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Not using the return value can in the generic case be racy, so it's
in general good practice to check the return value instead.
This also resolved the warning caused on ARM and other architectures:
fs/direct-io.c: In function 'sb_init_dio_done_wq':
fs/direct-io.c:557:2: warning: value computed is not used [-Wunused-value]
Signed-off-by: Olof Johansson <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Russell King <[email protected]>
Cc: H Peter Anvin <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Call generic_write_sync() from the deferred I/O completion handler if
O_DSYNC is set for a write request. Also make sure various callers
don't call generic_write_sync if the direct I/O code returns
-EIOCBQUEUED.
Based on an earlier patch from Jan Kara <[email protected]> with updates from
Jeff Moyer <[email protected]> and Darrick J. Wong <[email protected]>.
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Al Viro <[email protected]>
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Add support to the core direct-io code to defer AIO completions to user
context using a workqueue. This replaces opencoded and less efficient
code in XFS and ext4 (we save a memory allocation for each direct IO)
and will be needed to properly support O_(D)SYNC for AIO.
The communication between the filesystem and the direct I/O code requires
a new buffer head flag, which is a bit ugly but not avoidable until the
direct I/O code stops abusing the buffer_head structure for communicating
with the filesystems.
Currently this creates a per-superblock unbound workqueue for these
completions, which is taken from an earlier patch by Jan Kara. I'm
not really convinced about this use and would prefer a "normal" global
workqueue with a high concurrency limit, but this needs further discussion.
JK: Fixed ext4 part, dynamic allocation of the workqueue.
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Al Viro <[email protected]>
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Pull block core updates from Jens Axboe:
- Major bit is Kents prep work for immutable bio vecs.
- Stable candidate fix for a scheduling-while-atomic in the queue
bypass operation.
- Fix for the hang on exceeded rq->datalen 32-bit unsigned when merging
discard bios.
- Tejuns changes to convert the writeback thread pool to the generic
workqueue mechanism.
- Runtime PM framework, SCSI patches exists on top of these in James'
tree.
- A few random fixes.
* 'for-3.10/core' of git://git.kernel.dk/linux-block: (40 commits)
relay: move remove_buf_file inside relay_close_buf
partitions/efi.c: replace useless kzalloc's by kmalloc's
fs/block_dev.c: fix iov_shorten() criteria in blkdev_aio_read()
block: fix max discard sectors limit
blkcg: fix "scheduling while atomic" in blk_queue_bypass_start
Documentation: cfq-iosched: update documentation help for cfq tunables
writeback: expose the bdi_wq workqueue
writeback: replace custom worker pool implementation with unbound workqueue
writeback: remove unused bdi_pending_list
aoe: Fix unitialized var usage
bio-integrity: Add explicit field for owner of bip_buf
block: Add an explicit bio flag for bios that own their bvec
block: Add bio_alloc_pages()
block: Convert some code to bio_for_each_segment_all()
block: Add bio_for_each_segment_all()
bounce: Refactor __blk_queue_bounce to not use bi_io_vec
raid1: use bio_copy_data()
pktcdvd: Use bio_reset() in disabled code to kill bi_idx usage
pktcdvd: use bio_copy_data()
block: Add bio_copy_data()
...
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Faster kernel compiles by way of fewer unnecessary includes.
[[email protected]: fix fallout]
[[email protected]: fix build]
Signed-off-by: Kent Overstreet <[email protected]>
Cc: Zach Brown <[email protected]>
Cc: Felipe Balbi <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Rusty Russell <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Asai Thambi S P <[email protected]>
Cc: Selvan Mani <[email protected]>
Cc: Sam Bradshaw <[email protected]>
Cc: Jeff Moyer <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Benjamin LaHaise <[email protected]>
Reviewed-by: "Theodore Ts'o" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Currently, dio_send_cur_page() submits bio before current page and cached
sdio->cur_page is added to the bio if sdio->boundary is set. This is
actually wrong because sdio->boundary means the current buffer is the last
one before metadata needs to be read. So we should rather submit the bio
after the current page is added to it.
