From 5fef457767fa876e29a5277e6c7428aa36c9ac61 Mon Sep 17 00:00:00 2001

From: Theodore Ts'o <tytso@mit.edu>

Date: Thu, 13 Dec 2018 00:51:51 -0500

Subject: [PATCH 1/4] libext2fs: add ext2fs_{read,write}_inode2()

Add new library interface which allows the caller to control whether

the inode checksum should be checked on inode read, or set on inode

write.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

---

 lib/ext2fs/ext2fs.h | 18 +++++++++++++++-

 lib/ext2fs/inode.c  | 50 +++++++++++++++++++++++++++++----------------

 2 files changed, 49 insertions(+), 19 deletions(-)

diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h

index c86596a6..96735c8e 100644

--- a/lib/ext2fs/ext2fs.h

+++ b/lib/ext2fs/ext2fs.h

@@ -570,6 +570,16 @@ typedef struct ext2_icount *ext2_icount_t;

  */

 #define BMAP_RET_UNINIT	0x0001

+/*

+ * Flags for ext2fs_read_inode2

+ */

+#define READ_INODE_NOCSUM	0x0001

+

+/*

+ * Flags for ext2fs_write_inode2

+ */

+#define WRITE_INODE_NOCSUM	0x0001

+

 /*

  * Flags for imager.c functions

  */

@@ -1514,13 +1524,19 @@ extern int ext2fs_inode_scan_flags(ext2_inode_scan scan, int set_flags,

 extern errcode_t ext2fs_read_inode_full(ext2_filsys fs, ext2_ino_t ino,

 					struct ext2_inode * inode,

 					int bufsize);

-extern errcode_t ext2fs_read_inode (ext2_filsys fs, ext2_ino_t ino,

+extern errcode_t ext2fs_read_inode(ext2_filsys fs, ext2_ino_t ino,

 			    struct ext2_inode * inode);

+extern errcode_t ext2fs_read_inode2(ext2_filsys fs, ext2_ino_t ino,

+				    struct ext2_inode * inode,

+				    int bufsize, int flags);

 extern errcode_t ext2fs_write_inode_full(ext2_filsys fs, ext2_ino_t ino,

 					 struct ext2_inode * inode,

 					 int bufsize);

 extern errcode_t ext2fs_write_inode(ext2_filsys fs, ext2_ino_t ino,

 			    struct ext2_inode * inode);

+extern errcode_t ext2fs_write_inode2(ext2_filsys fs, ext2_ino_t ino,

+				     struct ext2_inode * inode,

+				     int bufsize, int flags);

 extern errcode_t ext2fs_write_new_inode(ext2_filsys fs, ext2_ino_t ino,

 			    struct ext2_inode * inode);

 extern errcode_t ext2fs_get_blocks(ext2_filsys fs, ext2_ino_t ino, blk_t *blocks);

diff --git a/lib/ext2fs/inode.c b/lib/ext2fs/inode.c

index 013c658e..2a4be739 100644

--- a/lib/ext2fs/inode.c

+++ b/lib/ext2fs/inode.c

@@ -740,8 +740,9 @@ errcode_t ext2fs_get_next_inode(ext2_inode_scan scan, ext2_ino_t *ino,

 /*

  * Functions to read and write a single inode.

  */

-errcode_t ext2fs_read_inode_full(ext2_filsys fs, ext2_ino_t ino,

-				 struct ext2_inode * inode, int bufsize)

+errcode_t ext2fs_read_inode2(ext2_filsys fs, ext2_ino_t ino,

+			     struct ext2_inode * inode, int bufsize,

+			     int flags)

 {

 	blk64_t		block_nr;

 	dgrp_t		group;

@@ -850,21 +851,29 @@ errcode_t ext2fs_read_inode_full(ext2_filsys fs, ext2_ino_t ino,

 	}

 	memcpy(inode, iptr, (bufsize > length) ? length : bufsize);

-	if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) && fail_csum)

+	if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) &&

+	    !(flags & READ_INODE_NOCSUM) && fail_csum)

 		return EXT2_ET_INODE_CSUM_INVALID;

 	return 0;

 }

+errcode_t ext2fs_read_inode_full(ext2_filsys fs, ext2_ino_t ino,

+				 struct ext2_inode * inode, int bufsize)

+{

+	return ext2fs_read_inode2(fs, ino, inode, bufsize, 0);

+}

+

 errcode_t ext2fs_read_inode(ext2_filsys fs, ext2_ino_t ino,

 			    struct ext2_inode * inode)

 {

-	return ext2fs_read_inode_full(fs, ino, inode,

-					sizeof(struct ext2_inode));

+	return ext2fs_read_inode2(fs, ino, inode,

+				  sizeof(struct ext2_inode), 0);

 }

-errcode_t ext2fs_write_inode_full(ext2_filsys fs, ext2_ino_t ino,

-				  struct ext2_inode * inode, int bufsize)

+errcode_t ext2fs_write_inode2(ext2_filsys fs, ext2_ino_t ino,

+			      struct ext2_inode * inode, int bufsize,

+			      int flags)

 {

 	blk64_t block_nr;

 	dgrp_t group;

@@ -895,12 +904,9 @@ errcode_t ext2fs_write_inode_full(ext2_filsys fs, ext2_ino_t ino,

 	if (bufsize < length) {

 		int old_flags = fs->flags;

-		fs->flags |= EXT2_FLAG_IGNORE_CSUM_ERRORS;

-		retval = ext2fs_read_inode_full(fs, ino,

-						(struct ext2_inode *)w_inode,

-						length);

-		fs->flags = (old_flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) |

-			    (fs->flags & ~EXT2_FLAG_IGNORE_CSUM_ERRORS);

+		retval = ext2fs_read_inode2(fs, ino,

+					    (struct ext2_inode *)w_inode,

+					    length, READ_INODE_NOCSUM);

 		if (retval)

 			goto errout;

 	}

@@ -930,9 +936,11 @@ errcode_t ext2fs_write_inode_full(ext2_filsys fs, ext2_ino_t ino,

 	ext2fs_swap_inode_full(fs, w_inode, w_inode, 1, length);

 #endif

-	retval = ext2fs_inode_csum_set(fs, ino, w_inode);

-	if (retval)

-		goto errout;

+	if ((flags & WRITE_INODE_NOCSUM) == 0) {

+		retval = ext2fs_inode_csum_set(fs, ino, w_inode);

+		if (retval)

+			goto errout;

+	}

 	group = (ino - 1) / EXT2_INODES_PER_GROUP(fs->super);

 	offset = ((ino - 1) % EXT2_INODES_PER_GROUP(fs->super)) *

@@ -989,11 +997,17 @@ errout:

 	return retval;

 }

+errcode_t ext2fs_write_inode_full(ext2_filsys fs, ext2_ino_t ino,

+				  struct ext2_inode * inode, int bufsize)

+{

+	return ext2fs_write_inode2(fs, ino, inode, bufsize, 0);

+}

+

 errcode_t ext2fs_write_inode(ext2_filsys fs, ext2_ino_t ino,

 			     struct ext2_inode *inode)

 {

-	return ext2fs_write_inode_full(fs, ino, inode,

-				       sizeof(struct ext2_inode));

+	return ext2fs_write_inode2(fs, ino, inode,

+				   sizeof(struct ext2_inode), 0);

 }

 /*

-- 

2.20.1