If a page is cold, NOT atomit written and need_ipu now, there is
a high probability that IPU should be adapted. For IPU, we try to
check extent tree to get the block index first, instead of reading
the dnode page, where may lead to an useless dnode IO, since no need to
update the dnode index for IPU.
Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch adds an ioctl to flush data in faster device to cold area. User can
give device number and number of segments to move. It doesn't move it if there
is only one device.
The parameter looks like:
struct f2fs_flush_device {
u32 dev_num; /* device number to flush */
u32 segments; /* # of segments to flush */
};
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Now we're doing SSR aggressively more than ever before, so once we reach to
the reserved_segment, f2fs_balance_fs will call f2fs_gc, which triggers
checkpoint everytime. We actually must avoid that.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
- has_not_enough_free_secs
node_secs: 0 dent_secs: 0 freed:0 free_segments:103 reserved:104
- f2fs_gc
- get_victim_by_default
alloc_mode 0, gc_mode 1, max_search 2672, offset 4654, ofs_unit 1
- do_garbage_collect
start_segno 3976, end_segno 3977 type 0
- is_alive
nid 22797, blkaddr 2131882, ofs_in_node 0, version 0x8/0x0
- gc_data_segment 766, segno 3976, block 512/426 not alive
So, this patch fixes subtle corrupted case where node version does not match
to summary version which results in infinite loop by gc.
Reported-by: Yunlei He <heyunlei@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In order to give more spatial locality, this patch changes the block allocation
policy which assigns beginning of partition for small and hot data/node blocks.
In order to do this, we set noheap allocation by default and introduce another
mount option, heap, to reset it back.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch fixes missing increased max cost caused by a patch that we increased
cose of data segments in greedy algorithm.
Cc: <stable@vger.kernel.org> # v4.10+
Fixes: b9cd20619 "f2fs: node segment is prior to data segment selected victim"
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
When doing garbage collection, we try to record segment offset which
locates at next one of last victim, using it as the start offset in
next searching.
But in some corner cases, recorded offset may cross the end of main
segment area, it will cause incorrectly searching in dirty_segmap
bitmap. This patch adds modular operation to avoid this issue.
Reported-by: Yunlei He <heyunlei@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
fix such pclint warning:
...
Loss of precision (arg. no. 2) (unsigned long long to unsigned int))
Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
We use has_not_enough_free_secs to check if there are enough free segments,
(free_sections(sbi) + freed) <=
(node_secs + 2 * dent_secs + imeta_secs +
reserved_sections(sbi) + needed);
Under scenario with large number of dirty nodes, these nodes would be flushed
during cp, as a result, right side of the inequality would be decreased, while
left side stays unchanged if these nodes are flushed in SSR way, which means
there are enough free segments after this cp.
For this case, we just do a bggc instead of fggc.
Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Previously kernel message can show that in which function we do the
injection, but unfortunately, most of the caller are the same, for
tracking more information of injection path, it needs to show upper
caller's name. This patch supports that ability.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Since has_not_enough_free_secs(sbi, 0, 0) must be true if has_not_enough_
free_secs(sbi, sec_freed, 0) is true, write_checkpoint is sure to execute in
both conditions.
Signed-off-by: Yunlong Song <yunlong.song@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
As data segment gc may lead dnode dirty, so the greedy cost for data segment
should be valid blocks * 2, that is data segment is prior to node segment.
Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
For foreground gc, greedy algorithm should be adapted, which makes
this formula work well:
(2 * (100 / config.overprovision + 1) + 6)
But currently, we fg_gc have a prior to select bg_gc victim segments to gc
first, these victims are selected by cost-benefit algorithm, we can't guarantee
such segments have the small valid blocks, which may destroy the f2fs rule, on
the worstest case, would consume all the free segments.
This patch fix this by add a filter in check_bg_victims, if segment's has # of
valid blocks over overprovision ratio, skip such segments.
Cc: <stable@vger.kernel.org>
Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch introduces a new flag to indicate inode status of doing atomic
write committing, so that, we can keep atomic write status for inode
during atomic committing, then we can skip GCing pages of atomic write inode,
that avoids random GCed datas being mixed with current transaction, so
isolation of transaction can be kept.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch series contains several performance tuning patches regarding to the
IO submission flow, in addition to supporting new features such as a ZBC-base
drive and multiple devices.
It also includes some major bug fixes such as:
- checkpoint version control
- fdatasync-related roll-forward recovery routine
- memory boundary or null-pointer access in corner cases
- missing error cases
It has various minor clean-up patches as well.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2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=Boum
-----END PGP SIGNATURE-----
Merge tag 'for-f2fs-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
Pull f2fs updates from Jaegeuk Kim:
"This patch series contains several performance tuning patches
regarding to the IO submission flow, in addition to supporting new
features such as a ZBC-base drive and multiple devices.
It also includes some major bug fixes such as:
- checkpoint version control
- fdatasync-related roll-forward recovery routine
- memory boundary or null-pointer access in corner cases
- missing error cases
It has various minor clean-up patches as well"
* tag 'for-f2fs-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (66 commits)
f2fs: fix a missing size change in f2fs_setattr
f2fs: fix to access nullified flush_cmd_control pointer
f2fs: free meta pages if sanity check for ckpt is failed
f2fs: detect wrong layout
f2fs: call sync_fs when f2fs is idle
Revert "f2fs: use percpu_counter for # of dirty pages in inode"
f2fs: return AOP_WRITEPAGE_ACTIVATE for writepage
f2fs: do not activate auto_recovery for fallocated i_size
f2fs: fix to determine start_cp_addr by sbi->cur_cp_pack
f2fs: fix 32-bit build
f2fs: set ->owner for debugfs status file's file_operations
f2fs: fix incorrect free inode count in ->statfs
f2fs: drop duplicate header timer.h
f2fs: fix wrong AUTO_RECOVER condition
f2fs: do not recover i_size if it's valid
f2fs: fix fdatasync
f2fs: fix to account total free nid correctly
f2fs: fix an infinite loop when flush nodes in cp
f2fs: don't wait writeback for datas during checkpoint
f2fs: fix wrong written_valid_blocks counting
...
Pull block layer updates from Jens Axboe:
"This is the main block pull request this series. Contrary to previous
release, I've kept the core and driver changes in the same branch. We
always ended up having dependencies between the two for obvious
reasons, so makes more sense to keep them together. That said, I'll
probably try and keep more topical branches going forward, especially
for cycles that end up being as busy as this one.
The major parts of this pull request is:
- Improved support for O_DIRECT on block devices, with a small
private implementation instead of using the pig that is
fs/direct-io.c. From Christoph.
- Request completion tracking in a scalable fashion. This is utilized
by two components in this pull, the new hybrid polling and the
writeback queue throttling code.
- Improved support for polling with O_DIRECT, adding a hybrid mode
that combines pure polling with an initial sleep. From me.
