f2fs: avoid BUG_ON when mouting corrupted image having garbage blocks

If the disk has some garbage blocks, F2FS is able to face with BUG_ON when
recovering direct node blocks.
This patch detects the error case and avoids that prior to reaching BUG_ON.

Alexey Khoroshilov addressed the potential security issues as follows.
"An ability to trigger a BUG_ON assert by mounting a crafted image is
usually considered as a local denial of service [1-3]. As far as I
understand, the reason is that some kernel data may become inconsistent
that can lead to further problems.

[1] http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-3353
[2] http://www.openwall.com/lists/oss-security/2011/06/24/4
[3] http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-2928
etc."

Reported-by: Andrey Tsyvarev <tsyvarev@ispras.ru>
Cc: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Signed-off-by: Dede Dindin Qudsy <xtrymind@gmail.com>
f2fs: handle inline data independently in f2fs_bmap

We'd better handle inline data case independently in f2fs_bmap().
It can reduce our handling time in f2fs_bmap().

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Signed-off-by: Dede Dindin Qudsy <xtrymind@gmail.com>
f2fs: clean up long variable names

This patch includes simple clean-ups to reduce unnecessary long variable names.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Signed-off-by: Dede Dindin Qudsy <xtrymind@gmail.com>
f2fs: pass flags field to setxattr functions

This patch passes the "flags" field to the low level setxattr functions
to use XATTR_REPLACE in the following patches.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Signed-off-by: Dede Dindin Qudsy <xtrymind@gmail.com>
f2fs: return errors right after checking them

This patch adds two error conditions early in the setxattr operations.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Signed-off-by: Dede Dindin Qudsy <xtrymind@gmail.com>
f2fs: submit bio at the reclaim path

If f2fs_write_data_page is called through the reclaim path, we should submit
the bio right away.

This patch resolves the following issue that Marc Dietrich reported.
"It took me a while to bisect a problem which causes my ARM (tegra2) netbook to
frequently stall for 5-10 seconds when I enable EXA acceleration (opentegra
experimental ddx)."
And this patch fixes that.

Reported-by: Marc Dietrich <marvin24@gmx.de>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Signed-off-by: Dede Dindin Qudsy <xtrymind@gmail.com>
f2fs: introduce help macro ADDRS_PER_PAGE()

Introduce help macro ADDRS_PER_PAGE() to get the number of address pointers in
direct node or inode.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Signed-off-by: Dede Dindin Qudsy <xtrymind@gmail.com>
f2fs: introduce struct flush_cmd_control to wrap the flush_merge
 fields

Split the flush_merge fields from sm_i, and use the new struct flush_cmd_control
to wrap it, so that we can igonre these fileds if flush_merge is disable, and
it alse can the structs more neat.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Signed-off-by: Dede Dindin Qudsy <xtrymind@gmail.com>
f2fs: introduce help function {create,destroy}_flush_cmd_control

Introduce help function {create,destroy}_flush_cmd_control to clean up
the create/destory flush merge operation.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Signed-off-by: Dede Dindin Qudsy <xtrymind@gmail.com>
f2fs: introduce f2fs_seek_block to support SEEK_{DATA, HOLE} in
 llseek

In This patch we introduce f2fs_seek_block to support SEEK_{DATA,HOLE} of
lseek(2).

change log from v1:
 o fix bug when lseek from middle of page and fix wrong calculation of
PGOFS_OF_NEXT_DNODE macro.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

Signed-off-by: Dede Dindin Qudsy <xtrymind@gmail.com>