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* dio: fix use-after-freeAl Viro2009-12-171-1/+1
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* direct-io: cleanup blockdev_direct_IO lockingChristoph Hellwig2009-12-161-77/+52
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Dave Chinner <david@fromorbit.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Zach Brown <zach.brown@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Alex Elder <aelder@sgi.com> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <joel.becker@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dio: don't zero out the pages array inside struct dioJeff Moyer2009-12-161-13/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Intel reported a performance regression caused by the following commit: commit 848c4dd5153c7a0de55470ce99a8e13a63b4703f Author: Zach Brown <zach.brown@oracle.com> 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%). [akpm@linux-foundation.org: add comment] Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Acked-by: Zach Brown <zach.brown@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Fix regression in direct writes performance due to WRITE_ODIRECT flag removalVivek Goyal2009-11-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <jmoyer@redhat.com> 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 <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* aio: implement request batchingJeff Moyer2009-10-281-4/+4
| | | | | | | | | | | | | | 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 <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: get rid of the WRITE_ODIRECT flagJeff Moyer2009-10-281-1/+1
| | | | | | | | | | | | | | | 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 <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: Do away with the notion of hardsect_sizeMartin K. Petersen2009-05-221-1/+1
| | | | | | | | | | | | | | 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 <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* dio: Remove code handling bio_alloc failure with __GFP_WAITNikanth Karthikesan2009-04-151-2/+0
| | | | | | | | Remove code handling bio_alloc failure with __GFP_WAIT. GFP_KERNEL implies __GFP_WAIT. Signed-off-by: Nikanth Karthikesan <knikanth@suse.de> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: Add flag for telling the IO schedulers NOT to anticipate more IOJens Axboe2009-04-061-1/+1
| | | | | | | | | | | | | | | 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 <jens.axboe@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs: truncate blocks outside i_size after O_DIRECT write errorDmitri Monakhov2009-01-061-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In case of error extending write may have instantiated a few blocks outside i_size. We need to trim these blocks. We have to do it *regardless* to blocksize. At least ext2, ext3 and reiserfs interpret (i_size < biggest block) condition as error. Fsck will complain about wrong i_size. Then fsck will fix the error by changing i_size according to the biggest block. This is bad because this blocks contain garbage from previous write attempt. And result in data corruption. ####TESTCASE_BEGIN $touch /mnt/test/BIG_FILE ## at this moment /mnt/test/BIG_FILE size and blocks equal to zero open("/mnt/test/BIG_FILE", O_WRONLY|O_CREAT|O_DIRECT, 0666) = 3 write(3, "aaaaaaaaaaaa"..., 104857600) = -1 ENOSPC (No space left on device) ## size and block sould't be changed because write op failed. $stat /mnt/test/BIG_FILE File: `/mnt/test/BIG_FILE' Size: 0 Blocks: 110896 IO Block: 1024 regular empty file <<<<<<<<^^^^^^^^^^^^^^^^^^^^^^^^^^^^^file size is less than biggest block idx Device: fe07h/65031d Inode: 14 Links: 1 Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root) Access: 2007-01-24 20:03:38.000000000 +0300 Modify: 2007-01-24 20:03:38.000000000 +0300 Change: 2007-01-24 20:03:39.000000000 +0300 #fsck.ext3 -f /dev/VG/test e2fsck 1.39 (29-May-2006) Pass 1: Checking inodes, blocks, and sizes Inode 14, i_size is 0, should be 56556544. Fix<y>? yes Pass 2: Checking directory structure .... #####TESTCASE_ENDdiff --git a/fs/direct-io.c b/fs/direct-io.c index af0558d..4e88bea 100644 [akpm@linux-foundation.org: use i_size_read()] Signed-off-by: Dmitri Monakhov <dmonakhov@openvz.org> Cc: Zach Brown <zach.brown@oracle.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Remove Andrew Morton's old email accountsFrancois Cami2008-10-161-2/+2