- Support for automatic throttling of writeback queues on the block
side. This uses feedback from the device completion latencies to
scale the queue on the block side up or down. From me.
- Support from SMR drives in the block layer and for SD. From Hannes
and Shaun.
- Multi-connection support for nbd. From Josef.
- Cleanup of request and bio flags, so we have a clear split between
which are bio (or rq) private, and which ones are shared. From
Christoph.
- A set of patches from Bart, that improve how we handle queue
stopping and starting in blk-mq.
- Support for WRITE_ZEROES from Chaitanya.
- Lightnvm updates from Javier/Matias.
- Supoort for FC for the nvme-over-fabrics code. From James Smart.
- A bunch of fixes from a whole slew of people, too many to name
here"
* 'for-4.10/block' of git://git.kernel.dk/linux-block: (182 commits)
blk-stat: fix a few cases of missing batch flushing
blk-flush: run the queue when inserting blk-mq flush
elevator: make the rqhash helpers exported
blk-mq: abstract out blk_mq_dispatch_rq_list() helper
blk-mq: add blk_mq_start_stopped_hw_queue()
block: improve handling of the magic discard payload
blk-wbt: don't throttle discard or write zeroes
nbd: use dev_err_ratelimited in io path
nbd: reset the setup task for NBD_CLEAR_SOCK
nvme-fabrics: Add FC LLDD loopback driver to test FC-NVME
nvme-fabrics: Add target support for FC transport
nvme-fabrics: Add host support for FC transport
nvme-fabrics: Add FC transport LLDD api definitions
nvme-fabrics: Add FC transport FC-NVME definitions
nvme-fabrics: Add FC transport error codes to nvme.h
Add type 0x28 NVME type code to scsi fc headers
nvme-fabrics: patch target code in prep for FC transport support
nvme-fabrics: set sqe.command_id in core not transports
parser: add u64 number parser
nvme-rdma: align to generic ib_event logging helper
...
Normally, while committing checkpoint, we will wait on all pages to be
writebacked no matter the page is data or metadata, so in scenario where
there are lots of data IO being submitted with metadata, we may suffer
long latency for waiting writeback during checkpoint.
Indeed, we only care about persistence for pages with metadata, but not
pages with data, as file system consistent are only related to metadate,
so in order to avoid encountering long latency in above scenario, let's
recognize and reference metadata in submitted IOs, wait writeback only
for metadatas.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If many threads hit has_not_enough_free_secs() in f2fs_balance_fs() at the same
time, all the threads would do FG_GC or BG_GC.
In this critical path, we totally don't need to do BG_GC at all.
Let's avoid that.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If one block has been to written to a new place, just return
in move data process. This patch check it again with holding
page lock.
Signed-off-by: Yunlei He <heyunlei@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If there is no dirty pages in inode, we should give a chance to detach
the inode from global dirty list, otherwise it needs to call another
unnecessary .writepages for detaching.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Remove the WRITE_* and READ_SYNC wrappers, and just use the flags
directly. Where applicable this also drops usage of the
bio_set_op_attrs wrapper.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
This patch adds to support checkpoint error injection in f2fs for testing
fatal error tolerance, it will be useful that it can simulate abnormal
power off by f2fs itself instead of calling godown ioctl by running apps.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Previously, we only support global fault injection configuration, so that
when we configure type/rate of fault injection through sysfs, mount
option, it will influence all f2fs partition which is being used.
It is not make sence, since it will be not convenient if developer want
to test separated partitions with different fault injection rate/type
simultaneously, also it's not possible to enable fault injection in one
partition and disable fault injection in other one.
>From now on, we move global configuration of fault injection in module
into per-superblock, hence injection testing can be more flexible.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Otherwise, we can hit
f2fs_bug_on(sbi, !PageUptodate(sum_page));
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
We should call put_page for preloaded summary pages in do_garbage_collect.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch adds a return value of write_checkpoint for f2fs_gc.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch changes to check valid block number of one GCed section
directly instead of checking the number in all segments of section
one by one in order to clean up codes of foreground GC.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
replacing redundant inode page updates with mark_inode_dirty calls. And we tried
to reduce lock contentions as well to improve filesystem scalability.
Other feature is setting F2FS automatically when detecting host-managed SMR.
= Enhancement =
- ioctl to move a range of data between files
- inject orphan inode errors
- avoid flush commands congestion
- support lazytime
= Bug fixes =
- return proper results for some dentry operations
- fix deadlock in add_link failure
- disable extent_cache for fcollapse/finsert
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1
iQIcBAABAgAGBQJXmDJFAAoJEEAUqH6CSFDSJeYP/0ru8+5/ui5VTCdNPQB9KxYD
DIUaDGpeoLvmn3ZdrMEdyNr6kWbgjCE9JjOGPQ7l1/apErOGVPyaBwflKcCDwloU
pAlEqVM1Q9j4qH4i9SWTlvPtsHBHB7G7YSe3vDB9fJGSTqumubIlnaBm+Wfjx31U
p53WcPn9LpOyzfmvZf2tOHmvZ7bWLkE/a07x9kPC6XHUFb9C17jLRFFGeuhZQHv1
Yo7HgokBnPExa8TnEILYyX/x+eecFS/1Cp/cN0STsebSu8pStTHTcAP7qEpKQB88
Cc51Lf+d5gFeydxKDFxwdH3VWOGIr9Ppako+lHW83gJcHP0zw8zdxULab+HJMa4n
MOByRRiafwu1sL0dl7TCfsYNIHdEnXhWbhcRhMVZbb5C2Q6+Htuac8ZrKSOWExNN
DUqRkzeTib9u+cHxUTFFPgOGdUjDLmg3XHU7mvb+2hViluVjIImC4tqD5XPpv7vt
WnaDJxLCGD/6DF2yhiVY9NysuxInLTNFFCF06LworZ4L24hlg5TvN0UeUNRO9954
ux6f+lSORCzV3TmrsHP5vwjSAW26FviPXV1q1HHJeTpWKMlhsZtHmOAJOtZKKmxP
WFnHT0aiWF+sQf4qfxVQL+lLqtgRKJAI9zqGRyfDJWJp5aXdRuVsZs9pWNQF7lCo
5gVnCYk3ULjXG3b23j2S
=tKTR
-----END PGP SIGNATURE-----
Merge tag 'for-f2fs-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
Pull f2fs updates from Jaegeuk Kim:
"The major change in this version is mitigating cpu overheads on write
paths by replacing redundant inode page updates with mark_inode_dirty
calls. And we tried to reduce lock contentions as well to improve
filesystem scalability. Other feature is setting F2FS automatically
when detecting host-managed SMR.
