linux.git/fs/ext4/file.c, branch v5.9

Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2020-08-21T18:03:38+00:00

Pull ext4 updates from Ted Ts'o:
 "Improvements to ext4's block allocator performance for very large file
  systems, especially when the file system or files which are highly
  fragmented. There is a new mount option, prefetch_block_bitmaps which
  will pull in the block bitmaps and set up the in-memory buddy bitmaps
  when the file system is initially mounted.

  Beyond that, a lot of bug fixes and cleanups. In particular, a number
  of changes to make ext4 more robust in the face of write errors or
  file system corruptions"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (46 commits)
  ext4: limit the length of per-inode prealloc list
  ext4: reorganize if statement of ext4_mb_release_context()
  ext4: add mb_debug logging when there are lost chunks
  ext4: Fix comment typo "the the".
  jbd2: clean up checksum verification in do_one_pass()
  ext4: change to use fallthrough macro
  ext4: remove unused parameter of ext4_generic_delete_entry function
  mballoc: replace seq_printf with seq_puts
  ext4: optimize the implementation of ext4_mb_good_group()
  ext4: delete invalid comments near ext4_mb_check_limits()
  ext4: fix typos in ext4_mb_regular_allocator() comment
  ext4: fix checking of directory entry validity for inline directories
  fs: prevent BUG_ON in submit_bh_wbc()
  ext4: correctly restore system zone info when remount fails
  ext4: handle add_system_zone() failure in ext4_setup_system_zone()
  ext4: fold ext4_data_block_valid_rcu() into the caller
  ext4: check journal inode extents more carefully
  ext4: don't allow overlapping system zones
  ext4: handle error of ext4_setup_system_zone() on remount
  ext4: delete the invalid BUGON in ext4_mb_load_buddy_gfp()
  ...

ext4: limit the length of per-inode prealloc list

2020-08-19T16:04:36+00:00

In the scenario of writing sparse files, the per-inode prealloc list may
be very long, resulting in high overhead for ext4_mb_use_preallocated().
To circumvent this problem, we limit the maximum length of per-inode
prealloc list to 512 and allow users to modify it.

After patching, we observed that the sys ratio of cpu has dropped, and
the system throughput has increased significantly. We created a process
to write the sparse file, and the running time of the process on the
fixed kernel was significantly reduced, as follows:

Running time on unfixed kernel：
[root@TENCENT64 ~]# time taskset 0x01 ./sparse /data1/sparce.dat
real    0m2.051s
user    0m0.008s
sys     0m2.026s

Running time on fixed kernel：
[root@TENCENT64 ~]# time taskset 0x01 ./sparse /data1/sparce.dat
real    0m0.471s
user    0m0.004s
sys     0m0.395s

Signed-off-by: Chunguang Xu 
Link: https://lore.kernel.org/r/d7a98178-056b-6db5-6bce-4ead23f4a257@gmail.com
Signed-off-by: Theodore Ts'o

ext4: do not block RWF_NOWAIT dio write on unallocated space

2020-08-06T05:05:46+00:00

Since commit 378f32bab371 ("ext4: introduce direct I/O write using iomap
infrastructure") we don't properly bail out of RWF_NOWAIT direct IO
write if underlying blocks are not allocated. Also
ext4_dio_write_checks() does not honor RWF_NOWAIT when re-acquiring
i_rwsem. Fix both issues.

Fixes: 378f32bab371 ("ext4: introduce direct I/O write using iomap infrastructure")
Cc: stable@kernel.org
Reported-by: Filipe Manana 
Signed-off-by: Jan Kara 
Reviewed-by: Ritesh Harjani 
Link: https://lore.kernel.org/r/20200708153516.9507-1-jack@suse.cz
Signed-off-by: Theodore Ts'o

ext4: fix coding style in file.c

2020-08-06T04:11:15+00:00

Fixed a few coding style issues in file.c

Signed-off-by: Dio Putra 
Link: https://lore.kernel.org/r/239fcd8f-d33f-8621-9e82-0416dd3f9c94@gmail.com
Signed-off-by: Theodore Ts'o

iomap: fall back to buffered writes for invalidation failures

2020-08-05T16:24:16+00:00

Failing to invalid the page cache means data in incoherent, which is
a very bad state for the system.  Always fall back to buffered I/O
through the page cache if we can't invalidate mappings.

