[16/17] ext2: Variable order page cache support

[clameter@sgi.com]

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This adds variable page size support. It is then possible to mount filesystems
that have a larger blocksize than the page size.

F.e. the following is possible on x86_64 and i386 that have only a 4k page
size.

mke2fs -b 16384 /dev/hdd2	<Ignore warning about too large block size>

mount /dev/hdd2 /media
ls -l /media

.... Do more things with the volume that uses a 16k page cache size on
a 4k page sized platform..

We disable mmap for higher order pages like also done for ramfs. This
is temporary until we get support for mmapping higher order pages.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
 fs/ext2/dir.c   |   40 +++++++++++++++++++++++-----------------
 fs/ext2/ext2.h  |    1 +
 fs/ext2/file.c  |   18 ++++++++++++++++++
 fs/ext2/inode.c |   10 ++++++++--
 fs/ext2/namei.c |   10 ++++++++--
 5 files changed, 58 insertions(+), 21 deletions(-)

Index: linux-2.6.21-rc7/fs/ext2/dir.c
===================================================================
--- linux-2.6.21-rc7.orig/fs/ext2/dir.c	2007-04-23 22:26:18.000000000 -0700
+++ linux-2.6.21-rc7/fs/ext2/dir.c	2007-04-23 22:27:52.000000000 -0700
@@ -44,7 +44,8 @@ static inline void ext2_put_page(struct 
 
 static inline unsigned long dir_pages(struct inode *inode)
 {
-	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
+	return (inode->i_size+page_cache_size(inode->i_mapping)-1)>>
+			page_cache_shift(inode->i_mapping);
 }
 
 /*
@@ -55,10 +56,11 @@ static unsigned
 ext2_last_byte(struct inode *inode, unsigned long page_nr)
 {
 	unsigned last_byte = inode->i_size;
+	struct address_space *mapping = inode->i_mapping;
 
-	last_byte -= page_nr << PAGE_CACHE_SHIFT;
-	if (last_byte > PAGE_CACHE_SIZE)
-		last_byte = PAGE_CACHE_SIZE;
+	last_byte -= page_nr << page_cache_shift(mapping);
+	if (last_byte > page_cache_size(mapping))
+		last_byte = page_cache_size(mapping);
 	return last_byte;
 }
 
@@ -77,18 +79,19 @@ static int ext2_commit_chunk(struct page
 
 static void ext2_check_page(struct page *page)
 {
-	struct inode *dir = page->mapping->host;
+	struct address_space *mapping = page->mapping;
+	struct inode *dir = mapping->host;
 	struct super_block *sb = dir->i_sb;
 	unsigned chunk_size = ext2_chunk_size(dir);
 	char *kaddr = page_address(page);
 	u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
 	unsigned offs, rec_len;
-	unsigned limit = PAGE_CACHE_SIZE;
+	unsigned limit = page_cache_size(mapping);
 	ext2_dirent *p;
 	char *error;
 