Enhancements:
- ioctl to move a range of data between files
- inject orphan inode errors
- avoid flush commands congestion
- support lazytime
Bug fixes:
- return proper results for some dentry operations
- fix deadlock in add_link failure
- disable extent_cache for fcollapse/finsert"
* tag 'for-f2fs-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (68 commits)
f2fs: clean up coding style and redundancy
f2fs: get victim segment again after new cp
f2fs: handle error case with f2fs_bug_on
f2fs: avoid data race when deciding checkpoin in f2fs_sync_file
f2fs: support an ioctl to move a range of data blocks
f2fs: fix to report error number of f2fs_find_entry
f2fs: avoid memory allocation failure due to a long length
f2fs: reset default idle interval value
f2fs: use blk_plug in all the possible paths
f2fs: fix to avoid data update racing between GC and DIO
f2fs: add maximum prefree segments
f2fs: disable extent_cache for fcollapse/finsert inodes
f2fs: refactor __exchange_data_block for speed up
f2fs: fix ERR_PTR returned by bio
f2fs: avoid mark_inode_dirty
f2fs: move i_size_write in f2fs_write_end
f2fs: fix to avoid redundant discard during fstrim
f2fs: avoid mismatching block range for discard
f2fs: fix incorrect f_bfree calculation in ->statfs
f2fs: use percpu_rw_semaphore
...
Previous selected segment may become free after write_checkpoint,
if we do garbage collect on this segment, and then new_curseg happen
to reuse it, it may cause f2fs_bug_on as below.
panic+0x154/0x29c
do_garbage_collect+0x15c/0xaf4
f2fs_gc+0x2dc/0x444
f2fs_balance_fs.part.22+0xcc/0x14c
f2fs_balance_fs+0x28/0x34
f2fs_map_blocks+0x5ec/0x790
f2fs_preallocate_blocks+0xe0/0x100
f2fs_file_write_iter+0x64/0x11c
new_sync_write+0xac/0x11c
vfs_write+0x144/0x1e4
SyS_write+0x60/0xc0
Here, maybe we check sit and ssa type during reset_curseg. So, we check
segment is stale or not, and select a new victim to avoid this.
Signed-off-by: Yunlei He <heyunlei@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
These two are confusing leftover of the old world order, combining
values of the REQ_OP_ and REQ_ namespaces. For callers that don't
special case we mostly just replace bi_rw with bio_data_dir or
op_is_write, except for the few cases where a switch over the REQ_OP_
values makes more sense. Any check for READA is replaced with an
explicit check for REQ_RAHEAD. Also remove the READA alias for
REQ_RAHEAD.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This patch reverts 19a5f5e2ef (f2fs: drop any block plugging),
and adds blk_plug in write paths additionally.
The main reason is that blk_start_plug can be used to wake up from low-power
mode before submitting further bios.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Datas in file can be operated by GC and DIO simultaneously, so we will
face race case as below:
For write case:
Thread A Thread B
- generic_file_direct_write
- invalidate_inode_pages2_range
- f2fs_direct_IO
- do_blockdev_direct_IO
- do_direct_IO
- get_more_blocks
- f2fs_gc
- do_garbage_collect
- gc_data_segment
- move_data_page
- do_write_data_page
migrate data block to new block address
- dio_bio_submit
update user data to old block address
For read case:
Thread A Thread B
- generic_file_direct_write
- invalidate_inode_pages2_range
- f2fs_direct_IO
- do_blockdev_direct_IO
- do_direct_IO
- get_more_blocks
- f2fs_balance_fs
- f2fs_gc
- do_garbage_collect
- gc_data_segment
- move_data_page
- do_write_data_page
migrate data block to new block address
- write_checkpoint
- do_checkpoint
- clear_prefree_segments
- f2fs_issue_discard
discard old block adress
- dio_bio_submit
update user buffer from obsolete block address
In order to fix this, for one file, we should let DIO and GC getting exclusion
against with each other.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If we fail to move data page during foreground GC, we should give another
chance to writeback that page which was set dirty previously by writer.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In procedure of synchonized read, after sending out the read request, reader
will try to lock the page for waiting device to finish the read jobs and
unlock the page, but meanwhile, truncater will race with reader, so after
reader get lock of the page, it should check page's mapping to detect
whether someone has truncated the page in advance, then reader has the
chance to do the retry if truncation was done, otherwise read can be failed
due to previous condition check.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In f2fs, we don't need to keep block plugging for NODE and DATA writes, since
we already merged bios as much as possible.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Separate the op from the rq_flag_bits and have f2fs
set/get the bio using bio_set_op_attrs/bio_op.
Signed-off-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
For foreground GC, we cache node blocks in victim section and set them
dirty, then we call sync_node_pages to flush these node pages, but
meanwhile, those node pages which does not locate in victim section
will be flushed together, so more bandwidth and continuous free space
would be occupied.
So for this condition, it's better to leave those unrelated node page
in cache for further write hit, and let CP or VM to flush them afterward.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch splits the existing sync_node_pages into (f)sync_node_pages.
The fsync_node_pages is used for f2fs_sync_file only.
Acked-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Add a new help f2fs_update_data_blkaddr to clean up redundant codes.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
For now, flow of GCing an encrypted data page:
1) try to grab meta page in meta inode's mapping with index of old block
address of that data page
2) load data of ciphertext into meta page
3) allocate new block address
4) write the meta page into new block address
5) update block address pointer in direct node page.
Other reader/writer will use f2fs_wait_on_encrypted_page_writeback to
check and wait on GCed encrypted data cached in meta page writebacked
in order to avoid inconsistence among data page cache, meta page cache
and data on-disk when updating.
However, we will use new block address updated in step 5) as an index to
lookup meta page in inner bio buffer. That would be wrong, and we will
never find the GCing meta page, since we use the old block address as
index of that page in step 1).
This patch fixes the issue by adjust the order of step 1) and step 3),
and in step 1) grab page with index generated in step 3).
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
With a partition which was formated as multi segments in one section,
we stated incorrectly for count of gc operation.
e.g., for a partition with segs_per_sec = 4
cat /sys/kernel/debug/f2fs/status
GC calls: 208 (BG: 7)
- data segments : 104 (52)
- node segments : 104 (24)
GC called count should be (104 (data segs) + 104 (node segs)) / 4 = 52,
rather than 208. Fix it.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch avoids to remain inefficient victim segment number selected by
a victim.
For example, if all the dirty segments has same valid blocks, we can get
the victim segments descending order due to keeping wrong last segment number.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
There are redundant pointer conversion in following call stack:
- at position a, inode was been converted to f2fs_file_info.
- at position b, f2fs_file_info was been converted to inode again.
- truncate_blocks(inode,..)
- fi = F2FS_I(inode) ---a
- ADDRS_PER_PAGE(node_page, fi)
- addrs_per_inode(fi)
- inode = &fi->vfs_inode ---b
- f2fs_has_inline_xattr(inode)
- fi = F2FS_I(inode)
- is_inode_flag_set(fi,..)
In order to avoid unneeded conversion, alter ADDRS_PER_PAGE and
addrs_per_inode to acept parameter with type of inode pointer.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
variable nsearched in get_victim_by_default() indicates the number of
dirty segments we already checked. There are 2 problems about the way
it updates:
1. When p.ofs_unit is greater than 1, the victim we find consists
of multiple segments, possibly more than 1 dirty segment.
