The prepare_compress_overwrite() gets/locks a page to prepare a read, and calls
f2fs_read_multi_pages() which checks EOF first. If there's any page beyond EOF,
we unlock the page and set cc->rpages[i] = NULL, which we can't put the page
anymore. This makes page leak, so let's fix by putting that page.

Fixes: a949dc5f ("f2fs: compress: fix race condition of overwrite vs truncate")
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

In below path, it will return ENOENT if filesystem is shutdown:

- f2fs_map_blocks
 - f2fs_get_dnode_of_data
  - f2fs_get_node_page
   - __get_node_page
    - read_node_page
     - is_sbi_flag_set(sbi, SBI_IS_SHUTDOWN)
       return -ENOENT
 - force return value from ENOENT to 0

It should be fine for read case, since it indicates a hole condition,
and caller could use .m_next_pgofs to skip the hole and continue the
lookup.

However it may cause confusing for write case, since leaving a hole
there, and said nothing was wrong doesn't help.

There is at least one case from dax_iomap_actor() will complain that,
so fix this in prior to supporting dax in f2fs.

xfstest generic/388 reports below warning:

ubuntu godown: xfstests-induced forced shutdown of /mnt/scratch_f2fs:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 485833 at fs/dax.c:1127 dax_iomap_actor+0x339/0x370
Call Trace:
 iomap_apply+0x1c4/0x7b0
 ? dax_iomap_rw+0x1c0/0x1c0
 dax_iomap_rw+0xad/0x1c0
 ? dax_iomap_rw+0x1c0/0x1c0
 f2fs_file_write_iter+0x5ab/0x970 [f2fs]
 do_iter_readv_writev+0x273/0x2e0
 do_iter_write+0xab/0x1f0
 vfs_iter_write+0x21/0x40
 iter_file_splice_write+0x287/0x540
 do_splice+0x37c/0xa60
 __x64_sys_splice+0x15f/0x3a0
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x44/0xae

ubuntu godown: xfstests-induced forced shutdown of /mnt/scratch_f2fs:
------------[ cut here ]------------
RIP: 0010:dax_iomap_pte_fault.isra.0+0x72e/0x14a0
Call Trace:
 dax_iomap_fault+0x44/0x70
 f2fs_dax_huge_fault+0x155/0x400 [f2fs]
 f2fs_dax_fault+0x18/0x30 [f2fs]
 __do_fault+0x4e/0x120
 do_fault+0x3cf/0x7a0
 __handle_mm_fault+0xa8c/0xf20
 ? find_held_lock+0x39/0xd0
 handle_mm_fault+0x1b6/0x480
 do_user_addr_fault+0x320/0xcd0
 ? rcu_read_lock_sched_held+0x67/0xc0
 exc_page_fault+0x77/0x3f0
 ? asm_exc_page_fault+0x8/0x30
 asm_exc_page_fault+0x1e/0x30

Fixes: 83a3bfdb ("f2fs: indicate shutdown f2fs to allow unmount successfully")
Signed-off-by: NChao Yu <chao@kernel.org>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Whenever we notice some sluggish issues on our machines, we are always
curious about how well all types of I/O in the f2fs filesystem are
handled. But, it's hard to get this kind of real data. First of all,
we need to reproduce the issue while turning on the profiling tool like
blktrace, but the issue doesn't happen again easily. Second, with the
intervention of any tools, the overall timing of the issue will be
slightly changed and it sometimes makes us hard to figure it out.

So, I added the feature printing out IO latency statistics tracepoint
events, which are minimal things to understand filesystem's I/O related
behaviors, into F2FS_IOSTAT kernel config. With "iostat_enable" sysfs
node on, we can get this statistics info in a periodic way and it
would cause the least overhead.