| | | | | | | | | People can use the real name an an index into MAINTAINERS to find the current email address. Signed-off-by: Francois Cami <francois.cami@free.fr> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dio: use get_user_pages_fastNick Piggin2008-07-261-8/+2
| | | | | | | | | | | | | | | | | | Use get_user_pages_fast in the common/generic block and fs direct IO paths. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Andi Kleen <andi@firstfloor.org> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Zach Brown <zach.brown@oracle.com> Cc: Jens Axboe <jens.axboe@oracle.com> Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Pagecache zeroing: zero_user_segment, zero_user_segments and zero_userChristoph Lameter2008-02-051-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Simplify page cache zeroing of segments of pages through 3 functions zero_user_segments(page, start1, end1, start2, end2) Zeros two segments of the page. It takes the position where to start and end the zeroing which avoids length calculations and makes code clearer. zero_user_segment(page, start, end) Same for a single segment. zero_user(page, start, length) Length variant for the case where we know the length. We remove the zero_user_page macro. Issues: 1. Its a macro. Inline functions are preferable. 2. The KM_USER0 macro is only defined for HIGHMEM. Having to treat this special case everywhere makes the code needlessly complex. The parameter for zeroing is always KM_USER0 except in one single case that we open code. Avoiding KM_USER0 makes a lot of code not having to be dealing with the special casing for HIGHMEM anymore. Dealing with kmap is only necessary for HIGHMEM configurations. In those configurations we use KM_USER0 like we do for a series of other functions defined in highmem.h. Since KM_USER0 is depends on HIGHMEM the existing zero_user_page function could not be a macro. zero_user_* functions introduced here can be be inline because that constant is not used when these functions are called. Also extract the flushing of the caches to be outside of the kmap. [akpm@linux-foundation.org: fix nfs and ntfs build] [akpm@linux-foundation.org: fix ntfs build some more] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Steven French <sfrench@us.ibm.com> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Cc: <linux-ext4@vger.kernel.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: Mark Fasheh <mark.fasheh@oracle.com> Cc: David Chinner <dgc@sgi.com> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Cc: Steven French <sfrench@us.ibm.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* remove ZERO_PAGENick Piggin2007-10-161-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The commit b5810039a54e5babf428e9a1e89fc1940fabff11 contains the note A last caveat: the ZERO_PAGE is now refcounted and managed with rmap (and thus mapcounted and count towards shared rss). These writes to the struct page could cause excessive cacheline bouncing on big systems. There are a number of ways this could be addressed if it is an issue. And indeed this cacheline bouncing has shown up on large SGI systems. There was a situation where an Altix system was essentially livelocked tearing down ZERO_PAGE pagetables when an HPC app aborted during startup. This situation can be avoided in userspace, but it does highlight the potential scalability problem with refcounting ZERO_PAGE, and corner cases where it can really hurt (we don't want the system to livelock!). There are several broad ways to fix this problem: 1. add back some special casing to avoid refcounting ZERO_PAGE 2. per-node or per-cpu ZERO_PAGES 3. remove the ZERO_PAGE completely I will argue for 3. The others should also fix the problem, but they result in more complex code than does 3, with little or no real benefit that I can see. Why? Inserting a ZERO_PAGE for anonymous read faults appears to be a false optimisation: if an application is performance critical, it would not be doing many read faults of new memory, or at least it could be expected to write to that memory soon afterwards. If cache or memory use is critical, it should not be working with a significant number of ZERO_PAGEs anyway (a more compact representation of zeroes should be used). As a sanity check -- mesuring on my desktop system, there are never many mappings to the ZERO_PAGE (eg. 2 or 3), thus memory usage here should not increase much without it. When running a make -j4 kernel compile on my dual core system, there are about 1,000 mappings to the ZERO_PAGE created per second, but about 1,000 ZERO_PAGE COW faults per second (less than 1 ZERO_PAGE mapping per second is torn down without being COWed). So removing ZERO_PAGE will save 1,000 page faults per second when running kbuild, while keeping it only saves less than 1 page clearing operation per second. 