1 files changed, 132 insertions, 52 deletions

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 2a822d30e73f..b5f184493c57 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -31,6 +31,42 @@
 #include "xattr.h"
 #include "acl.h"
 
+#ifdef CONFIG_FS_DAX
+static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	ssize_t ret;
+
+	inode_lock_shared(inode);
+	/*
+	 * Recheck under inode lock - at this point we are sure it cannot
+	 * change anymore
+	 */
+	if (!IS_DAX(inode)) {
+		inode_unlock_shared(inode);
+		/* Fallback to buffered IO in case we cannot support DAX */
+		return generic_file_read_iter(iocb, to);
+	}
+	ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
+	inode_unlock_shared(inode);
+
+	file_accessed(iocb->ki_filp);
+	return ret;
+}
+#endif
+
+static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	if (!iov_iter_count(to))
+		return 0; /* skip atime */
+
+#ifdef CONFIG_FS_DAX
+	if (IS_DAX(file_inode(iocb->ki_filp)))
+		return ext4_dax_read_iter(iocb, to);
+#endif
+	return generic_file_read_iter(iocb, to);
+}
+
 /*
  * Called when an inode is released. Note that this is different
  * from ext4_file_open: open gets called at every open, but release
@@ -88,6 +124,86 @@ ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
 	return 0;
 }
 
+/* Is IO overwriting allocated and initialized blocks? */
+static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
+{
+	struct ext4_map_blocks map;
+	unsigned int blkbits = inode->i_blkbits;
+	int err, blklen;
+
+	if (pos + len > i_size_read(inode))
+		return false;
+
+	map.m_lblk = pos >> blkbits;
+	map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
+	blklen = map.m_len;
+
+	err = ext4_map_blocks(NULL, inode, &map, 0);
+	/*
+	 * 'err==len' means that all of the blocks have been preallocated,
+	 * regardless of whether they have been initialized or not. To exclude
+	 * unwritten extents, we need to check m_flags.
+	 */
+	return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
+}
+
+static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	ssize_t ret;
+
+	ret = generic_write_checks(iocb, from);
+	if (ret <= 0)
+		return ret;
+	/*
+	 * If we have encountered a bitmap-format file, the size limit
+	 * is smaller than s_maxbytes, which is for extent-mapped files.
+	 */
+	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
+		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
+		if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
+			return -EFBIG;
+		iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
+	}
+	return iov_iter_count(from);
+}
+
+#ifdef CONFIG_FS_DAX
+static ssize_t
+ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	ssize_t ret;
+	bool overwrite = false;
+
+	inode_lock(inode);
+	ret = ext4_write_checks(iocb, from);
+	if (ret <= 0)
+		goto out;
+	ret = file_remove_privs(iocb->ki_filp);
+	if (ret)
+		goto out;
+	ret = file_update_time(iocb->ki_filp);
+	if (ret)
+		goto out;
+
+	if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) {
+		overwrite = true;
+		downgrade_write(&inode->i_rwsem);
+	}
+	ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
+out:
+	if (!overwrite)
+		inode_unlock(inode);
+	else
+		inode_unlock_shared(inode);
+	if (ret > 0)
+		ret = generic_write_sync(iocb, ret);
+	return ret;
+}
+#endif
+
 static ssize_t
 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
@@ -97,8 +213,13 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	int overwrite = 0;
 	ssize_t ret;
 
+#ifdef CONFIG_FS_DAX
+	if (IS_DAX(inode))
+		return ext4_dax_write_iter(iocb, from);
+#endif
+
 	inode_lock(inode);
-	ret = generic_write_checks(iocb, from);
+	ret = ext4_write_checks(iocb, from);
 	if (ret <= 0)
 		goto out;
 
@@ -114,53 +235,11 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		ext4_unwritten_wait(inode);
 	}
 
-	/*
-	 * If we have encountered a bitmap-format file, the size limit
-	 * is smaller than s_maxbytes, which is for extent-mapped files.
-	 */
-	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
-		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
-
-		if (iocb->ki_pos >= sbi->s_bitmap_maxbytes) {
-			ret = -EFBIG;
-			goto out;
-		}
-		iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
-	}
-
 	iocb->private = &overwrite;
-	if (o_direct) {
-		size_t length = iov_iter_count(from);
-		loff_t pos = iocb->ki_pos;
-
-		/* check whether we do a DIO overwrite or not */
-		if (ext4_should_dioread_nolock(inode) && !unaligned_aio &&
-		    pos + length <= i_size_read(inode)) {
-			struct ext4_map_blocks map;
-			unsigned int blkbits = inode->i_blkbits;
-			int err, len;
-
-			map.m_lblk = pos >> blkbits;
-			map.m_len = EXT4_MAX_BLOCKS(length, pos, blkbits);
-			len = map.m_len;
-
-			err = ext4_map_blocks(NULL, inode, &map, 0);
-			/*
-			 * 'err==len' means that all of blocks has
-			 * been preallocated no matter they are
-			 * initialized or not.  For excluding
-			 * unwritten extents, we need to check
-			 * m_flags.  There are two conditions that
-			 * indicate for initialized extents.  1) If we
-			 * hit extent cache, EXT4_MAP_MAPPED flag is
-			 * returned; 2) If we do a real lookup,
-			 * non-flags are returned.  So we should check
-			 * these two conditions.
-			 */
-			if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
-				overwrite = 1;
-		}
-	}
+	/* Check whether we do a DIO overwrite or not */
+	if (o_direct && ext4_should_dioread_nolock(inode) && !unaligned_aio &&
+	    ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from)))
+		overwrite = 1;
 
 	ret = __generic_file_write_iter(iocb, from);
 	inode_unlock(inode);
@@ -196,7 +275,7 @@ static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	if (IS_ERR(handle))
 		result = VM_FAULT_SIGBUS;
 	else
-		result = dax_fault(vma, vmf, ext4_dax_get_block);
+		result = dax_iomap_fault(vma, vmf, &ext4_iomap_ops);
 
 	if (write) {
 		if (!IS_ERR(handle))
@@ -230,9 +309,10 @@ static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
 
 	if (IS_ERR(handle))
 		result = VM_FAULT_SIGBUS;
-	else
-		result = dax_pmd_fault(vma, addr, pmd, flags,
-					 ext4_dax_get_block);
+	else {
+		result = dax_iomap_pmd_fault(vma, addr, pmd, flags,
+					     &ext4_iomap_ops);
+	}
 
 	if (write) {
 		if (!IS_ERR(handle))
@@ -687,7 +767,7 @@ loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 
 const struct file_operations ext4_file_operations = {
 	.llseek		= ext4_llseek,
-	.read_iter	= generic_file_read_iter,
+	.read_iter	= ext4_file_read_iter,
 	.write_iter	= ext4_file_write_iter,
 	.unlocked_ioctl = ext4_ioctl,
 #ifdef CONFIG_COMPAT