Signed-off-by: Jan Kara <[email protected]>
Reported-by: Kazuya Mio <[email protected]>
Tested-by: Kazuya Mio <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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When we read/write a file sequentially, we will read/write not only the
data blocks but also the indirect blocks that may not be physically
adjacent to the data blocks. So filesystems set the BH_Boundary flag to
submit the previous I/O before reading/writing an indirect block.
However the generic direct IO code mishandles buffer_boundary(), setting
sdio->boundary before each submit_page_section() call which results in
sending only one page bios as underlying code thinks this page is the last
in the contiguous extent. So fix the problem by setting sdio->boundary
only if the current page is really the last one in the mapped extent.
With this patch and "direct-io: submit bio after boundary buffer is added
to it" I've measured about 10% throughput improvement of direct IO reads
on ext3 with SATA harddrive (from 90 MB/s to 100 MB/s). With ramdisk, the
improvement was about 3-fold (from 350 MB/s to 1.2 GB/s). For other
filesystems (such as ext4), the improvements won't be as visible because
the frequency of BH_Boundary flag being set is much smaller.
Signed-off-by: Jan Kara <[email protected]>
Reported-by: Kazuya Mio <[email protected]>
Tested-by: Kazuya Mio <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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More prep work for immutable bvecs:
A few places in the code were either open coding or using the wrong
version - fix.
After we introduce the bvec iter, it'll no longer be possible to modify
the biovec through bio_for_each_segment_all() - it doesn't increment a
pointer to the current bvec, you pass in a struct bio_vec (not a
pointer) which is updated with what the current biovec would be (taking
into account bi_bvec_done and bi_size).
So because of that it's more worthwhile to be consistent about
bio_for_each_segment()/bio_for_each_segment_all() usage.
Signed-off-by: Kent Overstreet <[email protected]>
CC: Jens Axboe <[email protected]>
CC: NeilBrown <[email protected]>
CC: Alasdair Kergon <[email protected]>
CC: [email protected]
CC: Alexander Viro <[email protected]>
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Running AIO is pinning inode in memory using file reference. Once AIO
is completed using aio_complete(), file reference is put and inode can
be freed from memory. So we have to be sure that calling aio_complete()
is the last thing we do with the inode.
CC: Christoph Hellwig <[email protected]>
CC: Jens Axboe <[email protected]>
CC: Jeff Moyer <[email protected]>
CC: [email protected]
Acked-by: Jeff Moyer <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Al Viro <[email protected]>
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Since directio can work on a raw block device, and the block size of the
device can change under it, we need to do the same thing that
fs/buffer.c now does: read the block size a single time, using
ACCESS_ONCE().
Reading it multiple times can get different results, which will then
confuse the code because it actually encodes the i_blksize in
relationship to the underlying logical blocksize.
Signed-off-by: Linus Torvalds <[email protected]>
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Move unplugging for direct I/O from around ->direct_IO() down to
do_blockdev_direct_IO(). This implicitly adds plugging for direct
writes.
CC: Li Shaohua <[email protected]>
Acked-by: Jeff Moyer <[email protected]>
Signed-off-by: Wu Fengguang <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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READ is 0, so the result of the bit-and operation is 0. Rewrite with == as
done elsewhere in the same file.
This problem was found using Coccinelle (http://coccinelle.lip6.fr/).
Signed-off-by: Julia Lawall <[email protected]>
Reviewed-by: Jeff Moyer <[email protected]>
Cc: Al Viro <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Al Viro <[email protected]>
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Use the same mechanism as the block devices are using, but move the
helper functions from fs/direct-io.c into fs/inode.c to remove the
dependency on CONFIG_BLOCK.
Signed-off-by: Trond Myklebust <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Fred Isaman <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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With kernel 3.1, Christoph removed i_alloc_sem and replaced it with
calls (namely inode_dio_wait() and inode_dio_done()) which are
EXPORT_SYMBOL_GPL() thus they cannot be used by non-GPL file systems and
further inode_dio_wait() was pushed from notify_change() into the file
system ->setattr() method but no non-GPL file system can make this call.
That means non-GPL file systems cannot exist any more unless they do not
use any VFS functionality related to reading/writing as far as I can
tell or at least as long as they want to implement direct i/o.
