Now we avoid throttling swap writes by determining whether the current
process is kswapd (aka current_is_kswapd()), but swap writes can come
from either kswapd or direct reclaim, so the swap writes from direct
reclaim will still be throttled.
When a process holds a lock to allocate a free page, and enters direct
reclaim because there is no free memory, then it might trigger a hung
due to the wbt throttling that causes other processes to fail to get
the lock.
Both kswapd and direct reclaim set the REQ_SWAP flag, so use REQ_SWAP
instead of current_is_kswapd() to avoid throttling swap writes. Also
renamed WBT_KSWAPD to WBT_SWAP and WBT_RWQ_KSWAPD to WBT_RWQ_SWAP.
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240604030522.3686177-1-libaokun@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The kobject for the queue entries is embedded into a struct gendisk.
Pass it to the sysfs methods instead of the request_queue derived from
it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240627111407.476276-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A lof the code to implement the queue sysfs attributes is repetitive.
Add a few macros to generate the common cases.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20240627111407.476276-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
queue_logical_block_size is never called with a 0 queue, and the
logical_block_size field in queue_limits is always initialized for
a live queue.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20240627111407.476276-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
User will configure allowed iops limit in 1s, and calculate_io_allowed()
will calculate allowed iops in the slice by:
limit * HZ / throtl_slice
However, if limit is quite low, the result can be 0, then
allowed IO in the slice is 0, this will cause missing dispatch and
control will be lower than limit.
For example, set iops_limit to 5 with HD disk, and test will found that
iops will be 3.
This is usually not a big deal, because user will unlikely to configure
such low iops limit, however, this is still a problem in the extreme
scene.
Fix the problem by making sure the wait time calculated by
tg_within_iops_limit() should allow at least one IO to be dispatched.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20240618062108.3680835-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Set the bip_vcnt correctly in bio_integrity_init_user and
bio_integrity_copy_user. If the bio gets split at a later point,
this value is required to set the right bip_vcnt in the cloned bio.
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240626100700.3629-3-anuj20.g@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Block device features and flags were refactored from `enum` to `#define`.
This broke Rust binding generation. This patch fixes the binding
generation.
Fixes: fcf865e357 ("block: convert features and flags to __bitwise types")
Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/r/20240628091152.2185241-1-nmi@metaspace.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
QUEUE_FLAG_SAME_FORCE has been set by rnbd-cnt since the initial
merge. There is no good reason for a driver to force exact core
delivery, which is tunable for very specific workloads and not a
driver setting.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240627124926.512662-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
QUEUE_FLAG_SAME_COMP is already set by default.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240627124926.512662-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Setting QUEUE_FLAG_NOMERGES was added in commit d1b01d14b7 ("scsi:
mpt3sas: Set NVMe device queue depth as 128") without any explanation.
Drivers should second guess the block layer merge decisions, so remove
the flag.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240627124926.512662-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Setting QUEUE_FLAG_NOMERGES was added in commit 15dd03811d
("scsi: megaraid_sas: NVME Interface detection and prop settings")
without any explanation. Drivers should second guess the block
layer merge decisions, so remove the flag.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240627124926.512662-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
QUEUE_FLAG_NOMERGES isn't really a driver interface, but a user tunable.
There also isn't any good reason to set it in the loop driver.
The original commit adding it (5b5e20f421 "block: loop: set
QUEUE_FLAG_NOMERGES for request queue of loop") claims that "It doesn't
make sense to enable merge because the I/O submitted to backing file is
handled page by page." which of course isn't true for multi-page bvec
now, and it never has been for direct I/O, for which commit 40326d8a33
("block/loop: allow request merge for directio mode") alredy disabled
the nomerges flag.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240627124926.512662-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
IO logical block size is one fundamental queue limit, and every IO has
to be aligned with logical block size because our bio split can't deal
with unaligned bio.