But nsearched always increases by 1.
2. If segments have been found but not been chosen, nsearched won't
increase. So even we have checked all dirty segments, nsearched
may still less than p.max_search.
All these problems could cause unnecessary search after all dirty
segments have already been checked.
Signed-off-by: Fan li <fanofcode.li@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In write_begin, if storage supports stable_page, we don't need to wait for
writeback to update its contents.
This patch introduces to use wait_for_stable_page instead of
wait_on_page_writeback.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If we configure section consist of multiple segments, foreground GC will
do the garbage collection with following approach:
for each segment in victim section
blk_start_plug
for each valid block in segment
write out by OPU method
submit bio cache <---
blk_finish_plug <---
There are two issue:
1) for most of the time, 'submit bio cache' will break the merging in
current bio buffer from writes of next segments, making a smaller bio
submitting.
2) block plug only cover IO submitting in one segment, which reduce
opportunity of merging IOs in plug with multiple segments.
So refactor the code as below structure to strive for biggest
opportunity of merging IOs:
blk_start_plug
for each segment in victim section
for each valid block in segment
write out by OPU method
submit bio cache
blk_finish_plug
Test method:
1. mkfs.f2fs -s 8 /dev/sdX
2. touch 32 files
3. write 2M data into each file
4. punch 1.5M data from offset 0 for each file
5. trigger foreground gc through ioctl
Before patch, there are totoally 40 bios submitted.
f2fs_submit_write_bio: dev = (8,32), WRITE_SYNC, DATA, sector = 65536, size = 122880
f2fs_submit_write_bio: dev = (8,32), WRITE_SYNC, DATA, sector = 65776, size = 122880
f2fs_submit_write_bio: dev = (8,32), WRITE_SYNC, DATA, sector = 66016, size = 122880
f2fs_submit_write_bio: dev = (8,32), WRITE_SYNC, DATA, sector = 66256, size = 122880
f2fs_submit_write_bio: dev = (8,32), WRITE_SYNC, DATA, sector = 66496, size = 32768
----repeat for 8 times
After patch, there are totally 35 bios submitted.
f2fs_submit_write_bio: dev = (8,32), WRITE_SYNC, DATA, sector = 65536, size = 122880
----repeat 34 times
f2fs_submit_write_bio: dev = (8,32), WRITE_SYNC, DATA, sector = 73696, size = 16384
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
The scenario is:
1. create lots of node blocks
2. sync
3. write lots of inline_data
-> got panic due to no free space
In that case, we should flush node blocks when writing inline_data in #3,
and trigger gc as well.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch adds last time that user requested filesystem operations.
This information is used to detect whether system is idle or not later.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Sometimes we keep dumb when IO error occur in lower layer device, so user
will not receive any error return value for some operation, but actually,
the operation did not succeed.
This sould be avoided, so this patch reports such kind of error to user.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Use sbi->blocks_per_seg directly to avoid unnecessary calculation when using
1 << sbi->log_blocks_per_seg.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Once f2fs_gc is done, wait_ms is changed once more.
So, its tracepoint would be located after it.
Reported-by: He YunLei <heyunlei@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
different competitors
Since we use different page cache (normally inode's page cache for R/W
and meta inode's page cache for GC) to cache the same physical block
which is belong to an encrypted inode. Writeback of these two page
cache should be exclusive, but now we didn't handle writeback state
well, so there may be potential racing problem:
a)
kworker: f2fs_gc:
- f2fs_write_data_pages
- f2fs_write_data_page
- do_write_data_page
- write_data_page
- f2fs_submit_page_mbio
(page#1 in inode's page cache was queued
in f2fs bio cache, and be ready to write
to new blkaddr)
- gc_data_segment
- move_encrypted_block
- pagecache_get_page
(page#2 in meta inode's page cache
was cached with the invalid datas
of physical block located in new
blkaddr)
- f2fs_submit_page_mbio
(page#1 was submitted, later, page#2
with invalid data will be submitted)
b)
f2fs_gc:
- gc_data_segment
- move_encrypted_block
- f2fs_submit_page_mbio
(page#1 in meta inode's page cache was
queued in f2fs bio cache, and be ready
to write to new blkaddr)
user thread:
- f2fs_write_begin
- f2fs_submit_page_bio
(we submit the request to block layer
to update page#2 in inode's page cache
with physical block located in new
blkaddr, so here we may read gabbage
data from new blkaddr since GC hasn't
writebacked the page#1 yet)
This patch fixes above potential racing problem for encrypted inode.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Now, we use ra_meta_pages to reads continuous physical blocks as much as
possible to improve performance of following reads. However, ra_meta_pages
uses a synchronous readahead approach by submitting bio with READ, as READ
is with high priority, it can not be used in the case of preloading blocks,
and it's not sure when these RAed pages will be used.
This patch supports asynchronous readahead in ra_meta_pages by tagging bio
with READA flag in order to allow preloading.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
For normal inodes, their pages are allocated with __GFP_FS, which can cause
filesystem calls when reclaiming memory.
This can incur a dead lock condition accordingly.
So, this patch addresses this problem by introducing
f2fs_grab_cache_page(.., bool for_write), which calls
grab_cache_page_write_begin() with AOP_FLAG_NOFS.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch introduces a tracepoint to monitor background gc behaviors.
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch drops in batches gc triggered through ioctl, since user
can easily control the gc by designing the loop around the ->ioctl.
We support synchronous gc by forcing using FG_GC in f2fs_gc, so with
it, user can make sure that in this round all blocks gced were
persistent in the device until ioctl returned.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
When searching victim during gc, if there are no dirty segments in
filesystem, we will still take the time to search the whole dirty segment
map, it's not needed, it's better to skip in this condition.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
When doing gc, we search a victim in dirty map, starting from position of
last victim, we will reset the current searching position until we touch
the end of dirty map, and then search the whole diryt map. So sometimes we
will search the range [victim, last] twice, it's redundant, this patch
avoids this issue.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If we do not call get_victim first, we cannot get a new victim for retrial
path.
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch fixes to maintain the right section count freed in garbage
collecting when triggering a foreground gc.
Besides, when a foreground gc is running on current selected section, once
we fail to gc one segment, it's better to abandon gcing the left segments
in current section, because anyway we will select next victim for
foreground gc, so gc on the left segments in previous section will become
overhead and also cause the long latency for caller.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If FG_GC failed to reclaim one section, let's retry with another section
from the start, since we can get anoterh good candidate.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If node blocks were already moved, we don't need to move them again.
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
We should avoid needless checkpoints when there is no dirty and prefree segment.
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
That encrypted page is used temporarily, so we don't need to mark it accessed.
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This makes the function check_dnode have a return type of bool
due to this particular function only ever returning either one
or zero as its return value and changes the name of the function
to is_alive in order to better explain this function's intended
work of checking if a dnode is still in use by the filesystem.
Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
[Jaegeuk Kim: change the return value check for the renamed function]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch adds encryption support in read and write paths.
Note that, in f2fs, we need to consider cleaning operation.
In cleaning procedure, we must avoid encrypting and decrypting written blocks.
So, this patch implements move_encrypted_block().
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch splits find_data_page as follows.
1. f2fs_gc
- use get_read_data_page() with read only
2. find_in_level
- use find_data_page without locked page
3. truncate_partial_page
- In the case cache_only mode, just drop cached page.
- Ohterwise, use get_lock_data_page() and guarantee to truncate
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch adds f2fs_sb_info and page pointers in f2fs_io_info structure.
With this change, we can reduce a lot of parameters for IO functions.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch is for looking into gc performance of f2fs in detail.
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
[Jaegeuk Kim: fix build errors]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch adds FASTBOOT flag into checkpoint as follows.
- CP_UMOUNT_FLAG is set when system is umounted.
- CP_FASTBOOT_FLAG is set when intermediate checkpoint having node summaries
was done.
So, if you get CP_UMOUNT_FLAG from checkpoint, the system was umounted cleanly.
Instead, if there was sudden-power-off, you can get CP_FASTBOOT_FLAG or nothing.
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Use pointer parameter @wait to pass result in {in,de}create_sleep_time for
cleanup.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
No modification in functionality, just clean codes with f2fs_radix_tree_insert.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
There are two slab cache inode_entry_slab and winode_slab using the same
structure as below:
struct dir_inode_entry {
struct list_head list; /* list head */
struct inode *inode; /* vfs inode pointer */
};
struct inode_entry {
struct list_head list;
struct inode *inode;
};
It's a little waste that the two cache can not share their memory space for each
other.
So in this patch we remove one redundant winode_slab slab cache, then use more
universal name struct inode_entry as remaining data structure name of slab,
finally we reuse the inode_entry_slab to store dirty dir item and gc item for
more effective.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch revists retrial paths in f2fs.
The basic idea is to use cond_resched instead of retrying from the very early
stage.
Suggested-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch tries to fix:
BUG: using smp_processor_id() in preemptible [00000000] code: f2fs_gc-254:0/384
(radix_tree_node_alloc+0x14/0x74) from [<c033d8a0>] (radix_tree_insert+0x110/0x200)
(radix_tree_insert+0x110/0x200) from [<c02e8264>] (gc_data_segment+0x340/0x52c)
(gc_data_segment+0x340/0x52c) from [<c02e8658>] (f2fs_gc+0x208/0x400)
(f2fs_gc+0x208/0x400) from [<c02e8a98>] (gc_thread_func+0x248/0x28c)
(gc_thread_func+0x248/0x28c) from [<c0139944>] (kthread+0xa0/0xac)
(kthread+0xa0/0xac) from [<c0105ef8>] (ret_from_fork+0x14/0x3c)
The reason is that f2fs calls radix_tree_insert under enabled preemption.
So, before calling it, we need to call radix_tree_preload.
Otherwise, we should use _GFP_WAIT for the radix tree, and use mutex or
semaphore to cover the radix tree operations.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If there are many inodes that have data blocks in victim segment,
it takes long time to find a inode in gc_inode list.
Let's use radix_tree to reduce lookup time.
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Little cleanup to distinguish each phase easily
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
[Jaegeuk Kim: modify indentation for code readability]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In f2fs_remount, we will stop gc thread and set need_restart_gc as true when new
option is set without BG_GC, then if any error occurred in the following
procedure, we can restore to start the gc thread.
But after that, We will fail to restore gc thread in start_gc_thread as BG_GC is
not set in new option, so we'd better move this condition judgment out of
start_gc_thread to fix this issue.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If a system wants to reduce the booting time as a top priority, now we can
use a mount option, -o fastboot.
With this option, f2fs conducts a little bit slow write_checkpoint, but
it can avoid the node page reads during the next mount time.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Remove the unneeded argument 'type' from __get_victim, use
NO_CHECK_TYPE directly when calling v_ops->get_victim().
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch add a new data structure to control checkpoint parameters.
Currently, it presents the reason of checkpoint such as is_umount and normal
sync.
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In ->get_victim we get max_search value from dirty_i->nr_dirty without
protection of seglist_lock, after that, nr_dirty can be increased/decreased
before we hold seglist_lock lock.
Then in main loop we attempt to traverse all dirty section one time to find
victim section, but it's not accurate to use max_search as the total loop count,
because we might lose checking several sections or check sections redundantly
for the case of nr_dirty are increased or decreased previously.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Previously f2fs only counts dirty dentry pages, but there is no reason not to
expand the scope.
This patch changes the names on the management of dirty pages and to count
dirty pages in each inode info as well.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In gc_node_segment, if node page gc is run concurrently with node page
writeback, and check_valid_map and get_node_page run after page locked
and before cur_valid_map is updated as below, it is possible for the
page to be written twice unnecessarily.
sync_node_pages
try_lock_page
...
check_valid_map f2fs_write_node_page
...
write_node_page
do_write_page
allocate_data_block
...
refresh_sit_entry /* update cur_valid_map */
...
...
unlock_page
get_node_page
...
set_page_dirty
...
f2fs_put_page
unlock_page
This can be solved via calling check_valid_map after get_node_page again.
Signed-off-by: Huang, Ying <ying.huang@intel.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
As the race condition on the inode cache, following scenario can appear:
[Thread a] [Thread b]
->f2fs_mkdir
->f2fs_add_link
->__f2fs_add_link
->init_inode_metadata failed here
->gc_thread_func
->f2fs_gc
->do_garbage_collect
->gc_data_segment
->f2fs_iget
->iget_locked
->wait_on_inode
->unlock_new_inode
->move_data_page
->make_bad_inode
->iput
When we fail in create/symlink/mkdir/mknod/tmpfile, the new allocated inode
should be set as bad to avoid being accessed by other thread. But in above
scenario, it allows f2fs to access the invalid inode before this inode was set
as bad.
This patch fix the potential problem, and this issue was found by code review.
change log from v1:
o Add condition judgment in gc_data_segment() suggested by Changman Lee.
o use iget_failed to simplify code.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Fix typo and some grammatical errors.
The words "filesystem" and "readahead" are being used without the space treewide.
Signed-off-by: Park Ju Hyung <qkrwngud825@gmail.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch uses for_each_set_bit to simplify some codes in f2fs.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If there are multi segments in one section, we will read those SSA blocks which
have contiguous address one by one in f2fs_gc. It may lost performance, let's
read ahead SSA blocks by merge multi read request.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
If f2fs entered errorneous checkpoint status, it should skip writing meta
pages instead of redirtying the pages out.
Otherwise, it cannot unmount the partition even though f2fs is under read-only
status.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
"boo sync" parameter is never referenced in f2fs_wait_on_page_writeback.