Signed-off-by: Christoph Hellwig 
Acked-by: Dave Chinner 
Reviewed-by: Goldwyn Rodrigues 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong 
Acked-by: Bob Peterson 
Acked-by: Damien Le Moal 
Reviewed-by: Theodore Ts'o  # for ext4
Reviewed-by: Andreas Gruenbacher  # for gfs2
Reviewed-by: Ritesh Harjani

ext4: don't block for O_DIRECT if IOCB_NOWAIT is set

2020-06-04T03:16:55+00:00

Running with some debug patches to detect illegal blocking triggered the
extend/unaligned condition in ext4. If ext4 needs to extend the file (and
hence go to buffered IO), or if the app is doing unaligned IO, then ext4
asks the iomap code to wait for IO completion. If the caller asked for
no-wait semantics by setting IOCB_NOWAIT, then ext4 should return -EAGAIN
instead.

Signed-off-by: Jens Axboe 

Link: https://lore.kernel.org/r/76152096-2bbb-7682-8fce-4cb498bcd909@kernel.dk
Signed-off-by: Theodore Ts'o

ext4: handle ext4_mark_inode_dirty errors

2020-06-04T03:16:50+00:00

ext4_mark_inode_dirty() can fail for real reasons. Ignoring its return
value may lead ext4 to ignore real failures that would result in
corruption / crashes. Harden ext4_mark_inode_dirty error paths to fail
as soon as possible and return errors to the caller whenever
appropriate.

One of the possible scnearios when this bug could affected is that
while creating a new inode, its directory entry gets added
successfully but while writing the inode itself mark_inode_dirty
returns error which is ignored. This would result in inconsistency
that the directory entry points to a non-existent inode.

Ran gce-xfstests smoke tests and verified that there were no
regressions.

Signed-off-by: Harshad Shirwadkar 
Link: https://lore.kernel.org/r/20200427013438.219117-1-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o

ext4: start to support iopoll method

2020-03-05T20:40:15+00:00

Since commit "b1b4705d54ab ext4: introduce direct I/O read using
iomap infrastructure", we can easily make ext4 support iopoll
method, just use iomap_dio_iopoll().

Reviewed-by: Jan Kara 
Signed-off-by: Xiaoguang Wang 
Link: https://lore.kernel.org/r/20200207120758.2411-1-xiaoguang.wang@linux.alibaba.com
Signed-off-by: Theodore Ts'o

ext4: Optimize ext4 DIO overwrites

2019-12-26T16:57:18+00:00

Currently we start transaction for mapping every extent for writing
using direct IO. This is unnecessary when we know we are overwriting
already allocated blocks and the overhead of starting a transaction can
be significant especially for multithreaded workloads doing small writes.
Use iomap operations that avoid starting a transaction for direct IO
overwrites.

This improves throughput of 4k random writes - fio jobfile:
[global]
rw=randrw
norandommap=1
invalidate=0
bs=4k
numjobs=16
time_based=1
ramp_time=30
runtime=120
group_reporting=1
ioengine=psync
direct=1
size=16G
filename=file1.0.0:file1.0.1:file1.0.2:file1.0.3:file1.0.4:file1.0.5:file1.0.6:file1.0.7:file1.0.8:file1.0.9:file1.0.10:file1.0.11:file1.0.12:file1.0.13:file1.0.14:file1.0.15:file1.0.16:file1.0.17:file1.0.18:file1.0.19:file1.0.20:file1.0.21:file1.0.22:file1.0.23:file1.0.24:file1.0.25:file1.0.26:file1.0.27:file1.0.28:file1.0.29:file1.0.30:file1.0.31
file_service_type=random
nrfiles=32

from 3018MB/s to 4059MB/s in my test VM running test against simulated
pmem device (note that before iomap conversion, this workload was able
to achieve 3708MB/s because old direct IO path avoided transaction start
for overwrites as well). For dax, the win is even larger improving
throughput from 3042MB/s to 4311MB/s.

Reported-by: Dan Williams 
Signed-off-by: Jan Kara 
Link: https://lore.kernel.org/r/20191218174433.19380-1-jack@suse.cz
Signed-off-by: Theodore Ts'o

ext4: Move to shared i_rwsem even without dioread_nolock mount opt

2019-12-23T04:57:27+00:00

We were using shared locking only in case of dioread_nolock mount option in case
of DIO overwrites. This mount condition is not needed anymore with current code,
since:-

1. No race between buffered writes & DIO overwrites. Since buffIO writes takes
exclusive lock & DIO overwrites will take shared locking. Also DIO path will
make sure to flush and wait for any dirty page cache data.

2. No race between buffered reads & DIO overwrites, since there is no block
allocation that is possible with DIO overwrites. So no stale data exposure
should happen. Same is the case between DIO reads & DIO overwrites.

3. Also other paths like truncate is protected, since we wait there for any DIO
in flight to be over.

Reviewed-by: Jan Kara 
Tested-by: Joseph Qi 
Signed-off-by: Ritesh Harjani 
Link: https://lore.kernel.org/r/20191212055557.11151-4-riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o