When writing lprop nodes, do not forget to set @from to 0 when
switching the LEB. This fixes the following bug:

UBIFS error (pid 27768): ubifs_leb_write: writing -15456 bytes at 16:15880, error -22
UBIFS error (pid 27768): do_commit: commit failed, error -22
UBIFS warning (pid 27768): ubifs_ro_mode: switched to read-only mode, error -22
Pid: 27768, comm: freespace Not tainted 2.6.29-rc4-ubifs-2.6 #43
Call Trace:
 [<ffffffffa00c46d6>] ubifs_ro_mode+0x54/0x56 [ubifs]
 [<ffffffffa00cfa16>] do_commit+0x4f5/0x50a [ubifs]
 [<ffffffffa00cfae7>] ubifs_run_commit+0xbc/0xdb [ubifs]
 [<ffffffffa00d42b9>] ubifs_budget_space+0x742/0x9ed [ubifs]
 [<ffffffff812daf45>] ? __mutex_lock_common+0x361/0x3ae
 [<ffffffffa00bc437>] ? ubifs_write_begin+0x18d/0x44c [ubifs]
 [<ffffffffa00bc5cb>] ubifs_write_begin+0x321/0x44c [ubifs]
 [<ffffffff8106222b>] ? trace_hardirqs_on_caller+0x1f/0x14d
 [<ffffffff81097ce2>] generic_file_buffered_write+0x12f/0x2d9
 [<ffffffff8109828d>] __generic_file_aio_write_nolock+0x261/0x295
 [<ffffffff81098aff>] generic_file_aio_write+0x69/0xc5
 [<ffffffffa00bb914>] ubifs_aio_write+0x14c/0x19e [ubifs]
 [<ffffffff810c8f42>] do_sync_write+0xe7/0x12d
 [<ffffffff81055378>] ? autoremove_wake_function+0x0/0x38
 [<ffffffff81149edc>] ? security_file_permission+0x11/0x13
 [<ffffffff810c9827>] vfs_write+0xab/0x105
 [<ffffffff810c9945>] sys_write+0x47/0x6f
 [<ffffffff8100c35b>] system_call_fastpath+0x16/0x1b
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

The debugging function dbg_chk_lpt_sz() was not working
correctly for small min_io_unit size e.g. NOR flash.
Signed-off-by: NAdrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

The function to traverse and dirty the LPT was still not
dirtying all nodes, with the result that the LPT could
run out of space.
Signed-off-by: NAdrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

These are mostly long lines and wrong indentation warning
fixes. But also there are two volatile variables and
checkpatch.pl complains about them:

WARNING: Use of volatile is usually wrong: see Documentation/volatile-considered-harmful.txt
+       volatile int gc_seq;

WARNING: Use of volatile is usually wrong: see Documentation/volatile-considered-harmful.txt
+       volatile int gced_lnum;

Well, we anyway use smp_wmb() for c->gc_seq and c->gced_lnum, so
these 'volatile' modifiers can be just dropped.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

It is useful to know how we got to the checking function when
hunting the bugs.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Do not forget to check whether lpt debugging is enabled before
running the check functions. This commit also makes some spelling
fixes.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Introduce a new data structure which contains all debugging
stuff inside. This is cleaner than having debugging stuff
directly in 'c'.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

The LPT may have gaps in it because initially empty LEBs
are not added by mkfs.ubifs - because it does not know how
many there are.  Then UBIFS allocates empty LEBs in the
reverse order that they are discovered i.e. they are
added to, and removed from, the front of a list.  That
creates a gap in the middle of the LPT.