We should remove this parameter.
Signed-off-by: Yuan Zhong <yuan.mark.zhong@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Previously during SSR and GC, the maximum number of retrials to find a victim
segment was hard-coded by MAX_VICTIM_SEARCH, 4096 by default.
This number makes an effect on IO locality, when SSR mode is activated, which
results in performance fluctuation on some low-end devices.
If max_victim_search = 4, the victim will be searched like below.
("D" represents a dirty segment, and "*" indicates a selected victim segment.)
D1 D2 D3 D4 D5 D6 D7 D8 D9
[ * ]
[ * ]
[ * ]
[ ....]
This patch adds a sysfs entry to control the number dynamically through:
/sys/fs/f2fs/$dev/max_victim_search
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
When using the f2fs_io_info in the low level, we still need to merge the
rw and rw_flag, so use the rw to hold all the io flags directly,
and remove the rw_flag field.
ps.It is based on the previous patch:
f2fs: move all the bio initialization into __bio_alloc
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch introduces f2fs_io_info to mitigate the complex parameter list.
struct f2fs_io_info {
enum page_type type; /* contains DATA/NODE/META/META_FLUSH */
int rw; /* contains R/RS/W/WS */
int rw_flag; /* contains REQ_META/REQ_PRIO */
}
1. f2fs_write_data_pages
- DATA
- WRITE_SYNC is set when wbc->WB_SYNC_ALL.
2. sync_node_pages
- NODE
- WRITE_SYNC all the time
3. sync_meta_pages
- META
- WRITE_SYNC all the time
- REQ_META | REQ_PRIO all the time
** f2fs_submit_merged_bio() handles META_FLUSH.
4. ra_nat_pages, ra_sit_pages, ra_sum_pages
- META
- READ_SYNC
Cc: Fan Li <fanofcode.li@samsung.com>
Cc: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Previously f2fs submits most of write requests using WRITE_SYNC, but f2fs_write_data_pages
submits last write requests by sync_mode flags callers pass.
This causes a performance problem since continuous pages with different sync flags
can't be merged in cfq IO scheduler(thanks yu chao for pointing it out), and synchronous
requests often take more time.
This patch makes the following modifies to DATA writebacks:
1. every page will be written back using the sync mode caller pass.
2. only pages with the same sync mode can be merged in one bio request.
These changes are restricted to DATA pages.Other types of writebacks are modified
To remain synchronous.
In my test with tiotest, f2fs sequence write performance is improved by about 7%-10% ,
and this patch has no obvious impact on other performance tests.
Signed-off-by: Fan Li <fanofcode.li@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch adds unlikely() macro into the most of codes.
The basic rule is to add that when:
- checking unusual errors,
- checking page mappings,
- and the other unlikely conditions.
Change log from v1:
- Don't add unlikely for the NULL test and error test: advised by Andi Kleen.
Cc: Chao Yu <chao2.yu@samsung.com>
Cc: Andi Kleen <andi@firstfloor.org>
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch integrates redundant bio operations on read and write IOs.
1. Move bio-related codes to the top of data.c.
2. Replace f2fs_submit_bio with f2fs_submit_merged_bio, which handles read
bios additionally.
3. Introduce __submit_merged_bio to submit the merged bio.
4. Change f2fs_readpage to f2fs_submit_page_bio.
5. Introduce f2fs_submit_page_mbio to integrate previous submit_read_page and
submit_write_page.
Reviewed-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Reviewed-by: Chao Yu <chao2.yu@samsung.com >
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch removes the unnecessary condition checks on:
fs/f2fs/gc.c:667 do_garbage_collect() warn: 'sum_page' isn't an ERR_PTR
fs/f2fs/f2fs.h:795 f2fs_put_page() warn: 'page' isn't an ERR_PTR
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch merges some background jobs into this new function.
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Previously, f2fs postpones reclaiming prefree segments into free segments
as much as possible.
However, if user writes and deletes a bunch of data without any sync or fsync
calls, some flash storages can suffer from garbage collections.
So, this patch adds the reclaiming codes to f2fs_write_node_pages and background
GC thread.
If there are a lot of prefree segments, let's do checkpoint so that f2fs
submits discard commands for the prefree regions to the flash storage.
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Introduce the unfailed version of kmem_cache_alloc named f2fs_kmem_cache_alloc
to hide the retry routine and make the code a bit cleaner.
v2:
Fix the wrong use of 'retry' tag pointed out by Gao feng.
Use more neat code to remove redundant tag suggested by Haicheng Li.
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Since the MAX_VICTIM_SEARCH has been enlarged from 20 to 4096,
the victim searching overhead will be increased much than before,
especially for SSR that searches victim for use quiet often.
This patch intends to reduce the overhead a little bit by:
- make the get_gc_cost a inline routine to reduce function call
overhead
- reduce multiplication and division operations
- reduce unnecessary comparison operation
Signed-off-by: Jin Xu <jinuxstyle@gmail.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch improves the gc efficiency by optimizing the victim
selection policy. With this optimization, the random re-write
performance could increase up to 20%.
For f2fs, when disk is in shortage of free spaces, gc will selects
dirty segments and moves valid blocks around for making more space
available. The gc cost of a segment is determined by the valid blocks
in the segment. The less the valid blocks, the higher the efficiency.
The ideal victim segment is the one that has the most garbage blocks.
Currently, it searches up to 20 dirty segments for a victim segment.
The selected victim is not likely the best victim for gc when there
are much more dirty segments. Why not searching more dirty segments
for a better victim? The cost of searching dirty segments is
negligible in comparison to moving blocks.
In this patch, it enlarges the MAX_VICTIM_SEARCH to 4096 to make
the search more aggressively for a possible better victim. Since
it also applies to victim selection for SSR, it will likely improve
the SSR efficiency as well.
The test case is simple. It creates as many files until the disk full.
The size for each file is 32KB. Then it writes as many as 100000
records of 4KB size to random offsets of random files in sync mode.
The testing was done on a 2GB partition of a SDHC card. Let's see the
test result of f2fs without and with the patch.
---------------------------------------
2GB partition, SDHC
create 52023 files of size 32768 bytes
random re-write 100000 records of 4KB
---------------------------------------
| file creation (s) | rewrite time (s) | gc count | gc garbage blocks |
[no patch] 341 4227 1174 174840
[patched] 324 2958 645 106682
It's obvious that, with the patch, f2fs finishes the test in 20+% less
time than without the patch. And internally it does much less gc with
higher efficiency than before.
Since the performance improvement is related to gc, it might not be so
obvious for other tests that do not trigger gc as often as this one (
This is because f2fs selects dirty segments for SSR use most of the
time when free space is in shortage). The well-known iozone test tool
was not used for benchmarking the patch becuase it seems do not have
a test case that performs random re-write on a full disk.
This patch is the revised version based on the suggestion from
Jaegeuk Kim.