-	if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
-		limit = dir->i_size & ~PAGE_CACHE_MASK;
+	if (page_cache_index(mapping, dir->i_size) == page->index) {
+		limit = page_cache_offset(mapping, dir->i_size);
 		if (limit & (chunk_size - 1))
 			goto Ebadsize;
 		if (!limit)
@@ -140,7 +143,7 @@ Einumber:
 bad_entry:
 	ext2_error (sb, "ext2_check_page", "bad entry in directory #%lu: %s - "
 		"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
-		dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
+		dir->i_ino, error, page_cache_pos(mapping, page->index, offs),
 		(unsigned long) le32_to_cpu(p->inode),
 		rec_len, p->name_len);
 	goto fail;
@@ -149,7 +152,7 @@ Eend:
 	ext2_error (sb, "ext2_check_page",
 		"entry in directory #%lu spans the page boundary"
 		"offset=%lu, inode=%lu",
-		dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
+		dir->i_ino, page_cache_pos(mapping, page->index, offs),
 		(unsigned long) le32_to_cpu(p->inode));
 fail:
 	SetPageChecked(page);
@@ -250,8 +253,9 @@ ext2_readdir (struct file * filp, void *
 	loff_t pos = filp->f_pos;
 	struct inode *inode = filp->f_path.dentry->d_inode;
 	struct super_block *sb = inode->i_sb;
-	unsigned int offset = pos & ~PAGE_CACHE_MASK;
-	unsigned long n = pos >> PAGE_CACHE_SHIFT;
+	struct address_space *mapping = inode->i_mapping;
+	unsigned int offset = page_cache_offset(mapping, pos);
+	unsigned long n = page_cache_index(mapping, pos);
 	unsigned long npages = dir_pages(inode);
 	unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
 	unsigned char *types = NULL;
@@ -272,14 +276,14 @@ ext2_readdir (struct file * filp, void *
 			ext2_error(sb, __FUNCTION__,
 				   "bad page in #%lu",
 				   inode->i_ino);
-			filp->f_pos += PAGE_CACHE_SIZE - offset;
+			filp->f_pos += page_cache_size(mapping) - offset;
 			return -EIO;
 		}
 		kaddr = page_address(page);
 		if (unlikely(need_revalidate)) {
 			if (offset) {
 				offset = ext2_validate_entry(kaddr, offset, chunk_mask);
-				filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
+				filp->f_pos = page_cache_pos(mapping, n, offset);
 			}
 			filp->f_version = inode->i_version;
 			need_revalidate = 0;
@@ -302,7 +306,7 @@ ext2_readdir (struct file * filp, void *
 
 				offset = (char *)de - kaddr;
 				over = filldir(dirent, de->name, de->name_len,
-						(n<<PAGE_CACHE_SHIFT) | offset,
+						page_cache_pos(mapping, n, offset),
 						le32_to_cpu(de->inode), d_type);
 				if (over) {
 					ext2_put_page(page);
@@ -328,6 +332,7 @@ struct ext2_dir_entry_2 * ext2_find_entr
 			struct dentry *dentry, struct page ** res_page)
 {
 	const char *name = dentry->d_name.name;
+	struct address_space *mapping = dir->i_mapping;
 	int namelen = dentry->d_name.len;
 	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
 	unsigned long start, n;
@@ -369,7 +374,7 @@ struct ext2_dir_entry_2 * ext2_find_entr
 		if (++n >= npages)
 			n = 0;
 		/* next page is past the blocks we've got */
-		if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
+		if (unlikely(n > (dir->i_blocks >> (page_cache_shift(mapping) - 9)))) {
 			ext2_error(dir->i_sb, __FUNCTION__,
 				"dir %lu size %lld exceeds block count %llu",
 				dir->i_ino, dir->i_size,
@@ -438,6 +443,7 @@ void ext2_set_link(struct inode *dir, st
 int ext2_add_link (struct dentry *dentry, struct inode *inode)
 {
 	struct inode *dir = dentry->d_parent->d_inode;
+	struct address_space *mapping = inode->i_mapping;
 	const char *name = dentry->d_name.name;
 	int namelen = dentry->d_name.len;
 	unsigned chunk_size = ext2_chunk_size(dir);
@@ -467,7 +473,7 @@ int ext2_add_link (struct dentry *dentry
 		kaddr = page_address(page);
 		dir_end = kaddr + ext2_last_byte(dir, n);
 		de = (ext2_dirent *)kaddr;
-		kaddr += PAGE_CACHE_SIZE - reclen;
+		kaddr += page_cache_size(mapping) - reclen;
 		while ((char *)de <= kaddr) {
 			if ((char *)de == dir_end) {
 				/* We hit i_size */
Index: linux-2.6.21-rc7/fs/ext2/ext2.h
===================================================================
--- linux-2.6.21-rc7.orig/fs/ext2/ext2.h	2007-04-23 22:26:18.000000000 -0700
+++ linux-2.6.21-rc7/fs/ext2/ext2.h	2007-04-23 22:27:52.000000000 -0700
@@ -160,6 +160,7 @@ extern const struct file_operations ext2
 /* file.c */
 extern const struct inode_operations ext2_file_inode_operations;
 extern const struct file_operations ext2_file_operations;
+extern const struct file_operations ext2_no_mmap_file_operations;
 extern const struct file_operations ext2_xip_file_operations;
 