The function dirtying the LPT tree (for the purpose of
small model garbage collection) assumed that a gap could
only occur at the very end of the LPT and stopped dirtying
prematurely, which in turn resulted in the LPT running
out of space - something that is designed to be impossible.
Signed-off-by: NAdrian Hunter <ext-adrian.hunter@nokia.com>

'is_a_node()' function was reading from a buffer before
checking the buffer length, resulting in an OOPS as
follows:

BUG: unable to handle kernel paging request at f8f74002
IP: [<f8f9783f>] :ubifs:ubifs_unpack_bits+0xca/0x233
*pde = 19e95067 *pte = 00000000
Oops: 0000 [#1] PREEMPT SMP
Modules linked in: ubifs ubi mtdchar bio2mtd mtd brd video output
[last unloaded: mtd]

Pid: 6414, comm: integck Not tainted (2.6.27-rc6ubifs34 #23)
EIP: 0060:[<f8f9783f>] EFLAGS: 00010246 CPU: 0
EIP is at ubifs_unpack_bits+0xca/0x233 [ubifs]
EAX: 00000000 EBX: f6090630 ECX: d9badcfc EDX: 00000000
ESI: 00000004 EDI: f8f74002 EBP: d9badcec ESP: d9badcc0
 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
Process integck (pid: 6414, ti=d9bac000 task=f727dae0 task.ti=d9bac000)
Stack: 00000006 f7306240 00000002 00000000 d9badcfc d9badd00 0000001c 00000000
       f6090630 f6090630 f8f74000 d9badd10 f8fa1cc9 00000000 f8f74002 00000000
       f8f74002 f60fe128 f6090630 f8f74000 d9badd68 f8fa1e46 00000000 0001e000
Call Trace:
 [<f8fa1cc9>] ? is_a_node+0x30/0x90 [ubifs]
 [<f8fa1e46>] ? dbg_check_ltab+0x11d/0x5bd [ubifs]
 [<f8fa388f>] ? ubifs_lpt_start_commit+0x42/0xed3 [ubifs]
 [<c038e76a>] ? mutex_unlock+0x8/0xa
 [<f8f9625d>] ? ubifs_tnc_start_commit+0x1c8/0xedb [ubifs]
 [<f8f8d90b>] ? do_commit+0x187/0x523 [ubifs]
 [<c038e76a>] ? mutex_unlock+0x8/0xa
 [<f8f7ca17>] ? bud_wbuf_callback+0x22/0x28 [ubifs]
 [<f8f8dd1d>] ? ubifs_run_commit+0x76/0xc0 [ubifs]
 [<f8f8032c>] ? ubifs_sync_fs+0xd2/0xe6 [ubifs]
 [<c01a2e97>] ? vfs_quota_sync+0x0/0x17e
 [<c01a5ba6>] ? quota_sync_sb+0x26/0xbb
 [<c01a2e97>] ? vfs_quota_sync+0x0/0x17e
 [<c01a5c5d>] ? sync_dquots+0x22/0x12c
 [<c0173d1b>] ? __fsync_super+0x19/0x68
 [<c0173d75>] ? fsync_super+0xb/0x19
 [<c0174065>] ? generic_shutdown_super+0x22/0xe7
 [<c01a31fc>] ? vfs_quota_off+0x0/0x5fd
 [<f8f7cf4d>] ? ubifs_kill_sb+0x31/0x35 [ubifs]
 [<c01741f9>] ? deactivate_super+0x5e/0x71
 [<c0187610>] ? mntput_no_expire+0x82/0xe4
 [<c0187905>] ? sys_umount+0x4c/0x2f6
 [<c0187bc8>] ? sys_oldumount+0x19/0x1b
 [<c0103b71>] ? sysenter_do_call+0x12/0x25
 =======================
Code: c1 f8 03 8d 04 07 8b 4d e8 89 01 8b 45 e4 89 10 89 d8 89 f1 d3 e8 85 c0
      74 07 29 d6 83 fe 20 75 2a 89 d8 83 c4 20 5b 5e 5f 5d
EIP: [<f8f9783f>] ubifs_unpack_bits+0xca/0x233 [ubifs] SS:ESP 0068:d9badcc0
---[ end trace 1f02572436518c13 ]---
Signed-off-by: NAdrian Hunter <ext-adrian.hunter@nokia.com>

Also add debugging checks for LPT size and separate
out c->check_lpt_free from unrelated bitfields.
Signed-off-by: NAdrian Hunter <ext-adrian.hunter@nokia.com>

This is a new flash file system. See
http://www.linux-mtd.infradead.org/doc/ubifs.htmlSigned-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: NAdrian Hunter <ext-adrian.hunter@nokia.com>