1 page clear is cheaper than a thousand faults, presumably, so there isn't an obvious loss. Neither the logical argument nor these basic tests give a guarantee of no regressions. However, this is a reasonable opportunity to try to remove the ZERO_PAGE from the pagefault path. If it is found to cause regressions, we can reintroduce it and just avoid refcounting it. The /dev/zero ZERO_PAGE usage and TLB tricks also get nuked. I don't see much use to them except on benchmarks. All other users of ZERO_PAGE are converted just to use ZERO_PAGE(0) for simplicity. We can look at replacing them all and maybe ripping out ZERO_PAGE completely when we are more satisfied with this solution. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus "snif" Torvalds <torvalds@linux-foundation.org>
* Drop 'size' argument from bio_endio and bi_end_ioNeilBrown2007-10-101-11/+2
| | | | | | | | | | | | | As bi_end_io is only called once when the reqeust is complete, the 'size' argument is now redundant. Remove it. Now there is no need for bio_endio to subtract the size completed from bi_size. So don't do that either. While we are at it, change bi_end_io to return void. Signed-off-by: Neil Brown <neilb@suse.de> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* dio: zero struct dio with kzalloc instead of manuallyZach Brown2007-08-201-17/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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. Signed-off-by: Zach Brown <zach.brown@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* direct-io: fix error-path crashesBadari Pulavarty2007-08-111-0/+1
| | | | | | | | | | | | | | | | | | | Need to initialize map_bh.b_state to zero. Otherwise, in case of a faulty user-buffer its possible to go into dio_zero_block() and submit a page by mistake - since it checks for buffer_new(). http://marc.info/?l=linux-kernel&m=118551339032528&w=2 akpm: Linus had a (better) patch to just do a kzalloc() in there, but it got lost. Probably this version is better for -stable anwyay. Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com> Acked-by: Joe Jin <joe.jin@oracle.com> Acked-by: Zach Brown <zach.brown@oracle.com> Cc: gurudas pai <gurudas.pai@oracle.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dio: remove bogus refcounting BUG_ONZach Brown2007-07-031-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | Badari Pulavarty reported a case of this BUG_ON is triggering during testing. It's completely bogus and should be removed. It's trying to notice if we left references to the dio hanging around in the sync case. They should have been dropped as IO completed while this path was in dio_await_completion(). This condition will also be checked, via some twisty logic, by the BUG_ON(ret != -EIOCBQUEUED) a few lines lower. So to start this BUG_ON() is redundant. More fatally, it's dereferencing dio-> after having dropped its reference. It's only safe to dereference the dio after releasing the lock if the final reference was just dropped. Another CPU might free the dio in bio completion and reuse the memory after this path drops the dio lock but before the BUG_ON() is evaluated. This patch passed aio+dio regression unit tests and aio-stress on ext3. Signed-off-by: Zach Brown <zach.brown@oracle.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivialLinus Torvalds2007-05-091-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial: (25 commits) sound: convert "sound" subdirectory to UTF-8 MAINTAINERS: Add cxacru website/mailing list include files: convert "include" subdirectory to UTF-8 general: convert "kernel" subdirectory to UTF-8 documentation: convert the Documentation directory to UTF-8 Convert the toplevel files CREDITS and MAINTAINERS to UTF-8. remove broken URLs from net drivers' output Magic number prefix consistency change to Documentation/magic-number.txt trivial: s/i_sem /i_mutex/ fix file specification in comments drivers/base/platform.c: fix small typo in doc misc doc and kconfig typos Remove obsolete fat_cvf help text Fix occurrences of "the the " Fix minor typoes in kernel/module.c Kconfig: Remove reference to external mqueue library Kconfig: A couple of grammatical fixes in arch/i386/Kconfig Correct comments in genrtc.c to refer to correct /proc file. Fix more "deprecated" spellos. Fix "deprecated" typoes. ... Fix trivial comment conflict in kernel/relay.c.