The check has to be done with queue usage counter grabbed because device
reconfiguration may change logical block size, and we can prevent the
reconfiguration from happening by holding queue usage counter.
logical_block_size stays in the 1st cache line of queue_limits, and this
cache line is always fetched in fast path via bio_may_exceed_limits(),
so IO perf won't be affected by this check.
Cc: Yi Zhang <yi.zhang@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ye Bin <yebin10@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240620030631.3114026-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Sometimes we need to track the processing order of requests with
ioprio set. So the ioprio of request can be useful information.
Example：
block_rq_insert: 8,0 RA 16384 () 6500840 + 32 be,0,6 [binder:815_3]
block_rq_issue: 8,0 RA 16384 () 6500840 + 32 be,0,6 [binder:815_3]
block_rq_complete: 8,0 RA () 6500840 + 32 be,0,6 [0]
Signed-off-by: Dongliang Cui <dongliang.cui@unisoc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20240614074936.113659-1-dongliang.cui@unisoc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the bvec interation into the generate/verify helpers to avoid a bit
of argument passing churn.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240626045950.189758-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Use a single switch to perform read and write specific checks and exit
early for other operations instead of having two checks using different
predicates.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240626045950.189758-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bio_integrity_add_page can add physically contiguous regions of any size,
so don't bother chunking up the kmalloced buffer.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240626045950.189758-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The PI generation helpers already zero the app tag, so relax the zeroing
to non-PI metadata.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240626045950.189758-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Sparse is a bit dumb about bitwise operation on __bitwise types used
in boolean contexts. Add a !! to explicitly propagate to boolean
without a warning.
Fixes: fcf865e357 ("block: convert features and flags to __bitwise types")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Kent Overstreet <kent.overstreet@linux.dev>
Link: https://lore.kernel.org/r/20240628131657.667797-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1. Userspace sends the command "losetup -d" which uses the open() call
to open the device
2. Kernel receives the ioctl command "LOOP_CLR_FD" which calls the
function loop_clr_fd()
3. If LOOP_CLR_FD is the first command received at the time, then the
AUTOCLEAR flag is not set and deletion of the
loop device proceeds ahead and scans the partitions (drop/add
partitions)
if (disk_openers(lo->lo_disk) > 1) {
lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
loop_global_unlock(lo, true);
return 0;
}
4. Before scanning partitions, it will check to see if any partition of
the loop device is currently opened
5. If any partition is opened, then it will return EBUSY:
if (disk->open_partitions)
return -EBUSY;
6. So, after receiving the "LOOP_CLR_FD" command and just before the above
check for open_partitions, if any other command
(like blkid) opens any partition of the loop device, then the partition
scan will not proceed and EBUSY is returned as shown in above code
7. But in "__loop_clr_fd()", this EBUSY error is not propagated
8. We have noticed that this is causing the partitions of the loop to
remain stale even after the loop device is detached resulting in the
IO errors on the partitions
Fix:
Defer the detach of loop device to release function, which is called when
the last close happens, by setting the lo_flags to LO_FLAGS_AUTOCLEAR at
the time of detach i.e in loop_clr_fd() function.
Test case involves the following two scripts:
script1.sh:
while [ 1 ];
do
losetup -P -f /home/opt/looptest/test10.img
blkid /dev/loop0p1
done
script2.sh:
while [ 1 ];
do
losetup -d /dev/loop0
done
Without fix, the following IO errors have been observed:
kernel: __loop_clr_fd: partition scan of loop0 failed (rc=-16)
kernel: I/O error, dev loop0, sector 20971392 op 0x0:(READ) flags 0x80700
phys_seg 1 prio class 0
kernel: I/O error, dev loop0, sector 108868 op 0x0:(READ) flags 0x0
phys_seg 1 prio class 0
kernel: Buffer I/O error on dev loop0p1, logical block 27201, async page
read
Signed-off-by: Gulam Mohamed <gulam.mohamed@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240618164042.343777-1-gulam.mohamed@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It is odd to check the offset amidst a series of assignments. Moving this
check to the beginning of the function makes the code look better.
Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240625115517.1472120-1-linan666@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
dma_pad_mask is a queue_limits by all ways of looking at it, so move it
there and set it through the atomic queue limits APIs.
Add a little helper that takes the alignment and pad into account to
simplify the code that is touched a bit.
Note that there never was any need for the > check in
blk_queue_update_dma_pad, this probably was just copy and paste from
dma_update_dma_alignment.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20240626142637.300624-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that all updates go through blk_validate_limits the default of 511
is set at initialization time. Also remove the unused NULL check as
calling this helper on a NULL queue can't happen (and doesn't make
much sense to start with).
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20240626142637.300624-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Mark blk_apply_bdi_limits non-static and open code disk_update_readahead
in the only caller.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20240626142637.300624-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
"static" never goes on a line of its own.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20240626142637.300624-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
... and let sparse help us catch mismatches or abuses.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20240626142637.300624-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This is a flag for ->flags and not a feature for ->features. And fix the
one place that actually incorrectly cleared it from ->features.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20240626142637.300624-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Check the features flag and the override flag using the
blk_queue_write_cache, helper otherwise we're going to always
report "write through".
Fixes: 1122c0c1cc ("block: move cache control settings out of queue->flags")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20240626142637.300624-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The md driver wants to enforce a number of flags for all devices, even
when not inheriting them from the underlying devices. To make sure these
flags survive the queue_limits_set calls that md uses to update the
queue limits without deriving them form the previous limits add a new
md_init_stacking_limits helper that calls blk_set_stacking_limits and sets
these flags.
Fixes: 1122c0c1cc ("block: move cache control settings out of queue->flags")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20240626142637.300624-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If we allocate a bio that is larger than NVMe maximum request size,
attach integrity metadata to it and send it to the NVMe subsystem, the
integrity metadata will be corrupted.
Splitting the bio works correctly. The function bio_split will clone the
bio, trim the iterator of the first bio and advance the iterator of the
second bio.
However, the function rq_integrity_vec has a bug - it returns the first
vector of the bio's metadata and completely disregards the metadata
iterator that was advanced when the bio was split. Thus, the second bio
uses the same metadata as the first bio and this leads to metadata
corruption.
This commit changes rq_integrity_vec, so that it calls mp_bvec_iter_bvec
instead of returning the first vector. mp_bvec_iter_bvec reads the
iterator and uses it to build a bvec for the current position in the
iterator.
The "queue_max_integrity_segments(rq->q) > 1" check was removed, because
the updated rq_integrity_vec function works correctly with multiple
segments.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/49d1afaa-f934-6ed2-a678-e0d428c63a65@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Take care of the inverse polarity of the BLK_FEAT_ROTATIONAL flag
vs the old nonrot helper.
Fixes: bd4a633b6f ("block: move the nonrot flag to queue_limits")
Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240624173835.76753-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
make allmodconfig && make W=1 C=1 reports:
modpost: missing MODULE_DESCRIPTION() in drivers/block/brd.o
Add the missing invocation of the MODULE_DESCRIPTION() macro.
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Link: https://lore.kernel.org/r/20240602-md-block-brd-v1-1-e71338e131b6@quicinc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For arm32, we get the following build warning:
In file included from /tmp/next/build/include/linux/printk.h:10,
from /tmp/next/build/include/linux/kernel.h:31,
from /tmp/next/build/block/blk-settings.c:5:
/tmp/next/build/block/blk-settings.c: In function 'blk_validate_atomic_write_limits':
/tmp/next/build/include/asm-generic/div64.h:222:35: warning: comparison of distinct pointer types lacks a cast
222 | (void)(((typeof((n)) *)0) == ((uint64_t *)0)); \
| ^~
The divident for do_div() should be 64b, which it is not. Since we want to
check 2x unsigned ints, just use % operator. This allows us to drop the
chunk_sectors variable.