Both Linus and Al (and others) have said on LKML that this breakage of
the VFS API should not have happened and that the change was simply
missed as it was not documented in the change logs of the patches that
did those changes.
This patch changes the two function exports in question to be
EXPORT_SYMBOL() thus restoring the VFS API as it used to be - accessible
for all modules.
Christoph, who introduced the two functions and exported them GPL-only
is CC-ed on this patch to give him the opportunity to object to the
symbols being changed in this manner if he did indeed intend them to be
GPL-only and does not want them to become available to all modules.
Signed-off-by: Anton Altaparmakov <[email protected]>
CC: Christoph Hellwig <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Some investigation of a transaction processing workload showed that a
major consumer of cycles in __blockdev_direct_IO is the cache miss while
accessing the block size. This is because it has to walk the chain from
block_dev to gendisk to queue.
The block size is needed early on to check alignment and sizes. It's only
done if the check for the inode block size fails. But the costly block
device state is unconditionally fetched.
- Reorganize the code to only fetch block dev state when actually
needed.
Then do a prefetch on the block dev early on in the direct IO path. This
is worth it, because there is substantial code run before we actually
touch the block dev now.
- I also added some unlikelies to make it clear the compiler that block
device fetch code is not normally executed.
This gave a small, but measurable improvement on a large database
benchmark (about 0.3%)
[[email protected]: coding-style fixes]
[[email protected]: using prefetch requires including prefetch.h]
Signed-off-by: Andi Kleen <[email protected]>
Cc: Jeff Moyer <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Signed-off-by: Stephen Rothwell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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In get_more_blocks(), we use dio_count to calcuate fs_count and do some
tricky things to increase fs_count if dio_count isn't aligned. But
actually it still has some corner cases that can't be coverd. See the
following example:
dio_write foo -s 1024 -w 4096
(direct write 4096 bytes at offset 1024). The same goes if the offset
isn't aligned to fs_blocksize.
In this case, the old calculation counts fs_count to be 1, but actually we
will write into 2 different blocks (if fs_blocksize=4096). The old code
just works, since it will call get_block twice (and may have to allocate
and create extents twice for filesystems like ext4). So we'd better call
get_block just once with the proper fs_count.
Signed-off-by: Tao Ma <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Al Viro <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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This doesn't change anything for the compiler, but hch thought it would
make the code clearer.
I moved the reference counting into its own little inline.
Signed-off-by: Andi Kleen <[email protected]>
Acked-by: Jeff Moyer <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
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Add inlines to all the submission path functions. While this increases
code size it also gives gcc a lot of optimization opportunities
in this critical hotpath.
In particular -- together with some other changes -- this
allows gcc to get rid of the unnecessary clearing of
sdio at the beginning and optimize the messy parameter passing.
Any non inlining of a function which takes a sdio parameter
would break this optimization because they cannot be done if the
address of a structure is taken.
Note that benefits are only seen with CONFIG_OPTIMIZE_INLINING
and CONFIG_CC_OPTIMIZE_FOR_SIZE both set to off.
This gives about 2.2% improvement on a large database benchmark
with a high IOPS rate.
Signed-off-by: Andi Kleen <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
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Only a single b_private field in the map_bh buffer head is needed after
the submission path. Move map_bh separately to avoid storing
this information in the long term slab.
This avoids the weird 104 byte hole in struct dio_submit which also needed
to be memseted early.
Signed-off-by: Andi Kleen <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
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A direct slab call is slightly faster than kmalloc and can be better cached
per CPU. It also avoids rounding to the next kmalloc slab.
In addition this enforces cache line alignment for struct dio to avoid
any false sharing.
Signed-off-by: Andi Kleen <[email protected]>
Acked-by: Jeff Moyer <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
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Fix most problems reported by pahole.
There is still a weird 104 byte hole after map_bh. I'm not sure what
causes this.
Signed-off-by: Andi Kleen <[email protected]>
Acked-by: Jeff Moyer <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
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There's nothing on the stack, even before my changes.
Signed-off-by: Andi Kleen <[email protected]>
Acked-by: Jeff Moyer <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
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This large, but largely mechanic, patch moves all fields in struct dio
that are only used in the submission path into a separate on stack
data structure. This has the advantage that the memory is very likely
cache hot, which is not guaranteed for memory fresh out of kmalloc.
