[rfc][patch 3/3] fs: convert ext2,tmpfs to new truncate

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Convert filemap_xip.c, buffer.c, and some filesystems to the new truncate
convention. Converting generic helpers is using some ugly code (testing
for i_op->ftruncate) to distinguish new and old callers... better
alternative might be just define a new function for these guys.
---
 fs/buffer.c      |   40 +++++++++++++++++--------
 fs/ext2/ext2.h   |    2 -
 fs/ext2/file.c   |    2 -
 fs/ext2/inode.c  |   85 ++++++++++++++++++++++++++++++++++++++++++-------------
 mm/filemap_xip.c |   15 +++++++--
 mm/shmem.c       |   40 ++++++++++++++++---------
 6 files changed, 133 insertions(+), 51 deletions(-)

Index: linux-2.6/fs/ext2/inode.c
===================================================================
--- linux-2.6.orig/fs/ext2/inode.c
+++ linux-2.6/fs/ext2/inode.c
@@ -68,7 +68,7 @@ void ext2_delete_inode (struct inode * i
 
 	inode->i_size = 0;
 	if (inode->i_blocks)
-		ext2_truncate (inode);
+		ext2_ftruncate(NULL, 0, inode, 0);
 	ext2_free_inode (inode);
 
 	return;
@@ -761,8 +761,31 @@ ext2_write_begin(struct file *file, stru
 		loff_t pos, unsigned len, unsigned flags,
 		struct page **pagep, void **fsdata)
 {
+	int ret;
+
 	*pagep = NULL;
-	return __ext2_write_begin(file, mapping, pos, len, flags, pagep,fsdata);
+	ret = __ext2_write_begin(file, mapping, pos, len, flags, pagep,fsdata);
+	if (ret < 0) {
+		loff_t isize = inode->i_size;
+		if (pos + len > isize)
+			ext2_ftruncate(NULL, 0, inode, isize);
+	}
+	return ret;
+}
+
+static int ext2_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	int ret;
+
+	ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
+	if (ret < len) {
+		loff_t isize = inode->i_size;
+		if (pos + len > isize)
+			ext2_ftruncate(NULL, 0, inode, isize);
+	}
+	return ret;
 }
 
 static int
@@ -770,13 +793,22 @@ ext2_nobh_write_begin(struct file *file,
 		loff_t pos, unsigned len, unsigned flags,
 		struct page **pagep, void **fsdata)
 {
+	int ret;
+
 	/*
 	 * Dir-in-pagecache still uses ext2_write_begin. Would have to rework
 	 * directory handling code to pass around offsets rather than struct
 	 * pages in order to make this work easily.
 	 */
-	return nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
+	ret = nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
 							ext2_get_block);
+	if (ret < 0) {
+		loff_t isize;
+		isize = i_size_read(inode);
+		if (pos + len > isize)
+			ext2_ftruncate(NULL, 0, inode, isize);
+	}
+	return ret;
 }
 
 static int ext2_nobh_writepage(struct page *page,
@@ -796,9 +828,15 @@ ext2_direct_IO(int rw, struct kiocb *ioc
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
+	ssize_t ret;
 
-	return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
+	ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
 				offset, nr_segs, ext2_get_block, NULL);
+	if (ret < 0 && (rw & WRITE)) {
+		loff_t isize = i_size_read(inode);
+		ext2_ftruncate(NULL, 0, inode, isize);
+	}
+	return ret;
 }
 
 static int
@@ -813,7 +851,7 @@ const struct address_space_operations ex
 	.writepage		= ext2_writepage,
 	.sync_page		= block_sync_page,
 	.write_begin		= ext2_write_begin,
-	.write_end		= generic_write_end,
+	.write_end		= ext2_write_end,
 	.bmap			= ext2_bmap,
 	.direct_IO		= ext2_direct_IO,
 	.writepages		= ext2_writepages,
@@ -1020,7 +1058,8 @@ static void ext2_free_branches(struct in
 		ext2_free_data(inode, p, q);
 }
 