Signed-off-by: Jin Xu <jinuxstyle@gmail.com>
[Jaegeuk Kim: suggested simpler solution]
Reviewed-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch enables the number of direct pointers inside on-disk inode block to
be changed dynamically according to the size of inline xattr space.
The number of direct pointers, ADDRS_PER_INODE, can be changed only if the file
has inline xattr flag.
The number of direct pointers that will be used by inline xattrs is defined as
F2FS_INLINE_XATTR_ADDRS.
Current patch assigns F2FS_INLINE_XATTR_ADDRS to 0 temporarily.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch fixes a deadlock bug that occurs quite often when there are
concurrent write and fsync on a same file.
Following is the simplified call trace when tasks get hung.
fsync thread:
- f2fs_sync_file
...
- f2fs_write_data_pages
...
- update_extent_cache
...
- update_inode
- wait_on_page_writeback
bdi writeback thread
- __writeback_single_inode
- f2fs_write_data_pages
- mutex_lock(sbi->writepages)
The deadlock happens when the fsync thread waits on a inode page that has
been added to the f2fs' cached bio sbi->bio[NODE], and unfortunately,
no one else could be able to submit the cached bio to block layer for
writeback. This is because the fsync thread already hold a sbi->fs_lock and
the sbi->writepages lock, causing the bdi thread being blocked when attempt
to write data pages for the same inode. At the same time, f2fs_gc thread
does not notice the situation and could not help. Even the sync syscall
gets blocked.
To fix it, we could submit the cached bio first before waiting on a inode page
that is being written back.
Signed-off-by: Jin Xu <jinuxstyle@gmail.com>
[Jaegeuk Kim: add more cases to use f2fs_wait_on_page_writeback]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Add sysfs entry gc_idle to control the gc policy. Where
gc_idle = 1 corresponds to selecting a cost benefit approach,
while gc_idle = 2 corresponds to selecting a greedy approach
to garbage collection. The selection is mutually exclusive one
approach will work at any point. If gc_idle = 0, then this
option is disabled.
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Reviewed-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
[Jaegeuk Kim: change the select_gc_type() flow slightly]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Add sysfs entries to control the timing parameters for
f2fs gc thread.
Various Sysfs options introduced are:
gc_min_sleep_time: Min Sleep time for GC in ms
gc_max_sleep_time: Max Sleep time for GC in ms
gc_no_gc_sleep_time: Default Sleep time for GC in ms
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Reviewed-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
[Jaegeuk Kim: fix an umount bug and some minor changes]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch simplifies list operations in find_gc_inode and add_gc_inode.
Just simple code cleanup.
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
[Jaegeuk Kim: add description]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Fix the function get_victim_by_default, where it checks
for the condition that p.min_segno != NULL_SEGNO as
shown:
if (p.min_segno != NULL_SEGNO)
goto got_it;
and if above condition is true then
got_it:
if (p.min_segno != NULL_SEGNO) {
So this condition is being checked twice. Hence move the goto
statement after the if condition so that duplication of condition
check is avoided.
Also this function makes a call to get_max_cost() to compute
the max cost based on the f2fs_sbi_info and victim policy. Since
get_max_cost depends on on three parameters of victim_sel_policy
=> alloc_mode, gc_mode & ofs_unit, once this victim policy is
initialised, these value will not change till the execution
time of get_victim_by_default() & also f2fs_sbi_info structure
parameters will not change.
Hence making calls to get_max_cost() in while loop does not seems to
be a good point. Instead we can call it once in begining and store
the results in local variable, which later can serve our purpose
for comparing the cost with max cost inside the while loop.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
when there is an error from kthread_run, then return proper error
rather than returning -ENOMEM.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Some, counters are needed only for the statistical information
while debugging.
So, those can be controlled using CONFIG_F2FS_STAT_FS,
pushing the usage for few variables under this flag.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
If there is no victim segments selected by background GC, let's wait
a little bit longer time to collect dirty segments.
By default, let's give 5 minutes.
Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Add tracepoints for tracing the garbage collector
threads in f2fs with status of collection & type.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
[Jaegeuk: modify slightly to show information]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
In order to be aware of prefree and free sections during FG_GC, let's start with
write_checkpoint().
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
In the previous version, f2fs uses global locks according to the usage types,
such as directory operations, block allocation, block write, and so on.
Reference the following lock types in f2fs.h.
enum lock_type {
RENAME, /* for renaming operations */
DENTRY_OPS, /* for directory operations */
DATA_WRITE, /* for data write */
DATA_NEW, /* for data allocation */
DATA_TRUNC, /* for data truncate */
NODE_NEW, /* for node allocation */
NODE_TRUNC, /* for node truncate */
NODE_WRITE, /* for node write */
NR_LOCK_TYPE,
};
In that case, we lose the performance under the multi-threading environment,
since every types of operations must be conducted one at a time.
In order to address the problem, let's share the locks globally with a mutex
array regardless of any types.
So, let users grab a mutex and perform their jobs in parallel as much as
possbile.
For this, I propose a new global lock scheme as follows.
0. Data structure
- f2fs_sb_info -> mutex_lock[NR_GLOBAL_LOCKS]
- f2fs_sb_info -> node_write
1. mutex_lock_op(sbi)
- try to get an avaiable lock from the array.
- returns the index of the gottern lock variable.
2. mutex_unlock_op(sbi, index of the lock)
- unlock the given index of the lock.
3. mutex_lock_all(sbi)
- grab all the locks in the array before the checkpoint.
4. mutex_unlock_all(sbi)
- release all the locks in the array after checkpoint.
5. block_operations()
- call mutex_lock_all()
- sync_dirty_dir_inodes()
- grab node_write
- sync_node_pages()
Note that,
the pairs of mutex_lock_op()/mutex_unlock_op() and
mutex_lock_all()/mutex_unlock_all() should be used together.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
In order to do GC more reliably, I'd like to lock the vicitm summary page
until its GC is completed, and also prevent any checkpoint process.
Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
The foreground GCs are triggered under not enough free sections.
So, we should not skip moving valid blocks in the victim segments.
Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch removes a bitmap for victim segments selected by foreground GC, and
modifies the other bitmap for victim segments selected by background GC.
1) foreground GC bitmap
: We don't need to manage this, since we just only one previous victim section
number instead of the whole victim history.
The f2fs uses the victim section number in order not to allocate currently
GC'ed section to current active logs.
2) background GC bitmap
: This bitmap is used to avoid selecting victims repeatedly by background GCs.
In addition, the victims are able to be selected by foreground GCs, since
there is no need to read victim blocks during foreground GCs.
By the fact that the foreground GC reclaims segments in a section unit, it'd
be better to manage this bitmap based on the section granularity.
Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
In the SSR case, the max gc cost should be the number of pages in a segment.
Otherwise, f2fs is able to fail getting dirty segments frequently for SSR.
In get_victim_by_default() previously,
while(1) {
...
cost = get_gc_cost(); <- cost is between 0 ~ 512.