This also gives gcc more optimization potential because it can easier
determine that there are no external aliases for these variables.
The sdio initialization is a initialization now instead of memset.
This allows gcc to break sdio into individual fields and optimize
away unnecessary zeroing (after all the functions are inlined)
Signed-off-by: Andi Kleen <[email protected]>
Acked-by: Jeff Moyer <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
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This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: Arun Sharma <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: David Miller <[email protected]>
Cc: Eric Dumazet <[email protected]>
Acked-by: Mike Frysinger <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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For filesystems that delay their end_io processing we should keep our
i_dio_count until the the processing is done. Enable this by moving
the inode_dio_done call to the end_io handler if one exist. Note that
the actual move to the workqueue for ext4 and XFS is not done in
this patch yet, but left to the filesystem maintainers. At least
for XFS it's not needed yet either as XFS has an internal equivalent
to i_dio_count.
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Al Viro <[email protected]>
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Maintain i_dio_count for all filesystems, not just those using DIO_LOCKING.
This these filesystems to also protect truncate against direct I/O requests
by using common code. Right now the only non-DIO_LOCKING filesystem that
appears to do so is XFS, which uses an opencoded variant of the i_dio_count
scheme.
Behaviour doesn't change for filesystems never calling inode_dio_wait.
For ext4 behaviour changes when using the dioread_nonlock option, which
previously was missing any protection between truncate and direct I/O reads.
For ocfs2 that handcrafted i_dio_count manipulations are replaced with
the common code now enable.
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Al Viro <[email protected]>
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i_alloc_sem is a rather special rw_semaphore. It's the last one that may
be released by a non-owner, and it's write side is always mirrored by
real exclusion. It's intended use it to wait for all pending direct I/O
requests to finish before starting a truncate.
Replace it with a hand-grown construct:
- exclusion for truncates is already guaranteed by i_mutex, so it can
simply fall way
- the reader side is replaced by an i_dio_count member in struct inode
that counts the number of pending direct I/O requests. Truncate can't
proceed as long as it's non-zero
- when i_dio_count reaches non-zero we wake up a pending truncate using
wake_up_bit on a new bit in i_flags
- new references to i_dio_count can't appear while we are waiting for
it to read zero because the direct I/O count always needs i_mutex
(or an equivalent like XFS's i_iolock) for starting a new operation.
This scheme is much simpler, and saves the space of a spinlock_t and a
struct list_head in struct inode (typically 160 bits on a non-debug 64-bit
system).
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Al Viro <[email protected]>
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Reject zero sized reads as soon as we know our I/O length, and don't
borther with locks or allocations that might have to be cleaned up
otherwise.
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Al Viro <[email protected]>
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* 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block: (65 commits)
Documentation/iostats.txt: bit-size reference etc.
cfq-iosched: removing unnecessary think time checking
cfq-iosched: Don't clear queue stats when preempt.
blk-throttle: Reset group slice when limits are changed
blk-cgroup: Only give unaccounted_time under debug
cfq-iosched: Don't set active queue in preempt
block: fix non-atomic access to genhd inflight structures
block: attempt to merge with existing requests on plug flush
block: NULL dereference on error path in __blkdev_get()
cfq-iosched: Don't update group weights when on service tree
fs: assign sb->s_bdi to default_backing_dev_info if the bdi is going away
block: Require subsystems to explicitly allocate bio_set integrity mempool
jbd2: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging
jbd: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging
fs: make fsync_buffers_list() plug
mm: make generic_writepages() use plugging
blk-cgroup: Add unaccounted time to timeslice_used.
block: fixup plugging stubs for !CONFIG_BLOCK
block: remove obsolete comments for blkdev_issue_zeroout.
blktrace: Use rq->cmd_flags directly in blk_add_trace_rq.
...
Fix up conflicts in fs/{aio.c,super.c}
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With the plugging now being explicitly controlled by the
submitter, callers need not pass down unplugging hints
to the block layer. If they want to unplug, it's because they
manually plugged on their own - in which case, they should just
unplug at will.
Signed-off-by: Jens Axboe <[email protected]>
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Code has been converted over to the new explicit on-stack plugging,
and delay users have been converted to use the new API for that.