Fixes: 9da3d1e912 ("block: Add core atomic write support")
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/linux-next/b765d200-4e0f-48b1-a962-7dfa1c4aef9c@kernel.dk/T/#mbf067b1edd89c7f9d7dac6e258c516199953a108
Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20240621183016.3092518-1-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There is no need to conditionally define on CONFIG_BLK_DEV_ZONED the
inline helper functions bdev_nr_zones(), bdev_max_open_zones(),
bdev_max_active_zones() and disk_zone_no() as these function will return
the correct valu in all cases (zoned device or not, including when
CONFIG_BLK_DEV_ZONED is not set). Furthermore, disk_nr_zones()
definition can be simplified as disk->nr_zones is always 0 for regular
block devices.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240621031506.759397-4-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There is no need for bdev_nr_zones() to be an exported function
calculating the number of zones of a block device. Instead, given that
all callers use this helper with a fully initialized block device that
has a gendisk, we can redefine this function as an inline helper in
blkdev.h.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240621031506.759397-3-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In null_register_zoned_dev(), there is no need to set disk->nr_zones as
the now uncoditional call to blk_revalidate_disk_zones() will do that.
So remove the assignment using bdev_nr_zones().
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240621031506.759397-2-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add support to set block layer request_queue atomic write limits. The
limits will be derived from either the namespace or controller atomic
parameters.
NVMe atomic-related parameters are grouped into "normal" and "power-fail"
(or PF) class of parameter. For atomic write support, only PF parameters
are of interest. The "normal" parameters are concerned with racing reads
and writes (which also applies to PF). See NVM Command Set Specification
Revision 1.0d section 2.1.4 for reference.
Whether to use per namespace or controller atomic parameters is decided by
NSFEAT bit 1 - see Figure 97: Identify – Identify Namespace Data
Structure, NVM Command Set.
NVMe namespaces may define an atomic boundary, whereby no atomic guarantees
are provided for a write which straddles this per-lba space boundary. The
block layer merging policy is such that no merges may occur in which the
resultant request would straddle such a boundary.
Unlike SCSI, NVMe specifies no granularity or alignment rules, apart from
atomic boundary rule. In addition, again unlike SCSI, there is no
dedicated atomic write command - a write which adheres to the atomic size
limit and boundary is implicitly atomic.
If NSFEAT bit 1 is set, the following parameters are of interest:
- NAWUPF (Namespace Atomic Write Unit Power Fail)
- NABSPF (Namespace Atomic Boundary Size Power Fail)
- NABO (Namespace Atomic Boundary Offset)
and we set request_queue limits as follows:
- atomic_write_unit_max = rounddown_pow_of_two(NAWUPF)
- atomic_write_max_bytes = NAWUPF
- atomic_write_boundary = NABSPF
If in the unlikely scenario that NABO is non-zero, then atomic writes will
not be supported at all as dealing with this adds extra complexity. This
policy may change in future.
In all cases, atomic_write_unit_min is set to the logical block size.
If NSFEAT bit 1 is unset, the following parameter is of interest:
- AWUPF (Atomic Write Unit Power Fail)
and we set request_queue limits as follows:
- atomic_write_unit_max = rounddown_pow_of_two(AWUPF)
- atomic_write_max_bytes = AWUPF
- atomic_write_boundary = 0
A new function, nvme_valid_atomic_write(), is also called from submission
path to verify that a request has been submitted to the driver will
actually be executed atomically. As mentioned, there is no dedicated NVMe
atomic write command (which may error for a command which exceeds the
controller atomic write limits).
Note on NABSPF:
There seems to be some vagueness in the spec as to whether NABSPF applies
for NSFEAT bit 1 being unset. Figure 97 does not explicitly mention NABSPF
and how it is affected by bit 1. However Figure 4 does tell to check Figure
97 for info about per-namespace parameters, which NABSPF is, so it is
implied. However currently nvme_update_disk_info() does check namespace
parameter NABO regardless of this bit.
Signed-off-by: Alan Adamson <alan.adamson@oracle.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
jpg: total rewrite
Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20240620125359.2684798-11-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add initial support for atomic writes.