| * Fix misspellings collected by members of KJ list.Robert P. J. Day2007-05-091-1/+1
| | | | | | | | | | | | | | | | Fix the misspellings of "propogate", "writting" and (oh, the shame :-) "kenrel" in the source tree. Signed-off-by: Robert P. J. Day <rpjday@mindspring.com> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* | fs: convert core functions to zero_user_pageNate Diller2007-05-091-6/+2
|/ | | | | | | | | | | | | | | | | | | | | | It's very common for file systems to need to zero part or all of a page, the simplist way is just to use kmap_atomic() and memset(). There's actually a library function in include/linux/highmem.h that does exactly that, but it's confusingly named memclear_highpage_flush(), which is descriptive of *how* it does the work rather than what the *purpose* is. So this patchset renames the function to zero_user_page(), and calls it from the various places that currently open code it. This first patch introduces the new function call, and converts all the core kernel callsites, both the open-coded ones and the old memclear_highpage_flush() ones. Following this patch is a series of conversions for each file system individually, per AKPM, and finally a patch deprecating the old call. The diffstat below shows the entire patchset. [akpm@linux-foundation.org: fix a few things] Signed-off-by: Nate Diller <nate.diller@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] dio: lock refcount operationsZach Brown2006-12-101-31/+45
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The wait_for_more_bios() function name was poorly chosen. While looking to clean it up it I noticed that the dio struct refcounting between the bio completion and dio submission paths was racey. The bio submission path was simply freeing the dio struct if atomic_dec_and_test() indicated that it dropped the final reference. The aio bio completion path was dereferencing its dio struct pointer *after dropping its reference* based on the remaining number of references. These two paths could race and result in the aio bio completion path dereferencing a freed dio, though this was not observed in the wild. This moves the refcount under the bio lock so that bio completion can drop its reference and decide to wake all in one atomic step. Once testing and waking is locked dio_await_one() can test its sleeping condition and mark itself uninterruptible under the lock. It gets simpler and wait_for_more_bios() disappears. The addition of the interrupt masking spin lock acquiry in dio_bio_submit() looks alarming. This lock acquiry existed in that path before the recent dio completion patch set. We shouldn't expect significant performance regression from returning to the behaviour that existed before the completion clean up work. This passed 4k block ext3 O_DIRECT fsx and aio-stress on an SMP machine. Signed-off-by: Zach Brown <zach.brown@oracle.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Suparna Bhattacharya <suparna@in.ibm.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: <xfs-masters@oss.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dio: only call aio_complete() after returning -EIOCBQUEUEDZach Brown2006-12-101-55/+35
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The only time it is safe to call aio_complete() is when the ->ki_retry function returns -EIOCBQUEUED to the AIO core. direct_io_worker() has historically done this by relying on its caller to translate positive return codes into -EIOCBQUEUED for the aio case. It did this by trying to keep conditionals in sync. direct_io_worker() knew when finished_one_bio() was going to call aio_complete(). It would reverse the test and wait and free the dio in the cases it thought that finished_one_bio() wasn't going to. Not surprisingly, it ended up getting it wrong. 'ret' could be a negative errno from the submission path but it failed to communicate this to finished_one_bio(). direct_io_worker() would return < 0, it's callers wouldn't raise -EIOCBQUEUED, and aio_complete() would be called. In the future finished_one_bio()'s tests wouldn't reflect this and aio_complete() would be called for a second time which can manifest as an oops. The previous cleanups have whittled the sync and async completion paths down to the point where we can collapse them and clearly reassert the invariant that we must only call aio_complete() after returning -EIOCBQUEUED. direct_io_worker() will only return -EIOCBQUEUED when it is not the last to drop the dio refcount and the aio bio completion path will only call aio_complete() when it is the last to drop the dio refcount. direct_io_worker() can ensure that it is the last to drop the reference count by waiting for bios to drain. It does this for sync ops, of course, and for partial dio writes that must fall back to buffered and for aio ops that saw errors during submission. This means that operations that end up waiting, even if they were issued as aio ops, will not call aio_complete() from dio. Instead we return the return code of the operation and let the aio core call aio_complete(). This is purposely done to fix a bug where AIO DIO file extensions would call aio_complete() before their callers have a chance to update i_size. Now that direct_io_worker() is explicitly returning -EIOCBQUEUED its callers no longer have to translate for it. XFS needs to be careful not to free resources that will be used during AIO completion if -EIOCBQUEUED is returned. We maintain the previous behaviour of trying to write fs metadata for O_SYNC aio+dio writes. Signed-off-by: Zach Brown <zach.brown@oracle.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Suparna Bhattacharya <suparna@in.ibm.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Cc: <xfs-masters@oss.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dio: remove duplicate bio wait codeZach Brown2006-12-101-29/+12