-void ext2_truncate(struct inode *inode)
+int ext2_ftruncate(struct file *file, int open,
+			struct inode *inode, loff_t offset)
 {
 	__le32 *i_data = EXT2_I(inode)->i_data;
 	struct ext2_inode_info *ei = EXT2_I(inode);
@@ -1032,31 +1071,37 @@ void ext2_truncate(struct inode *inode)
 	int n;
 	long iblock;
 	unsigned blocksize;
+	int error;
+
+	error = inode_truncate_ok(inode, offset);
+	if (error)
+		return error;
 
 	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
 	    S_ISLNK(inode->i_mode)))
-		return;
+		return -EINVAL;
 	if (ext2_inode_is_fast_symlink(inode))
-		return;
+		return -EINVAL;
 	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
-		return;
-
-	blocksize = inode->i_sb->s_blocksize;
-	iblock = (inode->i_size + blocksize-1)
-					>> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
+		return -EPERM;
 
 	if (mapping_is_xip(inode->i_mapping))
-		xip_truncate_page(inode->i_mapping, inode->i_size);
+		error = xip_truncate_page(inode->i_mapping, offset);
 	else if (test_opt(inode->i_sb, NOBH))
-		nobh_truncate_page(inode->i_mapping,
-				inode->i_size, ext2_get_block);
+		error = nobh_truncate_page(inode->i_mapping,
+				offset, ext2_get_block);
 	else
-		block_truncate_page(inode->i_mapping,
-				inode->i_size, ext2_get_block);
+		error = block_truncate_page(inode->i_mapping,
+				offset, ext2_get_block);
+	if (error)
+		return error;
+
+	blocksize = inode->i_sb->s_blocksize;
+	iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
 
 	n = ext2_block_to_path(inode, iblock, offsets, NULL);
 	if (n == 0)
-		return;
+		return 0;
 
 	/*
 	 * From here we block out all ext2_get_block() callers who want to
@@ -1127,6 +1172,8 @@ do_indirects:
 	} else {
 		mark_inode_dirty(inode);
 	}
+
+	return 0;
 }
 
 static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
Index: linux-2.6/mm/shmem.c
===================================================================
--- linux-2.6.orig/mm/shmem.c
+++ linux-2.6/mm/shmem.c
@@ -730,10 +730,11 @@ done2:
 	if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
 		/*
 		 * Call truncate_inode_pages again: racing shmem_unuse_inode
-		 * may have swizzled a page in from swap since vmtruncate or
-		 * generic_delete_inode did it, before we lowered next_index.
-		 * Also, though shmem_getpage checks i_size before adding to
-		 * cache, no recheck after: so fix the narrow window there too.
+		 * may have swizzled a page in from swap since
+		 * truncate_pagecache or generic_delete_inode did it, before we
+		 * lowered next_index.  Also, though shmem_getpage checks
+		 * i_size before adding to cache, no recheck after: so fix the
+		 * narrow window there too.
 		 *
 		 * Recalling truncate_inode_pages_range and unmap_mapping_range
 		 * every time for punch_hole (which never got a chance to clear
@@ -763,9 +764,21 @@ done2:
 	}
 }
 
-static void shmem_truncate(struct inode *inode)
+static int shmem_ftruncate(struct file *file, int open,
+			struct inode *inode, loff_t offset)
 {
-	shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
+	loff_t oldsize;
+	int error;
+
+	error = inode_truncate_ok(inode, offset);
+	if (error)
+		return error;
+	oldsize = inode->i_size;
+	i_size_write(inode, offset);
+	truncate_pagecache(inode, oldsize, offset);
+	shmem_truncate_range(inode, offset, (loff_t)-1);
+
+	return error;
 }
 
 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
@@ -822,11 +835,10 @@ static void shmem_delete_inode(struct in
 {
 	struct shmem_inode_info *info = SHMEM_I(inode);
 
