Add the f2fs_remount function call which will be used
during the filesystem remounting. This function
will help us to change the mount options specific to
f2fs.

Also modify the f2fs background_gc mount option, which
will allow the user to dynamically trun on/off the
garbage collection in f2fs based on the background_gc
value. If background_gc=on, Garbage collection will
be turned off & if background_gc=off, Garbage collection
will be truned on.

By default the garbage collection is on in f2fs.

Change Log:
v2: Incorporated the review comments by Gu Zheng.
    Removing the restore part for VFS flags
    Updating comments with proper flag conditions
    Display GC background option as ON/OFF
    Revised conditions to stop GC in case of remount

v1: Initial changes for adding remount_fs callback
support.

Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: NNamjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: NPankaj Kumar <pankaj.km@samsung.com>
Reviewed-by: NGu Zheng <guz.fnst@cn.fujitsu.com>
[Jaegeuk Kim: change /** with /* for the coding style]
Signed-off-by: NJaegeuk Kim <jaegeuk.kim@samsung.com>

 o mkfs.f2fs supports no discard option.
 o fixed volume label size in 512 bytes.
Signed-off-by: NChangman Lee <cm224.lee@samsung.com>
Signed-off-by: NJaegeuk Kim <jaegeuk.kim@samsung.com>

document to reflect the layout generated by mkfs.f2fs .
Signed-off-by: NHuajun Li <huajun.li.lee@gmail.com>
Signed-off-by: NJaegeuk Kim <jaegeuk.kim@samsung.com>

In f2fs_fs.h, one f2fs inode contains 923 data block pointers, while
f2fs documentation says it is 929. Fix this inconsistence.
Signed-off-by: NHuajun Li <huajun.li.lee@gmail.com>

I moved the f2fs-tools.git into kernel.org.
And I added a new mailing list, linux-f2fs-devel@lists.sourceforge.net.
Signed-off-by: NJaegeuk Kim <jaegeuk.kim@samsung.com>

This adds a document describing the mount options, proc entries, usage, and
design of Flash-Friendly File System, namely F2FS.
Signed-off-by: NJaegeuk Kim <jaegeuk.kim@samsung.com>