[samples]
 f2fs_ckpt-254:1-507     [003] ....  2842.439683: f2fs_iostat_latency:
dev = (254,11), iotype [peak lat.(ms)/avg lat.(ms)/count],
rd_data [136/1/801], rd_node [136/1/1704], rd_meta [4/2/4],
wr_sync_data [164/16/3331], wr_sync_node [152/3/648],
wr_sync_meta [160/2/4243], wr_async_data [24/13/15],
wr_async_node [0/0/0], wr_async_meta [0/0/0]

 f2fs_ckpt-254:1-507     [002] ....  2845.450514: f2fs_iostat_latency:
dev = (254,11), iotype [peak lat.(ms)/avg lat.(ms)/count],
rd_data [60/3/456], rd_node [60/3/1258], rd_meta [0/0/1],
wr_sync_data [120/12/2285], wr_sync_node [88/5/428],
wr_sync_meta [52/6/2990], wr_async_data [4/1/3],
wr_async_node [0/0/0], wr_async_meta [0/0/0]
Signed-off-by: NDaeho Jeong <daehojeong@google.com>
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Added F2FS_IOSTAT config option to support getting IO statistics through
sysfs and printing out periodic IO statistics tracepoint events and
moved I/O statistics related codes into separate files for better
maintenance.
Signed-off-by: NDaeho Jeong <daehojeong@google.com>
Reviewed-by: NChao Yu <chao@kernel.org>
[Jaegeuk Kim: set default=y]
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch adds f2fs_sanity_check_cluster() to support doing
sanity check on cluster of compressed file, it will be triggered
from below two paths:

- __f2fs_cluster_blocks()
- f2fs_map_blocks(F2FS_GET_BLOCK_FIEMAP)

And it can detect below three kind of cluster insanity status.

C: COMPRESS_ADDR
N: NULL_ADDR or NEW_ADDR
V: valid blkaddr
*: any value

1. [*|C|*|*]
2. [C|*|C|*]
3. [C|N|N|V]
Signed-off-by: NChao Yu <chao@kernel.org>
[Nathan Chancellor: fix missing inline warning]
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch supports to inject fault into f2fs_kmem_cache_alloc().

Usage:
a) echo 32768 > /sys/fs/f2fs/<dev>/inject_type or
b) mount -o fault_type=32768 <dev> <mountpoint>
Signed-off-by: NChao Yu <chao@kernel.org>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Since cluster is basic unit of compression, one cluster is compressed or
not, so we can calculate valid blocks only for first page in cluster,
the other pages just skip.
Signed-off-by: NFengnan Chang <changfengnan@vivo.com>
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Compressed inode may suffer read performance issue due to it can not
use extent cache, so I propose to add this unaligned extent support
to improve it.

Currently, it only works in readonly format f2fs image.

Unaligned extent: in one compressed cluster, physical block number
will be less than logical block number, so we add an extra physical
block length in extent info in order to indicate such extent status.

The idea is if one whole cluster blocks are contiguous physically,
once its mapping info was readed at first time, we will cache an
unaligned (or aligned) extent info entry in extent cache, it expects
that the mapping info will be hitted when rereading cluster.

Merge policy:
- Aligned extents can be merged.
- Aligned extent and unaligned extent can not be merged.
Signed-off-by: NChao Yu <chao@kernel.org>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Turned back the remmaped sector address to the address in the partition,
when ending io, for compress cache to work properly.

Fixes: 6ce19aff ("f2fs: compress: add compress_inode to cache
compressed blocks")
Signed-off-by: NDaeho Jeong <daehojeong@google.com>
Signed-off-by: NYoungjin Gil <youngjin.gil@samsung.com>
Signed-off-by: NHyeong Jun Kim <hj514.kim@samsung.com>
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

When we print out a discontinuous compression chunk, it shows like a
continuous chunk now. To show it more correctly, I've changed the way of
printing fiemap info like below. Plus, eliminated NEW_ADDR(-1) in fiemap
info, since it is not in fiemap user api manual.

Let's assume 16KB compression cluster.

<before>
   Logical          Physical         Length           Flags
0:  0000000000000000 00000002c091f000 0000000000004000 1008
1:  0000000000004000 00000002c0920000 0000000000004000 1008
  ...
9:  0000000000034000 0000000f8c623000 0000000000004000 1008
10: 0000000000038000 000000101a6eb000 0000000000004000 1008

<after>
0:  0000000000000000 00000002c091f000 0000000000004000 1008
1:  0000000000004000 00000002c0920000 0000000000004000 1008
  ...
9:  0000000000034000 0000000f8c623000 0000000000001000 1008
10: 0000000000035000 000000101a6ea000 0000000000003000 1008
11: 0000000000038000 000000101a6eb000 0000000000002000 1008
12: 000000000003a000 00000002c3544000 0000000000002000 1008

