ext4: Add new "development flag" to the ext4 filesystem (469108ff) · Commits · 戴 / test

This flag is simply a generic "this is a crash/burn test filesystem" marker. If it is set, then filesystem code which is "in development" will be allowed to mount the filesystem. Filesystem code which is not considered ready for prime-time will check for this flag, and if it is not set, it will refuse to touch the filesystem. As we start rolling ext4 out to distro's like Fedora, et. al, this makes it less likely that a user might accidentally start using ext4 on a production filesystem; a bad thing, since that will essentially make it be unfsckable until e2fsprogs catches up. Signed-off-by:

Theodore Tso <tytso@MIT.EDU> Signed-off-by:

Mingming Cao <cmm@us.ibm.com>

fs/ext4/super.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -1919,6 +1919,17 @@ static int ext4_fill_super (struct super_block sb, void data, int silent)
		printk(KERN_WARNING
		"EXT4-fs warning: feature flags set on rev 0 fs, "
		"running e2fsck is recommended\n");

		/*
		* Since ext4 is still considered development code, we require
		* that the TEST_FILESYS flag in s->flags be set.
		*/
		if (!(le32_to_cpu(es->s_flags) & EXT2_FLAGS_TEST_FILESYS)) {
		printk(KERN_WARNING "EXT4-fs: %s: not marked "
		"OK to use with test code.\n", sb->s_id);
		goto failed_mount;
		}

		/*
		* Check feature flags regardless of the revision level, since we
		* previously didn't change the revision level when setting the flags,

include/linux/ext4_fs.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -489,6 +489,13 @@ do { \
		#define EXT4_ERROR_FS 0x0002 /* Errors detected */
		#define EXT4_ORPHAN_FS 0x0004 /* Orphans being recovered */

		/*
		* Misc. filesystem flags
		*/
		#define EXT2_FLAGS_SIGNED_HASH 0x0001 /* Signed dirhash in use */
		#define EXT2_FLAGS_UNSIGNED_HASH 0x0002 /* Unsigned dirhash in use */
		#define EXT2_FLAGS_TEST_FILESYS 0x0004 /* to test development code */

		/*
		* Mount flags
		*/

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