[PATCH 3/3] fs: ext4: Support transparent compression

[Tom Marshall <tom@cyngn.com>]

Signed-off-by: Tom Marshall <tdm@cyngn.com>
---
 fs/ext4/Makefile |  4 ++++
 fs/ext4/ext4.h   |  4 ++++
 fs/ext4/inode.c  | 41 +++++++++++++++++++++++++++++++++++++++--
 3 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
index 75285ea..b6e230a 100644
--- a/fs/ext4/Makefile
+++ b/fs/ext4/Makefile
@@ -14,3 +14,7 @@ ext4-$(CONFIG_EXT4_FS_POSIX_ACL)	+= acl.o
 ext4-$(CONFIG_EXT4_FS_SECURITY)		+= xattr_security.o
 ext4-$(CONFIG_EXT4_FS_ENCRYPTION)	+= crypto_policy.o crypto.o \
 		crypto_key.o crypto_fname.o
+
+ifdef CONFIG_FS_TRANSPARENT_COMPRESSION
+ccflags-y += -DFS_IMPL
+endif
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 9a83f14..88d14f6 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -32,6 +32,7 @@
 #include <linux/ratelimit.h>
 #include <crypto/hash.h>
 #include <linux/falloc.h>
+#include <linux/fs-xcomp.h>
 #ifdef __KERNEL__
 #include <linux/compat.h>
 #endif
@@ -957,6 +958,9 @@ struct ext4_inode_info {
 	/* Encryption params */
 	struct ext4_encryption_key i_encryption_key;
 #endif
+#ifdef CONFIG_FS_TRANSPARENT_COMPRESSION
+	struct xcomp_inode_info i_xcomp_info;
+#endif
 };
 
 /*
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0554b0b..9077415 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -46,6 +46,13 @@
 
 #define MPAGE_DA_EXTENT_TAIL 0x01
 
+static int ext4_inode_is_compressed(struct inode *inode)
+{
+	if (!xcomp_enabled())
+		return 0;
+	return (EXT4_I(inode)->i_flags & EXT4_COMPR_FL);
+}
+
 static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
 			      struct ext4_inode_info *ei)
 {
@@ -250,6 +257,11 @@ void ext4_evict_inode(struct inode *inode)
 
 	if (IS_SYNC(inode))
 		ext4_handle_sync(handle);
+
+	if (ext4_inode_is_compressed(inode)) {
+		xcomp_inode_info_free(&EXT4_I(inode)->i_xcomp_info);
+	}
+
 	inode->i_size = 0;
 	err = ext4_mark_inode_dirty(handle, inode);
 	if (err) {
@@ -2912,7 +2924,7 @@ static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
 	return generic_block_bmap(mapping, block, ext4_get_block);
 }
 
-static int ext4_readpage(struct file *file, struct page *page)
+static int __ext4_readpage(struct page *page)
 {
 	int ret = -EAGAIN;
 	struct inode *inode = page->mapping->host;
@@ -2928,8 +2940,16 @@ static int ext4_readpage(struct file *file, struct page *page)
 	return ret;
 }
 
+static int ext4_readpage(struct file *file, struct page *page)
+{
+	if (ext4_inode_is_compressed(page->mapping->host))
+		return xcomp_readpage(&EXT4_I(page->mapping->host)->i_xcomp_info, page);
+
+	return __ext4_readpage(page);
+}
+
 static int
-ext4_readpages(struct file *file, struct address_space *mapping,
+__ext4_readpages(struct address_space *mapping,
 		struct list_head *pages, unsigned nr_pages)
 {
 	struct inode *inode = mapping->host;
@@ -2941,6 +2961,16 @@ ext4_readpages(struct file *file, struct address_space *mapping,
 	return ext4_mpage_readpages(mapping, pages, NULL, nr_pages);
 }
 
+static int
+ext4_readpages(struct file *file, struct address_space *mapping,
+		struct list_head *pages, unsigned nr_pages)
+{
+	if (ext4_inode_is_compressed(mapping->host))
+		return xcomp_readpages(&EXT4_I(mapping->host)->i_xcomp_info, mapping, pages, nr_pages);
+
+	return __ext4_readpages(mapping, pages, nr_pages);
+}
+
 static void ext4_invalidatepage(struct page *page, unsigned int offset,
 				unsigned int length)
 {
@@ -4117,6 +4147,9 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
 		ei->i_file_acl |=
 			((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
 	inode->i_size = ext4_isize(raw_inode);
+#ifdef CONFIG_FS_TRANSPARENT_COMPRESSION
+	inode->i_compressed_size = inode->i_size;
+#endif
 	ei->i_disksize = inode->i_size;
 #ifdef CONFIG_QUOTA
 	ei->i_reserved_quota = 0;
@@ -4241,6 +4274,10 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
 	brelse(iloc.bh);
 	ext4_set_inode_flags(inode);
 	unlock_new_inode(inode);
+
+	if (S_ISREG(inode->i_mode) && ext4_inode_is_compressed(inode))
+		xcomp_inode_info_init(inode, &ei->i_xcomp_info, __ext4_readpage);
+
 	return inode;
 
 bad_inode:
-- 
2.1.4