Flags
0x1000 => FIEMAP_EXTENT_MERGED
0x0008 => FIEMAP_EXTENT_ENCODED
Signed-off-by: NDaeho Jeong <daehojeong@google.com>
Tested-by: NEric Biggers <ebiggers@google.com>
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

when we overwrite the whole page in cluster, we don't need read original
data before write, because after write_end(), writepages() can help to
load left data in that cluster.
Signed-off-by: NFengnan Chang <changfengnan@vivo.com>
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Acked-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

We can just check f2fs_lfs_mode() directly.  The block_unaligned_IO()
check is redundant because in LFS mode, f2fs doesn't do direct I/O
writes that aren't block-aligned (due to f2fs_force_buffered_io()
returning true in this case, triggering the fallback to buffered I/O).
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Make f2fs_write_failed() take a 'struct inode' directly rather than a
'struct address_space', as this simplifies it slightly.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

SBI_NEED_FSCK is an indicator that fsck.f2fs needs to be triggered, so it
is not fully critical to stop any IO writes. So, let's allow to write data
instead of reporting EIO forever given SBI_NEED_FSCK, but do keep OPU.

Fixes: 95577278 ("f2fs: drop inplace IO if fs status is abnormal")
Cc: <stable@kernel.org> # v5.13+
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Use invalidate_lock instead of f2fs' private i_mmap_sem. The intended
purpose is exactly the same. By this conversion we fix a long standing
race between hole punching and read(2) / readahead(2) paths that can
lead to stale page cache contents.

CC: Jaegeuk Kim <jaegeuk@kernel.org>
CC: Chao Yu <yuchao0@huawei.com>
CC: linux-f2fs-devel@lists.sourceforge.net
Acked-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJan Kara <jack@suse.cz>

We need to guarantee it's initially zero. Otherwise, it'll hurt entire flag
operations.

Fixes: b763f3be ("f2fs: restructure f2fs page.private layout")
Reviewed-by: NChao Yu <chao@kernel.org>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch supports to migrate swapfile in aligned write mode during
swapon in order to keep swapfile being aligned to section as much as
possible, then pinned swapfile will locates fully filled section which
may not affected by GC.

However, for the case that swapfile's size is not aligned to section
size, it will still leave last extent in file's tail as unaligned due
to its size is smaller than section size, like case #2.

case #1
xfs_io -f /mnt/f2fs/file -c "pwrite 0 4M" -c "fsync"

Before swapon:
 EXT: FILE-OFFSET      BLOCK-RANGE      TOTAL FLAGS
   0: [0..3047]:       1123352..1126399  3048 0x1000
   1: [3048..7143]:    237568..241663    4096 0x1000
   2: [7144..8191]:    245760..246807    1048 0x1001
After swapon:
 EXT: FILE-OFFSET      BLOCK-RANGE      TOTAL FLAGS
   0: [0..8191]:       249856..258047    8192 0x1001
Kmsg:
F2FS-fs (zram0): Swapfile (2) is not align to section:
1) creat(), 2) ioctl(F2FS_IOC_SET_PIN_FILE), 3) fallocate(2097152 * n)

case #2
xfs_io -f /mnt/f2fs/file -c "pwrite 0 3M" -c "fsync"

Before swapon:
 EXT: FILE-OFFSET      BLOCK-RANGE      TOTAL FLAGS
   0: [0..3047]:       246808..249855    3048 0x1000
   1: [3048..6143]:    237568..240663    3096 0x1001
After swapon:
 EXT: FILE-OFFSET      BLOCK-RANGE      TOTAL FLAGS
   0: [0..4095]:       258048..262143    4096 0x1000
   1: [4096..6143]:    238616..240663    2048 0x1001
Kmsg:
F2FS-fs (zram0): Swapfile: last extent is not aligned to section
F2FS-fs (zram0): Swapfile (2) is not align to section:
1) creat(), 2) ioctl(F2FS_IOC_SET_PIN_FILE), 3) fallocate(2097152 * n)
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

After commit af4b6b8e ("f2fs: introduce check_swap_activate_fast()"),
we will never run into original logic of check_swap_activate() before
f2fs supports non 4k-sized page, so let's delete those dead codes.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Support to use address space of inner inode to cache compressed block,
in order to improve cache hit ratio of random read.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Update the logging uses that have unnecessary newlines as the f2fs_printk
function and so its f2fs_<level> macro callers already adds one.

