fs: Add destroy_inode callbacks to filesystems ...

Several filesystems rely on the default function which frees
the struct inode * rather than the filesystem specific inode
which the inode is embedded in. This works because the inode
is the first element in the filesystem specific inode. Let's
not depend on this behaviour and for clarity add the destroy_inode
callbacks to all filesystems.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

fs: Drop trivial .lseek() implementaitons in FS drivers ...

There are no FS drivers that do not implement .lseek callback in the
codebase, so there doesn't seem to exist a use-case where lseek()
would return -ENOSYS due to fsdrv->lseek being NULL. At the same time
a large number of FS drivers implement only the most basic "always
succeeds" custom .lseek() hook.

Change the code of lseek() to treat absense of .lseek() to mean that
no special actions needs to be taken by FS driver and seek is always
successful and drop all of the trivial .lseek() implementations.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

fs: Update FILE position in lseek() ...

Instead on relying on driver callbacks to update 'pos' in FILE, do it
as a part of lseek() code. This allows us to drop a bit of repeating
code as well as making lseek() implementation consistent with write()
and read().

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

fs: squashfs: Switch to dentry cache implementation ...

While at it implement symlink support.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

fs: squashfs: fix "no previous prototype for 'squashfs_set_rootarg'" warning ...

The patch fixes this compiler's warning:

  fs/squashfs/squashfs.c:115:6: warning: no previous prototype for 'squashfs_set_rootarg' [-Wmissing-prototypes]
   void squashfs_set_rootarg(struct squashfs_priv *priv, struct fs_device_d *fsdev)
        ^

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

fs: squashfs: don't reference UBI symbols if UBI isn't compiled in ...

There is no point in trying to append a UBI root option, if there is
no UBI support in barebox.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

fs: squashfs: append linux rootarg for ubi volume ...

If squashfs runs from an ubi volume, append appropriate root kernel
options.

Note that ubiblock support is required in the kernel for that.

Signed-off-by: Enrico Jorns <ejo@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Add filetype and detection for squashfs images ...

This adds `filetype_squashfs` to the list of known filetypes and adds a
detection for squashfs files to file_detect_type(). This currently
matches on the `hsqs` start sequence of an image file.

Additionally, the newly introduced filetype is registered as the type of
the squashfs_driver which allows, for example, to mount squashfs without
the need to specify a type parameter.

This changes enable booting a squashfs with the simple `boot` command
pointing to the location (device) that holds the squashfs.

Note that booting with blspec is limited as the current squashfs driver
is not capable of handling symbolic links.

Signed-off-by: Enrico Jorns <ejo@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

fs: add support for SquashFS 4.0 ...

The driver was imported from Linux 4.4.

Current implementation supports only XZ decompressor.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Tested-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>