 /* inode.c */
Index: linux-2.6.21-rc7/fs/ext2/file.c
===================================================================
--- linux-2.6.21-rc7.orig/fs/ext2/file.c	2007-04-23 22:26:18.000000000 -0700
+++ linux-2.6.21-rc7/fs/ext2/file.c	2007-04-23 22:27:52.000000000 -0700
@@ -58,6 +58,24 @@ const struct file_operations ext2_file_o
 	.splice_write	= generic_file_splice_write,
 };
 
+const struct file_operations ext2_no_mmap_file_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= do_sync_read,
+	.write		= do_sync_write,
+	.aio_read	= generic_file_aio_read,
+	.aio_write	= generic_file_aio_write,
+	.ioctl		= ext2_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= ext2_compat_ioctl,
+#endif
+	.open		= generic_file_open,
+	.release	= ext2_release_file,
+	.fsync		= ext2_sync_file,
+	.sendfile	= generic_file_sendfile,
+	.splice_read	= generic_file_splice_read,
+	.splice_write	= generic_file_splice_write,
+};
+
 #ifdef CONFIG_EXT2_FS_XIP
 const struct file_operations ext2_xip_file_operations = {
 	.llseek		= generic_file_llseek,
Index: linux-2.6.21-rc7/fs/ext2/inode.c
===================================================================
--- linux-2.6.21-rc7.orig/fs/ext2/inode.c	2007-04-23 22:26:18.000000000 -0700
+++ linux-2.6.21-rc7/fs/ext2/inode.c	2007-04-23 22:29:49.000000000 -0700
@@ -1128,10 +1128,16 @@ void ext2_read_inode (struct inode * ino
 			inode->i_fop = &ext2_xip_file_operations;
 		} else if (test_opt(inode->i_sb, NOBH)) {
 			inode->i_mapping->a_ops = &ext2_nobh_aops;
-			inode->i_fop = &ext2_file_operations;
+			if (mapping_order(inode->i_mapping))
+				inode->i_fop = &ext2_no_mmap_file_operations;
+			else
+				inode->i_fop = &ext2_file_operations;
 		} else {
 			inode->i_mapping->a_ops = &ext2_aops;
-			inode->i_fop = &ext2_file_operations;
+			if (mapping_order(inode->i_mapping))
+				inode->i_fop = &ext2_no_mmap_file_operations;
+			else
+				inode->i_fop = &ext2_file_operations;
 		}
 	} else if (S_ISDIR(inode->i_mode)) {
 		inode->i_op = &ext2_dir_inode_operations;
Index: linux-2.6.21-rc7/fs/ext2/namei.c
===================================================================
--- linux-2.6.21-rc7.orig/fs/ext2/namei.c	2007-04-23 22:26:18.000000000 -0700
+++ linux-2.6.21-rc7/fs/ext2/namei.c	2007-04-23 22:30:56.000000000 -0700
@@ -114,10 +114,16 @@ static int ext2_create (struct inode * d
 			inode->i_fop = &ext2_xip_file_operations;
 		} else if (test_opt(inode->i_sb, NOBH)) {
 			inode->i_mapping->a_ops = &ext2_nobh_aops;
-			inode->i_fop = &ext2_file_operations;
+			if (mapping_order(inode->i_mapping))
+				inode->i_fop = &ext2_no_mmap_file_operations;
+			else
+				inode->i_fop = &ext2_file_operations;
 		} else {
 			inode->i_mapping->a_ops = &ext2_aops;
-			inode->i_fop = &ext2_file_operations;
+			if (mapping_order(inode->i_mapping))
+				inode->i_fop = &ext2_no_mmap_file_operations;
+			else
+				inode->i_fop = &ext2_file_operations;
 		}
 		mark_inode_dirty(inode);
 		err = ext2_add_nondir(dentry, inode);

--