This allows searching single line logging entries with an easier grep and
also avoids unnecessary blank lines in the logging.

Miscellanea:

o Coalesce formats
o Align to open parenthesis
Signed-off-by: NJoe Perches <joe@perches.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

The kernel writes to swap files on f2fs directly without the assistance
of the filesystem. This direct write by kernel can be non-sequential
even when the f2fs is in LFS mode. Such non-sequential write conflicts
with the LFS semantics. Especially when f2fs is set up on zoned block
devices, the non-sequential write causes unaligned write command errors.

To avoid the non-sequential writes to swap files, prevent swap file
activation when the filesystem is in LFS mode.

Fixes: 4969c06a ("f2fs: support swap file w/ DIO")
Signed-off-by: NShin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Cc: stable@vger.kernel.org # v5.10+
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Restruct f2fs page private layout for below reasons:

There are some cases that f2fs wants to set a flag in a page to
indicate a specified status of page:
a) page is in transaction list for atomic write
b) page contains dummy data for aligned write
c) page is migrating for GC
d) page contains inline data for inline inode flush
e) page belongs to merkle tree, and is verified for fsverity
f) page is dirty and has filesystem/inode reference count for writeback
g) page is temporary and has decompress io context reference for compression

There are existed places in page structure we can use to store
f2fs private status/data:
- page.flags: PG_checked, PG_private
- page.private

However it was a mess when we using them, which may cause potential
confliction:
		page.private	PG_private	PG_checked	page._refcount (+1 at most)
a)		-1		set				+1
b)		-2		set
c), d), e)					set
f)		0		set				+1
g)		pointer		set

The other problem is page.flags has no free slot, if we can avoid set
zero to page.private and set PG_private flag, then we use non-zero value
to indicate PG_private status, so that we may have chance to reclaim
PG_private slot for other usage. [1]

The other concern is f2fs has bad scalability in aspect of indicating
more page status.

So in this patch, let's restructure f2fs' page.private as below to
solve above issues:

Layout A: lowest bit should be 1
| bit0 = 1 | bit1 | bit2 | ... | bit MAX | private data .... |
 bit 0	PAGE_PRIVATE_NOT_POINTER
 bit 1	PAGE_PRIVATE_ATOMIC_WRITE
 bit 2	PAGE_PRIVATE_DUMMY_WRITE
 bit 3	PAGE_PRIVATE_ONGOING_MIGRATION
 bit 4	PAGE_PRIVATE_INLINE_INODE
 bit 5	PAGE_PRIVATE_REF_RESOURCE
 bit 6-	f2fs private data

Layout B: lowest bit should be 0
 page.private is a wrapped pointer.

After the change:
		page.private	PG_private	PG_checked	page._refcount (+1 at most)
a)		11		set				+1
b)		101		set				+1
c)		1001		set				+1
d)		10001		set				+1
e)						set
f)		100001		set				+1
g)		pointer		set				+1

[1] https://lore.kernel.org/linux-f2fs-devel/20210422154705.GO3596236@casper.infradead.org/T/#u

Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This tries to fix xfstests/generic/495.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

The final solution can be migrating blocks to form a section-aligned file
internally. Meanwhile, let's ask users to do that when preparing the swap
file initially like:
1) create()
2) ioctl(F2FS_IOC_SET_PIN_FILE)
3) fallocate()
Reported-by: Nkernel test robot <oliver.sang@intel.com>
Fixes: 36e4d958 ("f2fs: check if swapfile is section-alligned")
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

In f2fs_destroy_compress_ctx(), after f2fs_destroy_compress_ctx(),
cc.cluster_idx will be cleared w/ NULL_CLUSTER, f2fs_cluster_blocks()
may check wrong cluster metadata, fix it.

Fixes: 4c8ff709 ("f2fs: support data compression")
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch combined the below three clean-up patches.

