linux-stable.git/fs/f2fs/extent_cache.c, branch v4.4.2

f2fs: fix to skip shrinking extent nodes

2015-10-22T16:39:35+00:00

In f2fs_shrink_extent_tree we should stop shrink flow if we have already
shrunk enough nodes in extent cache.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: introduce __try_update_largest_extent

2015-10-09T23:20:53+00:00

This patch adds a new helper __try_update_largest_extent for cleanup.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: optimize code of f2fs_update_extent_tree_range

2015-10-09T23:20:52+00:00

Fix 2 potential problems:
1. when largest extent needs to be invalidated, it will be reset in
   __drop_largest_extent, which makes __is_extent_same after always
   return false, and largest extent unchanged. Now we update it properly.

2. when extent is split and the latter part remains in tree, next_en
   should be the latter part instead of next extent of original extent.
   It will cause merge failure if there is in-place update, although
   there is not, I think this fix will still makes codes less ambiguous.

This patch also simplifies codes of invalidating extents, and optimizes the
procedues that split extent into two.
There are a few modifications after last patch:
1. prev_en now is updated properly.
2. more codes and branches are simplified.

Signed-off-by: Fan li 
Signed-off-by: Jaegeuk Kim

f2fs: drop largest extent by range

2015-10-09T23:20:51+00:00

now we update extent by range, fofs may not be on the largest
extent if the new extent overlaps with it. so add a new function
to drop largest extent properly.

Signed-off-by: Fan li 
Signed-off-by: Jaegeuk Kim

f2fs: declare f2fs_update_extent_tree_range as static

2015-10-09T23:20:50+00:00

This function should be static.

Signed-off-by: Jaegeuk Kim

f2fs: fix incorrect searching position when shrinking extent cache

2015-10-09T23:20:50+00:00

When shrinking extent cache, we have two steps in the flow:
1) shrink objects which are unreferenced by inodes;
2) shrink objects from LRU list of extent cache.

In step 1, if we haven't shrunk enough number of objects, we will try
step 2, but before that we didn't update the searching position which
may point to last inode index in global extent tree, result in failing
to shrink objects by traversing the all inodes' extent tree.

In this patch, we reset searching position to beginning of global extent
tree for fixing.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: trace in batches extent info update

2015-10-09T23:20:49+00:00

Rename trace_f2fs_update_extent_tree to trace_f2fs_update_extent_tree_range,
then expand and enable it to trace in batches extent info updates.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: avoid accessing NULL pointer in f2fs_drop_largest_extent

2015-08-28T17:14:26+00:00

If extent cache is disable, we will encounter oops when triggering direct
IO as below:

BUG: unable to handle kernel NULL pointer dereference at 0000000c
IP: [] f2fs_drop_largest_extent+0xe/0x30 [f2fs]
*pdpt = 000000002bb9a001 *pde = 0000000000000000
Oops: 0000 [#1] SMP
Modules linked in: f2fs(O) fuse bnep rfcomm bluetooth nfsd dm_crypt nfs_acl auth_rpcgss oid_registry nfs binfmt_misc fscache lockd
sunrpc grace snd_intel8x0 snd_ac97_codec ac97_bus snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq snd_timer
snd_seq_device snd soundcore joydev psmouse hid_generic i2c_piix4 serio_raw ppdev mac_hid parport_pc lp parport ext4 jbd2 mbcache
usbhid hid e1000
CPU: 3 PID: 3608 Comm: dd Tainted: G           O    4.2.0-rc4 #12
Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
task: ef161600 ti: ebd5e000 task.ti: ebd5e000
EIP: 0060:[] EFLAGS: 00010202 CPU: 3
EIP is at f2fs_drop_largest_extent+0xe/0x30 [f2fs]
EAX: 00000000 EBX: ddebc000 ECX: 00000000 EDX: 00000000
ESI: ebd5fdf8 EDI: 00000000 EBP: ebd5fd58 ESP: ebd5fd58
 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
CR0: 80050033 CR2: 0000000c CR3: 2c24ee40 CR4: 000006f0
Stack:
 ebd5fda4 f0b8c005 00000000 00000001 00000000 f0b8c430 c816cd68 ddebc000
 ddebc088 00001000 00000555 00000555 ffffffff c160bb00 00055501 00000000
 00000000 00000100 00000000 ebd5fe20 f0b8c430 00000046 ef161600 00001000
Call Trace:
 [] __allocate_data_block+0x1a5/0x260 [f2fs]
 [] ? f2fs_direct_IO+0x370/0x440 [f2fs]
 [] ? down_read+0x30/0x50
 [] f2fs_direct_IO+0x370/0x440 [f2fs]
 [] generic_file_direct_write+0xa5/0x260
 [] ? current_fs_time+0x18/0x50
 [] __generic_file_write_iter+0xbb/0x210
 [] ? generic_file_write_iter+0x2f/0x320
 [] generic_file_write_iter+0x15c/0x320
 [] f2fs_file_write_iter+0x39/0x80 [f2fs]
 [] __vfs_write+0xa9/0xe0
 [] vfs_write+0x97/0x180
 [] SyS_write+0x5b/0xd0
 [] sysenter_do_call+0x12/0x12
Code: 10 8b 50 1c 89 53 14 eb ca 8d 74 26 00 85 f6 74 86 eb a6 0f 0b 90 8d b4 26 00 00 00 00 55 89 e5 3e 8d 74 26 00 8b 80 d4 02 00
00 <8b> 48 0c 39 d1 77 0e 03 48 14 39 ca 73 07 c7 40 14 00 00 00 00
EIP: [] f2fs_drop_largest_extent+0xe/0x30 [f2fs] SS:ESP 0068:ebd5fd58
CR2: 000000000000000c
---[ end trace a38c07026a1afffd ]---