So lets kill off the old plugging along with aops->sync_page().
Signed-off-by: Jens Axboe <[email protected]>
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When using devices that support max_segments > BIO_MAX_PAGES (256), direct
IO tries to allocate a bio with more pages than allowed, which leads to an
oops in dio_bio_alloc(). Clamp the request to the supported maximum, and
change dio_bio_alloc() to reflect that bio_alloc() will always return a
bio when called with __GFP_WAIT and a valid number of vectors.
[[email protected]: remove redundant BUG_ON()]
Signed-off-by: David Dillow <[email protected]>
Reviewed-by: Jeff Moyer <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Signed-off-by: Namhyung Kim <[email protected]>
Cc: Jiri Kosina <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>
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Fix up truncation (ssize_t->int). This only matters with >2G
reads/writes, which the kernel doesn't permit.
Signed-off-by: Edward Shishkin <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Acked-by: Jeff Moyer <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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commit c2c6ca4 (direct-io: do not merge logically non-contiguous requests)
introduced a bug whereby all O_DIRECT I/Os were submitted a page at a time
to the block layer. The problem is that the code expected
dio->block_in_file to correspond to the current page in the dio. In fact,
it corresponds to the previous page submitted via submit_page_section.
This was purely an oversight, as the dio->cur_page_fs_offset field was
introduced for just this purpose. This patch simply uses the correct
variable when calculating whether there is a mismatch between contiguous
logical blocks and contiguous physical blocks (as described in the
comments).
I also switched the if conditional following this check to an else if, to
ensure that we never call dio_bio_submit twice for the same dio (in
theory, this should not happen, anyway).
I've tested this by running blktrace and verifying that a 64KB I/O was
submitted as a single I/O. I also ran the patched kernel through
xfstests' aio tests using xfs, ext4 (with 1k and 4k block sizes) and btrfs
and verified that there were no regressions as compared to an unpatched
kernel.
Signed-off-by: Jeff Moyer <[email protected]>
Acked-by: Josef Bacik <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: <[email protected]> [2.6.35.x]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Move the call to vmtruncate to get rid of accessive blocks to the callers
in prepearation of the new truncate calling sequence. This was only done
for DIO_LOCKING filesystems, so the __blockdev_direct_IO_newtrunc variant
was not needed anyway. Get rid of blockdev_direct_IO_no_locking and
its _newtrunc variant while at it as just opencoding the two additional
paramters is shorted than the name suffix.
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Al Viro <[email protected]>
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Filesystems with unwritten extent support must not complete an AIO request
until the transaction to convert the extent has been commited. That means
the aio_complete calls needs to be moved into the ->end_io callback so
that the filesystem can control when to call it exactly.
This makes a bit of a mess out of dio_complete and the ->end_io callback
prototype even more complicated.
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Alex Elder <[email protected]>
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Introduce a new truncate calling sequence into fs/mm subsystems. Rather than
setattr > vmtruncate > truncate, have filesystems call their truncate sequence
from ->setattr if filesystem specific operations are required. vmtruncate is
deprecated, and truncate_pagecache and inode_newsize_ok helpers introduced
previously should be used.
simple_setattr is introduced for simple in-ram filesystems to implement
the new truncate sequence. Eventually all filesystems should be converted
to implement a setattr, and the default code in notify_change should go
away.
simple_setsize is also introduced to perform just the ATTR_SIZE portion
of simple_setattr (ie. changing i_size and trimming pagecache).
To implement the new truncate sequence:
- filesystem specific manipulations (eg freeing blocks) must be done in
the setattr method rather than ->truncate.
- vmtruncate can not be used by core code to trim blocks past i_size in
the event of write failure after allocation, so this must be performed
in the fs code.
- convert usage of helpers block_write_begin, nobh_write_begin,
cont_write_begin, and *blockdev_direct_IO* to use _newtrunc postfixed
variants. These avoid calling vmtruncate to trim blocks (see previous).
- inode_setattr should not be used. generic_setattr is a new function
to be used to copy simple attributes into the generic inode.
- make use of the better opportunity to handle errors with the new sequence.