- modify open brace '{' following function definitions
- ERROR: spaces required around that ':'
- ERROR: spaces required before the open parenthesis '('
- ERROR: spaces prohibited before that ','
- Made suggested modifications from checkpatch in reference to WARNING:
 Missing a blank line after declarations
Signed-off-by: NYi Zhuang <zhuangyi1@huawei.com>
Signed-off-by: NJia Yang <jiayang5@huawei.com>
Signed-off-by: NJack Qiu <jack.qiu@huawei.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

F2FS inode may have different max size,
so change to use per-inode maxbytes.
Signed-off-by: NChengguang Xu <cgxu519@mykernel.net>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

If the swapfile isn't created by pin and fallocate, it can't be
guaranteed section-aligned, so it may be selected by f2fs gc. When
gc_pin_file_threshold is reached, the address of swapfile may change,
but won't be synchronized to swap_extent, so swap will write to wrong
address, which will cause data corruption.
Signed-off-by: NHuang Jianan <huangjianan@oppo.com>
Signed-off-by: NGuo Weichao <guoweichao@oppo.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Because page_no < sis->max guarantees that the while loop break out
normally, the wrong check contidion here doesn't cause a problem.
Signed-off-by: NHuang Jianan <huangjianan@oppo.com>
Signed-off-by: NGuo Weichao <guoweichao@oppo.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Now swapfile in f2fs directly submit IO to blockdev according to
swapfile extents reported by f2fs when swapon, therefore there is
no need to check IS_SWAPFILE when exec filesystem operation.
Signed-off-by: NHuang Jianan <huangjianan@oppo.com>
Signed-off-by: NGuo Weichao <guoweichao@oppo.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Ever since the addition of multipage bio_vecs BIO_MAX_PAGES has been
horribly confusingly misnamed.  Rename it to BIO_MAX_VECS to stop
confusing users of the bio API.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20210311110137.1132391-2-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

It's often inconvenient to use BIO_MAX_PAGES due to min() requiring the
sign to be the same.  Introduce bio_max_segs() and change BIO_MAX_PAGES to
be unsigned to make it easier for the users.
Reviewed-by: NChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We should use !F2FS_IO_ALIGNED() to check and submit_io directly.

Fixes: 8223ecc4 ("f2fs: fix to add missing F2FS_IO_ALIGNED() condition")
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NDehe Gu <gudehe@huawei.com>
Signed-off-by: NGe Qiu <qiuge@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch deprecates f2fs_trace_io, since f2fs uses page->private more broadly,
resulting in more buggy cases.
Acked-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

With the new ->readahead operation, locked pages are added to the page
cache, preventing two threads from racing with each other to read the
same chunk of file, so this is dead code.
Signed-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

F2FS inode may have different max size, e.g. compressed file have
less blkaddr entries in all its direct-node blocks, result in being
with less max filesize. So change to use per-inode maxbytes.
Suggested-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NChengguang Xu <cgxu519@mykernel.net>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

generic/269 reports a hangtask issue, the root cause is ABBA deadlock
described as below:

Thread A			Thread B
- down_write(&sbi->gc_lock) -- A
				- f2fs_write_data_pages
				 - lock all pages in cluster -- B
				 - f2fs_write_multi_pages
				  - f2fs_write_raw_pages
				   - f2fs_write_single_data_page
				    - f2fs_balance_fs
				     - down_write(&sbi->gc_lock) -- A
- f2fs_gc
 - do_garbage_collect
  - ra_data_block
   - pagecache_get_page -- B

To fix this, it needs to avoid calling f2fs_balance_fs() if there is
still cluster pages been locked in context of cluster writeback, so
instead, let's call f2fs_balance_fs() in the end of
f2fs_write_raw_pages() when all cluster pages were unlocked.

Fixes: 4c8ff709 ("f2fs: support data compression")
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Rework the post-read processing logic to be much easier to understand.

At least one bug is fixed by this: if an I/O error occurred when reading
from disk, decryption and verity would be performed on the uninitialized
data, causing misleading messages in the kernel log.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

f2fs does not natively support extents in metadata, 'extent' in f2fs
is used as a virtual concept, so in f2fs_fiemap() interface, it needs
to tag FIEMAP_EXTENT_MERGED flag to indicated the extent status is a
result of merging.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Relocate f2fs_precache_extents() in prior to check_swap_activate(),
then extent cache can be enabled before its use.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>