[PATCH] reiserfs direct I/O support for 2.5 kernel

The patch below adds direct I/O support in Reiserfs for 2.5 kernel.

Thanks,
Mingming



diff -urN linux-2.5.64/fs/reiserfs/inode.c 2564-rf-dio/fs/reiserfs/inode.c
--- linux-2.5.64/fs/reiserfs/inode.c	Tue Mar  4 19:29:15 2003
+++ 2564-rf-dio/fs/reiserfs/inode.c	Thu Mar 13 16:59:07 2003
@@ -304,7 +304,7 @@
 	** read old data off disk.  Set the up to date bit on the buffer instead
 	** and jump to the end
 	*/
-	    if (PageUptodate(bh_result->b_page)) {
+	    if (!bh_result->b_page || PageUptodate(bh_result->b_page)) {
 		set_buffer_uptodate(bh_result);
 		goto finished ;
     }
@@ -418,6 +418,40 @@
     return reiserfs_get_block(inode, block, bh_result, GET_BLOCK_NO_HOLE) ;
 }
 
+static int reiserfs_get_block_direct_io (struct inode * inode, 
+			sector_t iblock, unsigned long max_blocks, 
+			struct buffer_head * bh_result, int create) {
+    int ret ;
+
+    bh_result->b_size = (1 << inode->i_blkbits);
+    bh_result->b_page = NULL;
+
+    ret = reiserfs_get_block(inode, iblock, bh_result, create) ;
+
+    if (ret != 0)
+	return ret;
+
+    /* don't allow direct io onto tail pages */
+    if (buffer_mapped(bh_result) && bh_result->b_blocknr == 0) {
+	/* make sure future calls to the direct io funcs for this offset
+	** in the file fail by unmapping the buffer
+	*/
+	reiserfs_unmap_buffer(bh_result);
+	ret = -EINVAL ;
+    }
+
+    /* Possible unpacked tail. Flush the data before pages have
+        disappeared */
+    if (REISERFS_I(inode)->i_flags & i_pack_on_close_mask) {
+	lock_kernel();
+	reiserfs_commit_for_inode(inode);
+	REISERFS_I(inode)->i_flags &= ~i_pack_on_close_mask;
+	unlock_kernel();
+    }
+
+    return ret ;
+}
+
 /*
 ** helper function for when reiserfs_get_block is called for a hole
 ** but the file tail is still in a direct item
@@ -446,7 +480,7 @@
     tail_end = (tail_start | (bh_result->b_size - 1)) + 1 ;
 
     index = tail_offset >> PAGE_CACHE_SHIFT ;
-    if (index != hole_page->index) {
+    if (!hole_page || index != hole_page->index) {
 	tail_page = grab_cache_page(inode->i_mapping, index) ;
 	retval = -ENOMEM;
 	if (!tail_page) {
@@ -552,7 +586,15 @@
 	return ret;
     }
 
-    REISERFS_I(inode)->i_flags |= i_pack_on_close_mask ;
+   /* If file is of such a size, that it might have a tail and tails are enabled
+    ** we should mark it as possibly needing tail packing on close
+    */
+    if ( (have_large_tails (inode->i_sb) && 
+		inode->i_size < i_block_size (inode)*4) || 
+		(have_small_tails (inode->i_sb) && 
+		inode->i_size < i_block_size(inode)) )
+
+	REISERFS_I(inode)->i_flags |= i_pack_on_close_mask ;
 
     windex = push_journal_writer("reiserfs_get_block") ;
   
@@ -742,22 +784,27 @@
 	    ** the disk
 	    */
 	    set_buffer_uptodate (unbh);
-
-	    /* we've converted the tail, so we must 
-	    ** flush unbh before the transaction commits
-	    */
-	    add_to_flushlist(inode, unbh) ;
-
-	    /* mark it dirty now to prevent commit_write from adding
-	     ** this buffer to the inode's dirty buffer list
-	     */
+	    /* unbh->b_page == NULL in case of DIRECT_IO request, this means
+               buffer will disappear shortly, so it should not be added to
+               any of our lists.
+            */
+            if ( unbh->b_page ) {
+		/* we've converted the tail, so we must
+		** flush unbh before the transaction commits
+		*/
+		add_to_flushlist(inode, unbh) ;
+
+		/* mark it dirty now to prevent commit_write from adding
+		** this buffer to the inode's dirty buffer list
+		*/
 		/*
 		 * AKPM: changed __mark_buffer_dirty to mark_buffer_dirty().
 		 * It's still atomic, but it sets the page dirty too,
 		 * which makes it eligible for writeback at any time by the
 		 * VM (which was also the case with __mark_buffer_dirty())
 		 */
-	    mark_buffer_dirty(unbh) ;
+		mark_buffer_dirty(unbh) ;
+		}
 
 	    //inode->i_blocks += inode->i_sb->s_blocksize / 512;
 	    //mark_tail_converted (inode);
@@ -2156,6 +2203,15 @@
     if (pos > inode->i_size) {
 	struct reiserfs_transaction_handle th ;
 	reiserfs_write_lock(inode->i_sb);
+	/* If the file have grown beyond the border where it
+           can have a tail, unmark it as needing a tail
+	   packing */
+        if ( (have_large_tails (inode->i_sb) && 
+		inode->i_size < i_block_size(inode)*4) || 
+		(have_small_tails (inode->i_sb) && 
+		inode->i_size < i_block_size(inode)) )
+	   REISERFS_I(inode)->i_flags  &= ~i_pack_on_close_mask ;
+
 	journal_begin(&th, inode->i_sb, 1) ;
 	reiserfs_update_inode_transaction(inode) ;
 	inode->i_size = pos ;
@@ -2214,6 +2270,17 @@
     return ret ;
 }
 
+static int reiserfs_direct_IO(int rw, struct kiocb *iocb, 
+			const struct iovec *iov, loff_t offset, 
+			unsigned long nr_segs)
+{
+    struct file *file = iocb->ki_filp;
+    struct inode *inode = file->f_dentry->d_inode->i_mapping->host;
+
+    return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
+			offset, nr_segs, reiserfs_get_block_direct_io);
+}
+
 struct address_space_operations reiserfs_address_space_operations = {
     .writepage = reiserfs_writepage,
     .readpage = reiserfs_readpage, 
@@ -2222,5 +2289,6 @@
     .sync_page = block_sync_page,
     .prepare_write = reiserfs_prepare_write,
     .commit_write = reiserfs_commit_write,
-    .bmap = reiserfs_aop_bmap
+    .bmap = reiserfs_aop_bmap,
+    .direct_IO = reiserfs_direct_IO
 } ;
diff -urN linux-2.5.64/fs/reiserfs/tail_conversion.c 2564-rf-dio/fs/reiserfs/tail_conversion.c
--- linux-2.5.64/fs/reiserfs/tail_conversion.c	Tue Mar  4 19:29:57 2003
+++ 2564-rf-dio/fs/reiserfs/tail_conversion.c	Thu Mar 13 16:59:07 2003
@@ -105,8 +105,10 @@
 	/* we only send the unbh pointer if the buffer is not up to date.
 	** this avoids overwriting good data from writepage() with old data
 	** from the disk or buffer cache
+	** Special case: unbh->b_page will be NULL if we are coming through
+	** DIRECT_IO handler here.
 	*/
-	if (buffer_uptodate(unbh) || PageUptodate(unbh->b_page)) {
+	if (!unbh->b_page || buffer_uptodate(unbh) || PageUptodate(unbh->b_page)) {
 	    up_to_date_bh = NULL ;
 	} else {
 	    up_to_date_bh = unbh ;