-	if (inode->i_op->truncate == shmem_truncate) {
+	if (inode->i_op->ftruncate == shmem_ftruncate) {
 		truncate_inode_pages(inode->i_mapping, 0);
 		shmem_unacct_size(info->flags, inode->i_size);
-		inode->i_size = 0;
-		shmem_truncate(inode);
+		shmem_ftruncate(NULL, 0, inode, 0);
 		if (!list_empty(&info->swaplist)) {
 			mutex_lock(&shmem_swaplist_mutex);
 			list_del_init(&info->swaplist);
@@ -1627,13 +1639,13 @@ shmem_write_end(struct file *file, struc
 {
 	struct inode *inode = mapping->host;
 
-	if (pos + copied > inode->i_size)
-		i_size_write(inode, pos + copied);
-
 	unlock_page(page);
 	set_page_dirty(page);
 	page_cache_release(page);
 
+	if (pos + copied > inode->i_size)
+		i_size_write(inode, pos + copied);
+
 	return copied;
 }
 
@@ -2018,7 +2030,7 @@ static const struct inode_operations shm
 };
 
 static const struct inode_operations shmem_symlink_inode_operations = {
-	.truncate	= shmem_truncate,
+	.ftruncate	= shmem_ftruncate,
 	.readlink	= generic_readlink,
 	.follow_link	= shmem_follow_link,
 	.put_link	= shmem_put_link,
@@ -2438,7 +2450,7 @@ static const struct file_operations shme
 };
 
 static const struct inode_operations shmem_inode_operations = {
-	.truncate	= shmem_truncate,
+	.ftruncate	= shmem_ftruncate,
 	.setattr	= shmem_notify_change,
 	.truncate_range	= shmem_truncate_range,
 #ifdef CONFIG_TMPFS_POSIX_ACL
Index: linux-2.6/fs/buffer.c
===================================================================
--- linux-2.6.orig/fs/buffer.c
+++ linux-2.6/fs/buffer.c
@@ -2702,22 +2702,23 @@ int nobh_truncate_page(struct address_sp
 	struct inode *inode = mapping->host;
 	struct page *page;
 	struct buffer_head map_bh;
-	int err;
+	int err = 0;
 
 	blocksize = 1 << inode->i_blkbits;
 	length = offset & (blocksize - 1);
 
 	/* Block boundary? Nothing to do */
 	if (!length)
-		return 0;
+		goto out;
 
 	length = blocksize - length;
 	iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
 
 	page = grab_cache_page(mapping, index);
-	err = -ENOMEM;
-	if (!page)
+	if (!page) {
+		err = -ENOMEM;
 		goto out;
+	}
 
 	if (page_has_buffers(page)) {
 has_buffers:
@@ -2759,12 +2760,18 @@ has_buffers:
 	}
 	zero_user(page, offset, length);
 	set_page_dirty(page);
-	err = 0;
 
 unlock:
 	unlock_page(page);
 	page_cache_release(page);
 out:
+	if (!err && inode->i_op->ftruncate) {
+		loff_t oldsize = inode->i_size;
+
+		i_size_write(inode, from);
+		truncate_pagecache(inode, oldsize, from);
+	}
+
 	return err;
 }
 EXPORT_SYMBOL(nobh_truncate_page);
@@ -2780,22 +2787,23 @@ int block_truncate_page(struct address_s
 	struct inode *inode = mapping->host;
 	struct page *page;
 	struct buffer_head *bh;
-	int err;
+	int err = 0;
 
 	blocksize = 1 << inode->i_blkbits;
 	length = offset & (blocksize - 1);
 
 	/* Block boundary? Nothing to do */
 	if (!length)
-		return 0;
+		goto out;
 
 	length = blocksize - length;
 	iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
 	
 	page = grab_cache_page(mapping, index);
-	err = -ENOMEM;
-	if (!page)
+	if (!page) {
+		err = -ENOMEM;
 		goto out;
+	}
 
 	if (!page_has_buffers(page))
 		create_empty_buffers(page, blocksize, 0);
@@ -2809,7 +2817,6 @@ int block_truncate_page(struct address_s
 		pos += blocksize;
 	}
 