As is standard method, feed device properties via modules param, those
being:
- atomic_max_size_blks
- atomic_alignment_blks
- atomic_granularity_blks
- atomic_max_size_with_boundary_blks
- atomic_max_boundary_blks
These just match sbc4r22 section 6.6.4 - Block limits VPD page.
We just support ATOMIC WRITE (16).
The major change in the driver is how we lock the device for RW accesses.
Currently the driver uses a per-device lock for accessing device metadata
and "media" data (calls to do_device_access()) atomically for the duration
of the whole read/write command.
This should not suit verifying atomic writes. Reason being that currently
all reads/writes are atomic, so using atomic writes does not prove
anything.
Change device access model to basis that regular writes only atomic on a
per-sector basis, while reads and atomic writes are fully atomic.
As mentioned, since accessing metadata and device media is atomic,
continue to have regular writes involving metadata - like discard or PI -
as atomic. We can improve this later.
Currently we only support model where overlapping going reads or writes
wait for current access to complete before commencing an atomic write.
This is described in 4.29.3.2 section of the SBC. However, we simplify,
things and wait for all accesses to complete (when issuing an atomic
write).
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-10-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Support is divided into two main areas:
- reading VPD pages and setting sdev request_queue limits
- support WRITE ATOMIC (16) command and tracing
The relevant block limits VPD page need to be read to allow the block layer
request_queue atomic write limits to be set. These VPD page limits are
described in sbc4r22 section 6.6.4 - Block limits VPD page.
There are five limits of interest:
- MAXIMUM ATOMIC TRANSFER LENGTH
- ATOMIC ALIGNMENT
- ATOMIC TRANSFER LENGTH GRANULARITY
- MAXIMUM ATOMIC TRANSFER LENGTH WITH BOUNDARY
- MAXIMUM ATOMIC BOUNDARY SIZE
MAXIMUM ATOMIC TRANSFER LENGTH is the maximum length for a WRITE ATOMIC
(16) command. It will not be greater than the device MAXIMUM TRANSFER
LENGTH.
ATOMIC ALIGNMENT and ATOMIC TRANSFER LENGTH GRANULARITY are the minimum
alignment and length values for an atomic write in terms of logical blocks.
Unlike NVMe, SCSI does not specify an LBA space boundary, but does specify
a per-IO boundary granularity. The maximum boundary size is specified in
MAXIMUM ATOMIC BOUNDARY SIZE. When used, this boundary value is set in the
WRITE ATOMIC (16) ATOMIC BOUNDARY field - layout for the WRITE_ATOMIC_16
command can be found in sbc4r22 section 5.48. This boundary value is the
granularity size at which the device may atomically write the data. A value
of zero in WRITE ATOMIC (16) ATOMIC BOUNDARY field means that all data must
be atomically written together.
MAXIMUM ATOMIC TRANSFER LENGTH WITH BOUNDARY is the maximum atomic write
length if a non-zero boundary value is set.
For atomic write support, the WRITE ATOMIC (16) boundary is not of much
interest, as the block layer expects each request submitted to be executed
atomically. However, the SCSI spec does leave itself open to a quirky
scenario where MAXIMUM ATOMIC TRANSFER LENGTH is zero, yet MAXIMUM ATOMIC
TRANSFER LENGTH WITH BOUNDARY and MAXIMUM ATOMIC BOUNDARY SIZE are both
non-zero. This case will be supported.
To set the block layer request_queue atomic write capabilities, sanitize
the VPD page limits and set limits as follows:
- atomic_write_unit_min is derived from granularity and alignment values.
If no granularity value is not set, use physical block size
- atomic_write_unit_max is derived from MAXIMUM ATOMIC TRANSFER LENGTH. In
the scenario where MAXIMUM ATOMIC TRANSFER LENGTH is zero and boundary
limits are non-zero, use MAXIMUM ATOMIC BOUNDARY SIZE for
atomic_write_unit_max. New flag scsi_disk.use_atomic_write_boundary is
set for this scenario.
