ext4: add mext_check_validity() to do basic check

Currently, the basic validation checks during the move extent operation
are scattered across __ext4_ioctl() and ext4_move_extents(), which makes
the code somewhat disorganized. Introduce a new helper,
mext_check_validity(), to handle these checks. This change involves only
code relocation without any logical modifications.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-ID: <20251013015128.499308-7-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 65 insertions, 37 deletions

diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 6175906c7119..cdd175d5c1f3 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -442,6 +442,68 @@ repair_branches:
 	goto unlock_folios;
 }
 
+/*
+ * Check the validity of the basic filesystem environment and the
+ * inodes' support status.
+ */
+static int mext_check_validity(struct inode *orig_inode,
+			       struct inode *donor_inode)
+{
+	struct super_block *sb = orig_inode->i_sb;
+
+	/* origin and donor should be different inodes */
+	if (orig_inode == donor_inode) {
+		ext4_debug("ext4 move extent: The argument files should not be same inode [ino:orig %lu, donor %lu]\n",
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -EINVAL;
+	}
+
+	/* origin and donor should belone to the same filesystem */
+	if (orig_inode->i_sb != donor_inode->i_sb) {
+		ext4_debug("ext4 move extent: The argument files should be in same FS [ino:orig %lu, donor %lu]\n",
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -EINVAL;
+	}
+
+	/* Regular file check */
+	if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
+		ext4_debug("ext4 move extent: The argument files should be regular file [ino:orig %lu, donor %lu]\n",
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -EINVAL;
+	}
+
+	if (ext4_has_feature_bigalloc(sb)) {
+		ext4_msg(sb, KERN_ERR,
+			 "Online defrag not supported with bigalloc");
+		return -EOPNOTSUPP;
+	}
+
+	if (IS_DAX(orig_inode)) {
+		ext4_msg(sb, KERN_ERR,
+			 "Online defrag not supported with DAX");
+		return -EOPNOTSUPP;
+	}
+
+	/*
+	 * TODO: it's not obvious how to swap blocks for inodes with full
+	 * journaling enabled.
+	 */
+	if (ext4_should_journal_data(orig_inode) ||
+	    ext4_should_journal_data(donor_inode)) {
+		ext4_msg(sb, KERN_ERR,
+			 "Online defrag not supported with data journaling");
+		return -EOPNOTSUPP;
+	}
+
+	if (IS_ENCRYPTED(orig_inode) || IS_ENCRYPTED(donor_inode)) {
+		ext4_msg(sb, KERN_ERR,
+			 "Online defrag not supported for encrypted files");
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
 /**
  * mext_check_arguments - Check whether move extent can be done
  *
@@ -567,43 +629,9 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
 	ext4_lblk_t d_start = donor_blk;
 	int ret;
 
-	if (orig_inode->i_sb != donor_inode->i_sb) {
-		ext4_debug("ext4 move extent: The argument files "
-			"should be in same FS [ino:orig %lu, donor %lu]\n",
-			orig_inode->i_ino, donor_inode->i_ino);
-		return -EINVAL;
-	}
-
-	/* orig and donor should be different inodes */
-	if (orig_inode == donor_inode) {
-		ext4_debug("ext4 move extent: The argument files should not "
-			"be same inode [ino:orig %lu, donor %lu]\n",
-			orig_inode->i_ino, donor_inode->i_ino);
-		return -EINVAL;
-	}
-
-	/* Regular file check */
-	if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
-		ext4_debug("ext4 move extent: The argument files should be "
-			"regular file [ino:orig %lu, donor %lu]\n",
-			orig_inode->i_ino, donor_inode->i_ino);
-		return -EINVAL;
-	}
-
-	/* TODO: it's not obvious how to swap blocks for inodes with full
-	   journaling enabled */
-	if (ext4_should_journal_data(orig_inode) ||
-	    ext4_should_journal_data(donor_inode)) {
-		ext4_msg(orig_inode->i_sb, KERN_ERR,
-			 "Online defrag not supported with data journaling");
-		return -EOPNOTSUPP;
-	}
-
-	if (IS_ENCRYPTED(orig_inode) || IS_ENCRYPTED(donor_inode)) {
-		ext4_msg(orig_inode->i_sb, KERN_ERR,
-			 "Online defrag not supported for encrypted files");
-		return -EOPNOTSUPP;
-	}
+	ret = mext_check_validity(orig_inode, donor_inode);
+	if (ret)
+		return ret;
 
 	/* Protect orig and donor inodes against a truncate */
 	lock_two_nondirectories(orig_inode, donor_inode);