| | | | | | | | | | | | | | | | | | | | Now that we have a single refcount and waiting path we can reuse it in the async 'should_wait' path. It continues to rely on the fragile link between the conditional in dio_complete_aio() which decides to complete the AIO and the conditional in direct_io_worker() which decides to wait and free. By waiting before dropping the reference we stop dio_bio_end_aio() from calling dio_complete_aio() which used to wake up the waiter after seeing the reference count drop to 0. We hoist this wake up into dio_bio_end_aio() which now notices when it's left a single remaining reference that is held by the waiter. Signed-off-by: Zach Brown <zach.brown@oracle.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Suparna Bhattacharya <suparna@in.ibm.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dio: formalize bio counters as a dio reference countZach Brown2006-12-101-74/+66
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously we had two confusing counts of bio progress. 'bio_count' was decremented as bios were processed and freed by the dio core. It was used to indicate final completion of the dio operation. 'bios_in_flight' reflected how many bios were between submit_bio() and bio->end_io. It was used by the sync path to decide when to wake up and finish completing bios and was ignored by the async path. This patch collapses the two notions into one notion of a dio reference count. bios hold a dio reference when they're between submit_bio and bio->end_io. Since bios_in_flight was only used in the sync path it is now equivalent to dio->refcount - 1 which accounts for direct_io_worker() holding a reference for the duration of the operation. dio_bio_complete() -> finished_one_bio() was called from the sync path after finding bios on the list that the bio->end_io function had deposited. finished_one_bio() can not drop the dio reference on behalf of these bios now because bio->end_io already has. The is_async test in finished_one_bio() meant that it never actually did anything other than drop the bio_count for sync callers. So we remove its refcount decrement, don't call it from dio_bio_complete(), and hoist its call up into the async dio_bio_complete() caller after an explicit refcount decrement. It is renamed dio_complete_aio() to reflect the remaining work it actually does. Signed-off-by: Zach Brown <zach.brown@oracle.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Suparna Bhattacharya <suparna@in.ibm.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dio: call blk_run_address_space() once per opZach Brown2006-12-101-5/+3
| | | | | | | | | | | | | | | | | We only need to call blk_run_address_space() once after all the bios for the direct IO op have been submitted. This removes the chance of calling blk_run_address_space() after spurious wake ups as the sync path waits for bios to drain. It's also one less difference betwen the sync and async paths. In the process we remove a redundant dio_bio_submit() that its caller had already performed. Signed-off-by: Zach Brown <zach.brown@oracle.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Suparna Bhattacharya <suparna@in.ibm.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dio: centralize completion in dio_complete()Zach Brown2006-12-101-52/+42
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There have been a lot of bugs recently due to the way direct_io_worker() tries to decide how to finish direct IO operations. In the worst examples it has failed to call aio_complete() at all (hang) or called it too many times (oops). This set of patches cleans up the completion phase with the goal of removing the complexity that lead to these bugs. We end up with one path that calculates the result of the operation after all off the bios have completed. We decide when to generate a result of the operation using that path based on the final release of a refcount on the dio structure. I tried to progress towards the final state in steps that were relatively easy to understand. Each step should compile but I only tested the final result of having all the patches applied. I've tested these on low end PC drives with aio-stress, the direct IO tests I could manage to get running in LTP, orasim, and some home-brew functional tests. In http://lkml.org/lkml/2006/9/21/103 IBM reports success with ext2 and ext3 running DIO LTP tests. They found that XFS bug which has since been addressed in the patch series. This patch: The mechanics which decide the result of a direct IO operation were duplicated in the sync and async paths. The async path didn't check page_errors which can manifest as silently returning success when the final pointer in an operation faults and its matching file region is filled with zeros. The sync path and async path differed in whether they passed errors to the caller's dio->end_io operation. The async path was passing errors to it which trips an assertion in XFS, though it is apparently harmless. This centralizes the completion phase of dio ops in one place. AIO will now return EFAULT consistently and all paths fall back to the previously sync behaviour of passing the number of bytes 'transferred' to the dio->end_io callback, regardless of errors. dio_await_completion() doesn't have to propogate EIO from non-uptodate bios now that it's being propogated through dio_complete() via dio->io_error. This lets it return void which simplifies its sole caller. Signed-off-by: Zach Brown <zach.brown@oracle.