIZE - sp.s_offset;
+        if (count + offset > PAGE_CACHE_SIZE)
+                count = PAGE_CACHE_SIZE - offset;
 
-        do {
-                /*
-                 * splice wants us to copy up to one page at a
-                 * time. For pagesize > cluster size, this means we
-                 * might enter ocfs2_buffered_write_cluster() more
-                 * than once, so keep track of our progress here.
-                 */
-                copied = ocfs2_buffered_write_cluster(sd->u.file,
-                                                      (loff_t)sd->pos + total,
-                                                      count,
-                                                      ocfs2_map_and_write_splice_data,
-                                                      &sp);
-                if (copied < 0) {
-                        mlog_errno(copied);
-                        ret = copied;
-                        goto out;
-                }
+        ret = ocfs2_write_begin(file, file->f_mapping, sd->pos, count, 0,
+                                &page, &fsdata);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
 
-                count -= copied;
-                sp.s_offset += copied;
-                sp.s_buf_offset += copied;
-                total += copied;
-        } while (count);
+        src = buf->ops->map(pipe, buf, 1);
+        dst = kmap_atomic(page, KM_USER1);
+        memcpy(dst + offset, src + buf->offset, count);
+        kunmap_atomic(page, KM_USER1);
+        buf->ops->unmap(pipe, buf, src);
 
-        ret = 0;
+        copied = ocfs2_write_end(file, file->f_mapping, sd->pos, count, count,
+                                 page, fsdata);
+        if (copied < 0) {
+                mlog_errno(copied);
+                ret = copied;
+                goto out;
+        }
 out:
 
-        return total ? total : ret;
+        return copied ? copied : ret;
 }
 
 static ssize_t __ocfs2_file_splice_write(struct pipe_inode_info *pipe,