Theodore Ts'o wrote: > In fs/Makefile, ext3 was placed before ext2 so that a root filesystem > that possessed a journal, it would be mounted as ext3 instead of ext2. > This was necessary because a cleanly unmounted ext3 filesystem was > fully backwards compatible with ext2, and could be mounted by ext2 --- > but it was desirable that it be mounted with ext3 so that the > journaling would be enabled. > > The ext4 filesystem supports new incompatible features, so there is no > danger of an ext4 filesystem being mistaken for an ext2 filesystem. > However, ordering didn't matter until ext4 gained the ability to mount > filesystems without a journal. Now that this is the case, given that > ext4 is before ext2, it means that root filesystems that were only > using the plain-jane ext2 format are getting mounted using the ext4 > filesystem driver, which is a change in behavior which could be > surprising to users > > It's doubtful that there are that many ext2-only root filesystem users > that would also have ext4 compiled into the kernel, but to adhere to > the principle of least surprise, the correct ordering in fs/Makefile > is ext3, followed by ext2, and finally ext4. > > Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx> > --- > fs/Makefile | 6 ++++-- > 1 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/fs/Makefile b/fs/Makefile > index 38bc735..21c2f50 100644 > --- a/fs/Makefile > +++ b/fs/Makefile > @@ -69,10 +69,12 @@ obj-$(CONFIG_DLM) += dlm/ > # Do not add any filesystems before this line > obj-$(CONFIG_REISERFS_FS) += reiserfs/ > obj-$(CONFIG_EXT3_FS) += ext3/ # Before ext2 so root fs can be ext3 > -obj-$(CONFIG_EXT4_FS) += ext4/ # Before ext2 so root fs can be ext4 > +obj-$(CONFIG_EXT2_FS) += ext2/ > +# We place ext4 after ext2 so plain ext2 root fs's are mounted using ext4 > +# unless explicitly requested by rootfstype Shouldn't that be "aren't mounted using ext4..." ? -Eric > +obj-$(CONFIG_EXT4_FS) += ext4/ > obj-$(CONFIG_JBD) += jbd/ > obj-$(CONFIG_JBD2) += jbd2/ > -obj-$(CONFIG_EXT2_FS) += ext2/ > obj-$(CONFIG_CRAMFS) += cramfs/ > obj-$(CONFIG_SQUASHFS) += squashfs/ > obj-y += ramfs/ -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