Big problem with the previous calling sequence: the filesystem is not called
until i_size has already changed. This means it is not allowed to fail the
call, and also it does not know what the previous i_size was. Also, generic
code calling vmtruncate to truncate allocated blocks in case of error had
no good way to return a meaningful error (or, for example, atomically handle
block deallocation).
Cc: Christoph Hellwig <[email protected]>
Acked-by: Jan Kara <[email protected]>
Signed-off-by: Nick Piggin <[email protected]>
Signed-off-by: Al Viro <[email protected]>
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Btrfs cannot handle having logically non-contiguous requests submitted. For
example if you have
Logical: [0-4095][HOLE][8192-12287]
Physical: [0-4095] [4096-8191]
Normally the DIO code would put these into the same BIO's. The problem is we
need to know exactly what offset is associated with what BIO so we can do our
checksumming and unlocking properly, so putting them in the same BIO doesn't
work. So add another check where we submit the current BIO if the physical
blocks are not contigous OR the logical blocks are not contiguous.
Signed-off-by: Josef Bacik <[email protected]>
Signed-off-by: Chris Mason <[email protected]>
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Because BTRFS can do RAID and such, we need our own submit hook so we can setup
the bio's in the correct fashion, and handle checksum errors properly. So there
are a few changes here
1) The submit_io hook. This is straightforward, just call this instead of
submit_bio.
2) Allow the fs to return -ENOTBLK for reads. Usually this has only worked for
writes, since writes can fallback onto buffered IO. But BTRFS needs the option
of falling back on buffered IO if it encounters a compressed extent, since we
need to read the entire extent in and decompress it. So if we get -ENOTBLK back
from get_block we'll return back and fallback on buffered just like the write
case.
I've tested these changes with fsx and everything seems to work. Thanks,
Signed-off-by: Josef Bacik <[email protected]>
Signed-off-by: Chris Mason <[email protected]>
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Signed-off-by: Al Viro <[email protected]>
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Currently the locking in blockdev_direct_IO is a mess, we have three
different locking types and very confusing checks for some of them. The
most complicated one is DIO_OWN_LOCKING for reads, which happens to not
actually be used.
This patch gets rid of the DIO_OWN_LOCKING - as mentioned above the read
case is unused anyway, and the write side is almost identical to
DIO_NO_LOCKING. The difference is that DIO_NO_LOCKING always sets the
create argument for the get_blocks callback to zero, but we can easily
move that to the actual get_blocks callbacks. There are four users of the
DIO_NO_LOCKING mode: gfs already ignores the create argument and thus is
fine with the new version, ocfs2 only errors out if create were ever set,
and we can remove this dead code now, the block device code only ever uses
create for an error message if we are fully beyond the device which can
never happen, and last but not least XFS will need the new behavour for
writes.
Now we can replace the lock_type variable with a flags one, where no flag
means the DIO_NO_LOCKING behaviour and DIO_LOCKING is kept as the first
flag. Separate out the check for not allowing to fill holes into a
separate flag, although for now both flags always get set at the same
time.
Also revamp the documentation of the locking scheme to actually make
sense.
[[email protected]: coding-style fixes]
Signed-off-by: Christoph Hellwig <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Badari Pulavarty <[email protected]>
Cc: Jeff Moyer <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Zach Brown <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Alex Elder <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Intel reported a performance regression caused by the following commit:
commit 848c4dd5153c7a0de55470ce99a8e13a63b4703f
Author: Zach Brown <[email protected]>
Date: Mon Aug 20 17:12:01 2007 -0700
dio: zero struct dio with kzalloc instead of manually
This patch uses kzalloc to zero all of struct dio rather than
manually trying to track which fields we rely on being zero. It
passed aio+dio stress testing and some bug regression testing on
ext3.
This patch was introduced by Linus in the conversation that lead up
to Badari's minimal fix to manually zero .map_bh.b_state in commit:
6a648fa72161d1f6468dabd96c5d3c0db04f598a
It makes the code a bit smaller. Maybe a couple fewer cachelines to
load, if we're lucky:
text data bss dec hex filename
3285925 568506 1304616 5159047 4eb887 vmlinux
3285797 568506 1304616 5158919 4eb807 vmlinux.patched
I was unable to measure a stable difference in the number of cpu
cycles spent in blockdev_direct_IO() when pushing aio+dio 256K reads
at ~340MB/s.