...
if (cost == get_max_cost(sbi, &p)) <- max cost is UINT_MAX due to GC_CB type
continue;
if (nsearched++ >= MAX_VICTIM_SEARCH)
break;
}
So, if there are a number of fully valid segments in series, f2fs cannot skip
those segments by comparing the cost and max cost of each segment.
Note that, the cost is the number of valid blocks at the time of the last
checkpoint.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch makes clearer the ambiguous f2fs_gc flow as follows.
1. Remove intermediate checkpoint condition during f2fs_gc
(i.e., should_do_checkpoint() and GC_BLOCKED)
2. Remove unnecessary return values of f2fs_gc because of #1.
(i.e., GC_NODE, GC_OK, etc)
3. Simplify write_checkpoint() because of #2.
4. Clarify the main f2fs_gc flow.
o monitor how many freed sections during one iteration of do_garbage_collect().
o do GC more without checkpoints if we can't get enough free sections.
o do checkpoint once we've got enough free sections through forground GCs.
5. Adopt thread-logging (Slack-Space-Recycle) scheme more aggressively on data
log types. See. get_ssr_segement()
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
When gc thread creation is failed, mark gc_thread as NULL to avoid
crash while trying to stop invalid thread in stop_gc_thread->kthread_stop.
Instead make it return from:
if (!gc_th)
return;
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Currently GC task is started for each f2fs formatted/mounted device.
But, when we check the task list, using 'ps', there is no distinguishing
factor between the tasks. So, name the task as per the block device just
like the flusher threads.
Also, remove the macro GC_THREAD_NAME and instead use the name: f2fs_gc
to avoid name length truncation, as the command length is 16
-> TASK_COMM_LEN 16 and example name like:
f2fs_gc_task:8:16 -> this exceeds name length
Before Patch for 2 F2FS formatted partitions:
root 28061 0.0 0.0 0 0 ? S 10:31 0:00 [f2fs_gc_task]
root 28087 0.0 0.0 0 0 ? S 10:32 0:00 [f2fs_gc_task]
After Patch:
root 16756 0.0 0.0 0 0 ? S 14:57 0:00 [f2fs_gc-8:18]
root 16765 0.0 0.0 0 0 ? S 14:57 0:00 [f2fs_gc-8:19]
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
1. If f2fs is mounted with background_gc_off option, checking
BG_GC is not redundant.
2. f2fs_balance_fs is checked in f2fs_gc, so this is also redundant.
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
1. Background
Previously, if f2fs tries to move data blocks of an *evicting* inode during the
cleaning process, it stops the process incompletely and then restarts the whole
process, since it needs a locked inode to grab victim data pages in its address
space. In order to get a locked inode, iget_locked() by f2fs_iget() is normally
used, but, it waits if the inode is on freeing.
So, here is a deadlock scenario.
1. f2fs_evict_inode() <- inode "A"
2. f2fs_balance_fs()
3. f2fs_gc()
4. gc_data_segment()
5. f2fs_iget() <- inode "A" too!
If step #1 and #5 treat a same inode "A", step #5 would fall into deadlock since
the inode "A" is on freeing. In order to resolve this, f2fs_iget_nowait() which
skips __wait_on_freeing_inode() was introduced in step #5, and stops f2fs_gc()
to complete f2fs_evict_inode().
1. f2fs_evict_inode() <- inode "A"
2. f2fs_balance_fs()
3. f2fs_gc()
4. gc_data_segment()
5. f2fs_iget_nowait() <- inode "A", then stop f2fs_gc() w/ -ENOENT
2. Problem and Solution
In the above scenario, however, f2fs cannot finish f2fs_evict_inode() only if:
o there are not enough free sections, and
o f2fs_gc() tries to move data blocks of the *evicting* inode repeatedly.
So, the final solution is to use f2fs_iget() and remove f2fs_balance_fs() in
f2fs_evict_inode().
The f2fs_evict_inode() actually truncates all the data and node blocks, which
means that it doesn't produce any dirty node pages accordingly.
So, we don't need to do f2fs_balance_fs() in practical.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
After doing a write_checkpoint from garbage collection path if there is still
need to do more garbage collection, gc_more label is used to jump and start
the process again. And in that process, first step before getting victim is to
check if there are not enough free sections, which is already done before
doing a jump to gc_more. We can avoid the redundant call to check free
sections, by checking the gc_type flag which will remain FG_GC(value 1) under
this condition.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch supports ioctl FIFREEZE and FITHAW to snapshot filesystem.
Before calling f2fs_freeze, all writers would be suspended and sync_fs
would be completed. So no f2fs has to do something.
Just background gc operation should be skipped due to generate dirty
nodes and data until unfreeze.
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
The caller of start_bidx_of_node() should give proper node offsets which
point only direct node blocks. Otherwise, it is a caller's bug.
This patch adds comments to make it clear.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Add __init to functions in init_f2fs_fs for code consistency.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
I'd like to revisit the f2fs_gc flow and rewrite as follows.
1. In practical, the nGC parameter of f2fs_gc is meaningless. So, let's
remove it.
2. Background GC marks victim blocks as dirty one at a time.
3. Foreground GC should do cleaning job until acquiring enough free
sections. Afterwards, it needs to do checkpoint.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This patch also resolves the following warning reported by kbuild test robot.
fs/f2fs/gc.c: In function 'start_bidx_of_node':
fs/f2fs/gc.c:453:21: warning: 'bidx' may be used uninitialized in this function
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
No need to initialize "struct f2fs_gc_kthread *gc_th = NULL",
as gc_th = NULL, will be taken care by the return values of kmalloc().
And fix codes in other places.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
As pointed out by Randy Dunlap, this patch removes all usage of "/**" for comment
blocks. Instead, just use "/*".
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This adds on-demand and background cleaning functions.
- The basic background cleaning policy is trying to do cleaning jobs as much as
possible whenever the system is idle. Once the background cleaning is done,
the cleaner sleeps an amount of time not to interfere with VFS calls. The time
is dynamically adjusted according to the status of whole segments, which is
decreased when the following conditions are satisfied.
. GC is not conducted currently, and
. IO subsystem is idle by checking the number of requets in bdev's request
list, and
. There are enough dirty segments.
Otherwise, the time is increased incrementally until to the maximum time.
Note that, min and max times are 10 secs and 30 secs by default.
- F2FS adopts a default victim selection policy where background cleaning uses
a cost-benefit algorithm, while on-demand cleaning uses a greedy algorithm.
- The method of moving data during the cleaning is slightly different between
background and on-demand cleaning schemes. In the case of background cleaning,
F2FS loads the data, and marks them as dirty. Then, F2FS expects that the data
will be moved by flusher or VM. In the case of on-demand cleaning, F2FS should
move the data right away.
- In order to identify valid blocks in a victim segment, F2FS scans the bitmap
of the segment managed as an SIT entry.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
