[PATCH 4/4] ext4: allow large folios and bs > ps encryption

[Baokun Li]

ext4 refuses encryption when the block size exceeds the page size
in three places: at mount time (ext4_check_large_folio()),
in ext4_set_context(), and in __ext4_iget().

Sub-block data units are now enabled by default, so encryption
works on a filesystem whose block size exceeds the page size.
Remove the three checks; stable trees should keep them and
not backport this feature.

ext4_set_max_mapping_order() now runs on every mount, and
the preceding patch routes a folio that crosses a DUN wraparound
to the buffer_head path. Encrypted files therefore get the same
large folio orders as unencrypted files, including when block size
is larger than page size.

Signed-off-by: Baokun Li <libaokun@xxxxxxxxxxxxxxxxx>
---
 fs/ext4/crypto.c |  9 ---------
 fs/ext4/inode.c  |  6 ------
 fs/ext4/super.c  | 22 +---------------------
 3 files changed, 1 insertion(+), 36 deletions(-)

diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index 318b2eaea741..1a0fccb084ef 100644
--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -156,15 +156,6 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
 	if (ext4_test_inode_flag(inode, EXT4_INODE_DAX))
 		return -EOPNOTSUPP;
 
-	/*
-	 * Encryption is not supported when the block size is larger
-	 * than the page size.  This is rejected at mount time by
-	 * ext4_check_large_folio(), and this check here is for the case
-	 * when the 'encrypt' feature is enabled on a mounted filesystem.
-	 */
-	if (inode->i_sb->s_blocksize > PAGE_SIZE)
-		return -EOPNOTSUPP;
-
 	res = ext4_convert_inline_data(inode);
 	if (res)
 		return res;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 10cd85d4c721..b4d581aa5ee1 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -6571,12 +6571,6 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
 		ret = -EFSCORRUPTED;
 		goto bad_inode;
 	}
-	if (IS_ENCRYPTED(inode) && sb->s_blocksize > PAGE_SIZE) {
-		ext4_error_inode(inode, function, line, 0,
-				 "encrypted inode with block size larger than page size");
-		ret = -EFSCORRUPTED;
-		goto bad_inode;
-	}
 
 	ext4_set_inode_mapping_order(inode);
 
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9cae52471dee..ba2d2e184d3a 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5165,24 +5165,6 @@ static void ext4_set_max_mapping_order(struct super_block *sb)
 		sbi->s_max_folio_order = EXT4_MAX_PAGECACHE_ORDER(sb);
 }
 
-static int ext4_check_large_folio(struct super_block *sb)
-{
-	const char *err_str = NULL;
-
-	if (ext4_has_feature_encrypt(sb))
-		err_str = "encrypt";
-
-	if (!err_str) {
-		ext4_set_max_mapping_order(sb);
-	} else if (sb->s_blocksize > PAGE_SIZE) {
-		ext4_msg(sb, KERN_ERR, "bs(%lu) > ps(%lu) unsupported for %s",
-			 sb->s_blocksize, PAGE_SIZE, err_str);
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
 static int ext4_load_super(struct super_block *sb, ext4_fsblk_t *lsb,
 			   int silent)
 {
@@ -5461,9 +5443,7 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 
 	ext4_apply_options(fc, sb);
 
-	err = ext4_check_large_folio(sb);
-	if (err < 0)
-		goto failed_mount;
+	ext4_set_max_mapping_order(sb);
 
 	err = ext4_encoding_init(sb, es);
 	if (err)
-- 
2.43.7