- atomic_write_boundary_bytes is set to zero always
SCSI also supports a WRITE ATOMIC (32) command, which is for type 2
protection enabled. This is not going to be supported now, so check for
T10_PI_TYPE2_PROTECTION when setting any request_queue limits.
To handle an atomic write request, add support for WRITE ATOMIC (16)
command in handler sd_setup_atomic_cmnd(). Flag use_atomic_write_boundary
is checked here for encoding ATOMIC BOUNDARY field.
Trace info is also added for WRITE_ATOMIC_16 command.
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-9-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Support atomic writes by submitting a single BIO with the REQ_ATOMIC set.
It must be ensured that the atomic write adheres to its rules, like
naturally aligned offset, so call blkdev_dio_invalid() ->
blkdev_atomic_write_valid() [with renaming blkdev_dio_unaligned() to
blkdev_dio_invalid()] for this purpose. The BIO submission path currently
checks for atomic writes which are too large, so no need to check here.
In blkdev_direct_IO(), if the nr_pages exceeds BIO_MAX_VECS, then we cannot
produce a single BIO, so error in this case.
Finally set FMODE_CAN_ATOMIC_WRITE when the bdev can support atomic writes
and the associated file flag is for O_DIRECT.
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-8-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Extend statx system call to return additional info for atomic write support
support if the specified file is a block device.
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Prasad Singamsetty <prasad.singamsetty@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-7-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add atomic write support, as follows:
- add helper functions to get request_queue atomic write limits
- report request_queue atomic write support limits to sysfs and update Doc
- support to safely merge atomic writes
- deal with splitting atomic writes
- misc helper functions
- add a per-request atomic write flag
New request_queue limits are added, as follows:
- atomic_write_hw_max is set by the block driver and is the maximum length
of an atomic write which the device may support. It is not
necessarily a power-of-2.
- atomic_write_max_sectors is derived from atomic_write_hw_max_sectors and
max_hw_sectors. It is always a power-of-2. Atomic writes may be merged,
and atomic_write_max_sectors would be the limit on a merged atomic write
request size. This value is not capped at max_sectors, as the value in
max_sectors can be controlled from userspace, and it would only cause
trouble if userspace could limit atomic_write_unit_max_bytes and the
other atomic write limits.
- atomic_write_hw_unit_{min,max} are set by the block driver and are the
min/max length of an atomic write unit which the device may support. They
both must be a power-of-2. Typically atomic_write_hw_unit_max will hold
the same value as atomic_write_hw_max.
- atomic_write_unit_{min,max} are derived from
atomic_write_hw_unit_{min,max}, max_hw_sectors, and block core limits.
Both min and max values must be a power-of-2.
- atomic_write_hw_boundary is set by the block driver. If non-zero, it
indicates an LBA space boundary at which an atomic write straddles no
longer is atomically executed by the disk. The value must be a
power-of-2. Note that it would be acceptable to enforce a rule that
atomic_write_hw_boundary_sectors is a multiple of
atomic_write_hw_unit_max, but the resultant code would be more
complicated.
All atomic writes limits are by default set 0 to indicate no atomic write
support. Even though it is assumed by Linux that a logical block can always
be atomically written, we ignore this as it is not of particular interest.
Stacked devices are just not supported either for now.
An atomic write must always be submitted to the block driver as part of a
single request. As such, only a single BIO must be submitted to the block
layer for an atomic write. When a single atomic write BIO is submitted, it
cannot be split. As such, atomic_write_unit_{max, min}_bytes are limited
by the maximum guaranteed BIO size which will not be required to be split.
This max size is calculated by request_queue max segments and the number
of bvecs a BIO can fit, BIO_MAX_VECS. Currently we rely on userspace
issuing a write with iovcnt=1 for pwritev2() - as such, we can rely on each
segment containing PAGE_SIZE of data, apart from the first+last, which each
can fit logical block size of data. The first+last will be LBS
length/aligned as we rely on direct IO alignment rules also.