So the resulting intent of the patch isn't a performance gain but to
avoid exposing ourselves to the risk of finding another field like
.map_bh.b_state where we rely on zeroing but don't enforce it in the
code.
Zach surmised that zeroing out the page array was what caused most of
the problem, and suggested the approach taken in the attached patch for
resolving the issue. Intel re-tested with this patch and saw a 0.6%
performance gain (the original regression was 0.5%).
[[email protected]: add comment]
Signed-off-by: Jeff Moyer <[email protected]>
Acked-by: Zach Brown <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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There seems to be a regression in direct write path due to following
commit in for-2.6.33 branch of block tree.
commit 1af60fbd759d31f565552fea315c2033947cfbe6
Author: Jeff Moyer <[email protected]>
Date: Fri Oct 2 18:56:53 2009 -0400
block: get rid of the WRITE_ODIRECT flag
Marking direct writes as WRITE_SYNC_PLUG instead of WRITE_ODIRECT, sets
the NOIDLE flag in bio and hence in request. This tells CFQ to not expect
more request from the queue and not idle on it (despite the fact that
queue's think time is less and it is not seeky).
So direct writers lose big time when competing with sequential readers.
Using fio, I have run one direct writer and two sequential readers and
following are the results with 2.6.32-rc7 kernel and with for-2.6.33
branch.
Test
====
1 direct writer and 2 sequential reader running simultaneously.
[global]
directory=/mnt/sdc/fio/
runtime=10
[seqwrite]
rw=write
size=4G
direct=1
[seqread]
rw=read
size=2G
numjobs=2
2.6.32-rc7
==========
direct writes: aggrb=2,968KB/s
readers : aggrb=101MB/s
for-2.6.33 branch
=================
direct write: aggrb=19KB/s
readers aggrb=137MB/s
This patch brings back the WRITE_ODIRECT flag, with the difference that we
don't set the BIO_RW_UNPLUG flag so that device is not unplugged after
submission of request and an explicit unplug from submitter is required.
That way we fix the jeff's issue of not enough merging taking place in aio
path as well as make sure direct writes get their fair share.
After the fix
=============
for-2.6.33 + fix
----------------
direct writes: aggrb=2,728KB/s
reads: aggrb=103MB/s
Thanks
Vivek
Signed-off-by: Vivek Goyal <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Hi,
Some workloads issue batches of small I/O, and the performance is poor
due to the call to blk_run_address_space for every single iocb. Nathan
Roberts pointed this out, and suggested that by deferring this call
until all I/Os in the iocb array are submitted to the block layer, we
can realize some impressive performance gains (up to 30% for sequential
4k reads in batches of 16).
Signed-off-by: Jeff Moyer <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Hi,
The WRITE_ODIRECT flag is only used in one place, and that code path
happens to also call blk_run_address_space. The introduction of this
flag, then, could result in the device being unplugged twice for every
I/O.
Further, with the batching changes in the next patch, we don't want an
O_DIRECT write to imply a queue unplug.
Signed-off-by: Jeff Moyer <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Until now we have had a 1:1 mapping between storage device physical
block size and the logical block sized used when addressing the device.
With SATA 4KB drives coming out that will no longer be the case. The
sector size will be 4KB but the logical block size will remain
512-bytes. Hence we need to distinguish between the physical block size
and the logical ditto.
This patch renames hardsect_size to logical_block_size.
Signed-off-by: Martin K. Petersen <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Remove code handling bio_alloc failure with __GFP_WAIT.
GFP_KERNEL implies __GFP_WAIT.
Signed-off-by: Nikanth Karthikesan <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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By default, CFQ will anticipate more IO from a given io context if the
previously completed IO was sync. This used to be fine, since the only
sync IO was reads and O_DIRECT writes. But with more "normal" sync writes
being used now, we don't want to anticipate for those.
Add a bio/request flag that informs the IO scheduler that this is a sync
request that we should not idle for. Introduce WRITE_ODIRECT specifically
for O_DIRECT writes, and make sure that the other sync writes set this
flag.
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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