This is because when extent cache is disable, extent_tree pointer in struct
f2fs_inode_info should be NULL, but in f2fs_drop_largest_extent we access
this NULL pointer directly without checking state of extent cache, then,
the oops occurs. Let's fix it by checking state of extent cache before
accessing.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: update extent tree in batches

2015-08-26T18:50:35+00:00

This patch introduce a new helper f2fs_update_extent_tree_range which can
do extent mapping update at a specified range.

The main idea is:
1) punch all mapping info in extent node(s) which are at a specified range;
2) try to merge new extent mapping with adjacent node, or failing that,
   insert the mapping into extent tree as a new node.

In order to see the benefit, I add a function for stating time stamping
count as below:

uint64_t rdtsc(void)
{
	uint32_t lo, hi;
	__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
	return (uint64_t)hi << 32 | lo;
}

My test environment is: ubuntu, intel i7-3770, 16G memory, 256g micron ssd.

truncation path:	update extent cache from truncate_data_blocks_range
non-truncataion path:	update extent cache from other paths
total:			all update paths

a) Removing 128MB file which has one extent node mapping whole range of
file:
1. dd if=/dev/zero of=/mnt/f2fs/128M bs=1M count=128
2. sync
3. rm /mnt/f2fs/128M

Before:
		total		count		average
truncation:	7651022		32768		233.49

Patched:
		total		count		average
truncation:	3321		33		100.64

b) fsstress:
fsstress -d /mnt/f2fs -l 5 -n 100 -p 20
Test times:		5 times.

Before:
		total		count		average
truncation:	5812480.6	20911.6		277.95
non-truncation:	7783845.6	13440.8		579.12
total:		13596326.2	34352.4		395.79

Patched:
		total		count		average
truncation:	1281283.0	3041.6		421.25
non-truncation:	7355844.4	13662.8		538.38
total:		8637127.4	16704.4		517.06

1) For the updates in truncation path:
 - we can see updating in batches leads total tsc and update count reducing
   explicitly;
 - besides, for a single batched updating, punching multiple extent nodes
   in a loop, result in executing more operations, so our average tsc
   increase intensively.
2) For the updates in non-truncation path:
 - there is a little improvement, that is because for the scenario that we
   just need to update in the head or tail of extent node, new interface
   optimize to update info in extent node directly, rather than removing
   original extent node for updating and then inserting that updated one
   into cache as new node.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim

f2fs: lookup neighbor extent nodes for merging later

2015-08-22T05:45:18+00:00

In __lookup_extent_tree_ret we will not try to find neighbor nodes if
we find the target node, in this condition, we will lost the chance to
merge the new mapping with exist extent node later.

So our extent cache of inode will be fragmented after overwrite exist
file, we can see the number of extent node increases intensively in
following test case:

dd if=/dev/zero of=/mnt/f2fs/4m bs=4K count=1024

Extent Cache:
  - Hit Count: L1-1:0 L1-2:0 L2:0
  - Hit Ratio: 0% (0 / 3072)
  - Inner Struct Count: tree: 1, node: 1

dd if=/dev/zero of=/mnt/f2fs/4m bs=4K count=1024 conv=notrunc

Extent Cache:
  - Hit Count: L1-1:2048 L1-2:0 L2:0
  - Hit Ratio: 33% (2048 / 6144)
  - Inner Struct Count: tree: 1, node: 961

This patch fixes to lookup neighbors of target node for further
merging.

Signed-off-by: Chao Yu 
Signed-off-by: Jaegeuk Kim