Linux 2.1.93

Linux 2.1.93

2.1.93 is out there. It is broken on other platforms than x86, because I
had to move some initialization code around, but this shoul dbe very easy
to fix (moving the device init code later makes a _lot_ of things easier:
the system is essentially up and running, and "kmalloc()" etc actually
works).

Now the PCI init code actually has the full SMP knowledge, which it needs
in order to get the interrupt mapping stuff right (for example - it might
eventually need it for other reasons too).

The PCI code has generally been cleaned up - thanks to Martin Mares (the
PCI cleanup is what forced me to do the other changes - anything else
would simply have been too ugly).

2.1.93 should also fix the stupid things in 92 (modules don't load due to
missing symbols, and NULL pointer dereferences in /proc under certain
circumstances etc).

The kernel should also be better at detecting the really low memory
circumstances, and eventually return NULL instead of just looping forever
trying to find a page that it won't ever find.

                        Linus

[tytso on ext2fs changes:]
These patches provide the following enhancements to ext2.
        * Fixed a bug where we weren't byte-swapping the feature set
                flags before checking EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER
        * Added Stephen Tweedie's patches to allow the number of file
                blocks which will be preallocated to be tuned (instead
                of being fixed at 8 blocks).
        * Added Stephen Tweedie's patches to allow directory blocks to
                be preallocated.  This change is only activated if the
                EXT2_FEATURE_COMPAT_DIR_PREALLOC is enabled.  (There
                will soon be a new release of e2fsprogs that will
                allow you to turn this on.)  The change is compatible
                with older kernels (that's why it's a COMPAT feature),
                but we need to flag it in the feature set because the
                e2fsck needs a few changes to support this.
        * Added future support for B-trees in directories.  I have a
                design in mind which is fully read/only compatible
                with the existing ext2 directories, which will make
                its debut in the 2.3 kernel series.  This patch will
                allow 2.2 kernels to mount filesystems with B-tree
                directories read-write; if a 2.2 kernel tries to
                modify a B-tree directory, the B-tree valid bit will
                be turned off, since the B-tree structures won't be
                updated by 2.2 kernels.  2.0 kernels will be able to
                mount filesystems with B-tree directories read-only.
                This defines a new feature, EXT2_FEATURE_RO_COMPAT_BTREE_DIR.
        * Added Jakub Jelinek's support for large files on 64-bit
                platforms.  On a 64-bit platform, the first time you
                expand a file past the 32-bit boundary, the
                EXT2_FEATURE_RO_COMPAT_LARGE_FILE is turned on.
                2.0 machines will be able to mount such filesystems
                read-only.  2.2 kernels on 32-bit platforms will be
                able such filesystems read-write, but they will only
                be able to see the first 2**32 bytes of the file, and
                any attempt to open a large file for read/write access
                will cause an EBIGF error.
        * Added support for storing the file type in the directory
                entry.  This optimization was added to BSD 4.4 and
                makes a very big difference for a number of
                operations, since application programs can avoid doing
                a stat in a number of situations.  Support for this is
                in the GNU user-land utilities, and is in glibc
                already.  Beyond this patch, we also need to implement
                a new getdents system call that will return the
                information all the way to libc.
                The reason why it's important to get this change into
                2.2 is that it requires "stealing" 8-bits from the
                name_len field of the directory entry.  Ext2fs limits
                you to 255 characters in a file name, so the high-byte
                of name_len is always zero.  However, older kernels
                look at both bytes of name_len, and will get confused
                if we try to store something there.  So we can only
                update the file type field if the feature
                EXT2_FEATURE_INCOMPAT_FILETYPE is enabled.
                I want to get this support into the 2.2 kernel, since
                even if it isn't used much (because people will want
                their filesystems to be compatible with 2.0 kernels),
                we will be able to migrate smoothly to using this
                feature by default in the future.