-	err = 0;
 	if (!buffer_mapped(bh)) {
 		WARN_ON(bh->b_size != blocksize);
 		err = get_block(inode, iblock, bh, 0);
@@ -2825,22 +2832,29 @@ int block_truncate_page(struct address_s
 		set_buffer_uptodate(bh);
 
 	if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
-		err = -EIO;
 		ll_rw_block(READ, 1, &bh);
 		wait_on_buffer(bh);
 		/* Uhhuh. Read error. Complain and punt. */
-		if (!buffer_uptodate(bh))
+		if (!buffer_uptodate(bh)) {
+			err = -EIO;
 			goto unlock;
+		}
 	}
 
 	zero_user(page, offset, length);
 	mark_buffer_dirty(bh);
-	err = 0;
 
 unlock:
 	unlock_page(page);
 	page_cache_release(page);
 out:
+	if (!err && inode->i_op->ftruncate) {
+		loff_t oldsize = inode->i_size;
+
+		i_size_write(inode, from);
+		truncate_pagecache(inode, oldsize, from);
+	}
+
 	return err;
 }
 
Index: linux-2.6/fs/ext2/ext2.h
===================================================================
--- linux-2.6.orig/fs/ext2/ext2.h
+++ linux-2.6/fs/ext2/ext2.h
@@ -122,7 +122,7 @@ extern int ext2_write_inode (struct inod
 extern void ext2_delete_inode (struct inode *);
 extern int ext2_sync_inode (struct inode *);
 extern int ext2_get_block(struct inode *, sector_t, struct buffer_head *, int);
-extern void ext2_truncate (struct inode *);
+extern int ext2_ftruncate(struct file *, int, struct inode *, loff_t);
 extern int ext2_setattr (struct dentry *, struct iattr *);
 extern void ext2_set_inode_flags(struct inode *inode);
 extern void ext2_get_inode_flags(struct ext2_inode_info *);
Index: linux-2.6/mm/filemap_xip.c
===================================================================
--- linux-2.6.orig/mm/filemap_xip.c
+++ linux-2.6/mm/filemap_xip.c
@@ -440,7 +440,9 @@ EXPORT_SYMBOL_GPL(xip_file_write);
 int
 xip_truncate_page(struct address_space *mapping, loff_t from)
 {
+	struct inode *inode = mapping->host;
 	pgoff_t index = from >> PAGE_CACHE_SHIFT;
+	loff_t oldsize;
 	unsigned offset = from & (PAGE_CACHE_SIZE-1);
 	unsigned blocksize;
 	unsigned length;
@@ -450,12 +452,12 @@ xip_truncate_page(struct address_space *
 
 	BUG_ON(!mapping->a_ops->get_xip_mem);
 
-	blocksize = 1 << mapping->host->i_blkbits;
+	blocksize = 1 << inode->i_blkbits;
 	length = offset & (blocksize - 1);
 
 	/* Block boundary? Nothing to do */
 	if (!length)
-		return 0;
+		goto out;
 
 	length = blocksize - length;
 
@@ -464,11 +466,18 @@ xip_truncate_page(struct address_space *
 	if (unlikely(err)) {
 		if (err == -ENODATA)
 			/* Hole? No need to truncate */
-			return 0;
+			goto out;
 		else
 			return err;
 	}
 	memset(xip_mem + offset, 0, length);
+out:
+	if (inode->i_op->ftruncate) {
+		oldsize = inode->i_size;
+		i_size_write(inode, from);
+		truncate_pagecache(inode, oldsize, from);
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(xip_truncate_page);
Index: linux-2.6/fs/ext2/file.c
===================================================================
--- linux-2.6.orig/fs/ext2/file.c
+++ linux-2.6/fs/ext2/file.c
@@ -77,7 +77,7 @@ const struct file_operations ext2_xip_fi
 #endif
 
 const struct inode_operations ext2_file_inode_operations = {
-	.truncate	= ext2_truncate,
+	.ftruncate	= ext2_ftruncate,
 #ifdef CONFIG_EXT2_FS_XATTR
 	.setxattr	= generic_setxattr,
 	.getxattr	= generic_getxattr,
--
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