New sysfs files are added to report the following atomic write limits:
- atomic_write_unit_max_bytes - same as atomic_write_unit_max_sectors in
bytes
- atomic_write_unit_min_bytes - same as atomic_write_unit_min_sectors in
bytes
- atomic_write_boundary_bytes - same as atomic_write_hw_boundary_sectors in
bytes
- atomic_write_max_bytes - same as atomic_write_max_sectors in bytes
Atomic writes may only be merged with other atomic writes and only under
the following conditions:
- total resultant request length <= atomic_write_max_bytes
- the merged write does not straddle a boundary
Helper function bdev_can_atomic_write() is added to indicate whether
atomic writes may be issued to a bdev. If a bdev is a partition, the
partition start must be aligned with both atomic_write_unit_min_sectors
and atomic_write_hw_boundary_sectors.
FSes will rely on the block layer to validate that an atomic write BIO
submitted will be of valid size, so add blk_validate_atomic_write_op_size()
for this purpose. Userspace expects an atomic write which is of invalid
size to be rejected with -EINVAL, so add BLK_STS_INVAL for this. Also use
BLK_STS_INVAL for when a BIO needs to be split, as this should mean an
invalid size BIO.
Flag REQ_ATOMIC is used for indicating an atomic write.
Co-developed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-6-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Extend statx system call to return additional info for atomic write support
support for a file.
Helper function generic_fill_statx_atomic_writes() can be used by FSes to
fill in the relevant statx fields. For now atomic_write_segments_max will
always be 1, otherwise some rules would need to be imposed on iovec length
and alignment, which we don't want now.
Signed-off-by: Prasad Singamsetty <prasad.singamsetty@oracle.com>
jpg: relocate bdev support to another patch
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-5-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
An atomic write is a write issued with torn-write protection, meaning
that for a power failure or any other hardware failure, all or none of the
data from the write will be stored, but never a mix of old and new data.
Userspace may add flag RWF_ATOMIC to pwritev2() to indicate that the
write is to be issued with torn-write prevention, according to special
alignment and length rules.
For any syscall interface utilizing struct iocb, add IOCB_ATOMIC for
iocb->ki_flags field to indicate the same.
A call to statx will give the relevant atomic write info for a file:
- atomic_write_unit_min
- atomic_write_unit_max
- atomic_write_segments_max
Both min and max values must be a power-of-2.
Applications can avail of atomic write feature by ensuring that the total
length of a write is a power-of-2 in size and also sized between
atomic_write_unit_min and atomic_write_unit_max, inclusive. Applications
must ensure that the write is at a naturally-aligned offset in the file
wrt the total write length. The value in atomic_write_segments_max
indicates the upper limit for IOV_ITER iovcnt.
Add file mode flag FMODE_CAN_ATOMIC_WRITE, so files which do not have the
flag set will have RWF_ATOMIC rejected and not just ignored.
Add a type argument to kiocb_set_rw_flags() to allows reads which have
RWF_ATOMIC set to be rejected.
Helper function generic_atomic_write_valid() can be used by FSes to verify
compliant writes. There we check for iov_iter type is for ubuf, which
implies iovcnt==1 for pwritev2(), which is an initial restriction for
atomic_write_segments_max. Initially the only user will be bdev file
operations write handler. We will rely on the block BIO submission path to
ensure write sizes are compliant for the bdev, so we don't need to check
atomic writes sizes yet.
Signed-off-by: Prasad Singamsetty <prasad.singamsetty@oracle.com>
jpg: merge into single patch and much rewrite
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-4-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The purpose of the chunk_sectors limit is to ensure that a mergeble request
fits within the boundary of the chunck_sector value.
Such a feature will be useful for other request_queue boundary limits, so
generalize the chunk_sectors merge code.
This idea was proposed by Hannes Reinecke.
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-3-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently blk_queue_get_max_sectors() is passed a enum req_op. In future
the value returned from blk_queue_get_max_sectors() may depend on certain
request flags, so pass a request pointer.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-2-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
