linux-ext4 - Re: [PATCH 3/7] ext2fs: Update allocation info earlier in ext2fs_mkdir() and ext2fs

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Date:   Sun, 15 Mar 2020 12:15:09 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Jan Kara <jack@...e.cz>
Cc:     linux-ext4@...r.kernel.org
Subject: Re: [PATCH 3/7] ext2fs: Update allocation info earlier in
 ext2fs_mkdir() and ext2fs_symlink()

Ah, I see now why this patch is needed.  If we don't update the block
allocation bitmap to indicate block has been taken, and there is a
need to allocate an htree index block, we will end up allocating the
same block twice.

Thanks, I've applied this patch with the following added.

     	     	  	     	 	   - Ted

diff --git a/lib/ext2fs/mkdir.c b/lib/ext2fs/mkdir.c
index 947003eb..437c8ffc 100644
--- a/lib/ext2fs/mkdir.c
+++ b/lib/ext2fs/mkdir.c
@@ -43,6 +43,7 @@ errcode_t ext2fs_mkdir(ext2_filsys fs, ext2_ino_t parent, ext2_ino_t inum,
 	blk64_t			blk;
 	char			*block = 0;
 	int			inline_data = 0;
+	int			drop_refcount = 0;
 
 	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 
@@ -149,6 +150,7 @@ errcode_t ext2fs_mkdir(ext2_filsys fs, ext2_ino_t parent, ext2_ino_t inum,
 	if (!inline_data)
 		ext2fs_block_alloc_stats2(fs, blk, +1);
 	ext2fs_inode_alloc_stats2(fs, ino, +1, 1);
+	drop_refcount = 1;
 
 	/*
 	 * Link the directory into the filesystem hierarchy
@@ -181,10 +183,16 @@ errcode_t ext2fs_mkdir(ext2_filsys fs, ext2_ino_t parent, ext2_ino_t inum,
 		if (retval)
 			goto cleanup;
 	}
+	drop_refcount = 0;
 
 cleanup:
 	if (block)
 		ext2fs_free_mem(&block);
+	if (drop_refcount) {
+		if (!inline_data)
+			ext2fs_block_alloc_stats2(fs, blk, -1);
+		ext2fs_inode_alloc_stats2(fs, ino, -1, 1);
+	}
 	return retval;
 
 }
diff --git a/lib/ext2fs/symlink.c b/lib/ext2fs/symlink.c
index 3e07a539..a66fb7ec 100644
--- a/lib/ext2fs/symlink.c
+++ b/lib/ext2fs/symlink.c
@@ -54,6 +54,7 @@ errcode_t ext2fs_symlink(ext2_filsys fs, ext2_ino_t parent, ext2_ino_t ino,
 	int			fastlink, inlinelink;
 	unsigned int		target_len;
 	char			*block_buf = 0;
+	int			drop_refcount = 0;
 
 	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 
@@ -168,6 +169,7 @@ need_block:
 	if (!fastlink && !inlinelink)
 		ext2fs_block_alloc_stats2(fs, blk, +1);
 	ext2fs_inode_alloc_stats2(fs, ino, +1, 0);
+	drop_refcount = 1;
 
 	/*
 	 * Link the symlink into the filesystem hierarchy
@@ -185,10 +187,16 @@ need_block:
 		if (retval)
 			goto cleanup;
 	}
+	drop_refcount = 0;
 
 cleanup:
 	if (block_buf)
 		ext2fs_free_mem(&block_buf);
+	if (drop_refcount) {
+		if (!fastlink && !inlinelink)
+			ext2fs_block_alloc_stats2(fs, blk, -1);
+		ext2fs_inode_alloc_stats2(fs, ino, -1, 0);
+	}
 	return retval;
 }