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Suparna Bhattacharya <suparna@in.ibm.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] io-accounting: direct-ioAndrew Morton2006-12-101-0/+8
| | | | | | | | | | | | | | Account for direct-io. Cc: Jay Lan <jlan@sgi.com> Cc: Shailabh Nagar <nagar@watson.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Chris Sturtivant <csturtiv@sgi.com> Cc: Tony Ernst <tee@sgi.com> Cc: Guillaume Thouvenin <guillaume.thouvenin@bull.net> Cc: David Wright <daw@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] lockdep: annotate direct ioIngo Molnar2006-07-031-2/+4
| | | | | | | | | | | Teach special (rwsem-in-irq) locking code to the lock validator. Has no effect on non-lockdep kernels. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Kill PF_SYNCWRITE flagJens Axboe2006-06-231-10/+8
| | | | | | | | | | | | | | | A process flag to indicate whether we are doing sync io is incredibly ugly. It also causes performance problems when one does a lot of async io and then proceeds to sync it. Part of the io will go out as async, and the other part as sync. This causes a disconnect between the previously submitted io and the synced io. For io schedulers such as CFQ, this will cause us lost merges and suboptimal behaviour in scheduling. Remove PF_SYNCWRITE completely from the fsync/msync paths, and let the O_DIRECT path just directly indicate that the writes are sync by using WRITE_SYNC instead. Signed-off-by: Jens Axboe <axboe@suse.de>
* BUG_ON() Conversion in fs/direct-io.cEric Sesterhenn2006-04-011-2/+1
| | | | | | | | this changes if() BUG(); constructs to BUG_ON() which is cleaner and can better optimized away Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* Fixes a regression from the recent "remove ->get_blocks() support"Nathan Scott2006-03-291-3/+4
| | | | | | | | | | change. inode->i_blkbits should be used when making a get_block_t request of a filesystem instead of dio->blkbits, as that does not indicate the filesystem block size all the time (depends on request alignment - see start of __blockdev_direct_IO). Signed-off-by: Nathan Scott <nathans@sgi.com> Acked-by: Badari Pulavarty <pbadari@us.ibm.com>
* [PATCH] remove ->get_blocks() supportBadari Pulavarty2006-03-261-13/+14
| | | | | | | | | | Now that get_block() can handle mapping multiple disk blocks, no need to have ->get_blocks(). This patch removes fs specific ->get_blocks() added for DIO and makes it users use get_block() instead. Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] direct-io: bug fix in dio handling write errorChen, Kenneth W2006-03-251-1/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a bug in direct-io on propagating write error up to the higher I/O layer. When performing an async ODIRECT write to a block device, if a device error occurred (like media error or disk is pulled), the error code is only propagated from device driver to the DIO layer. The error code stops at finished_one_bio(). The aysnc write, however, is supposedly have a corresponding AIO event with appropriate return code (in this case -EIO). Application which waits on the async write event, will hang forever since such AIO event is lost forever (if such app did not use the timeout option in io_getevents call. Regardless, an AIO event is lost). The discovery of above bug leads to another discovery of potential race window with dio->result. The fundamental problem is that dio->result is overloaded with dual use: an indicator of fall back path for partial dio write, and an error indicator used in the I/O completion path. In the event of device error, the setting of -EIO to dio->result clashes with value used to track partial write that activates the fall back path. It was also pointed out that it is impossible to use dio->result to track partial write and at the same time to track error returned from device driver. Because direct_io_work can only determines whether it is a partial write at the end of io submission and in mid stream of those io submission, a return code could be coming back from the driver. Thus messing up all the subsequent logic. Proposed fix is to separating out error code returned by the IO completion path from partial IO submit tracking. A new variable is added to dio structure specifically to track io error returned in the completion path. Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Acked-by: Zach Brown <zach.brown@oracle.com> Acked-by: Suparna Bhattacharya <suparna@in.ibm.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Fix a direct I/O locking issue revealed by the new mutex code.Nathan Scott2006-03-151-9/+12
| | | | | | | | | | | | | | | | | | | | Affects only XFS (i.e. DIO_OWN_LOCKING case) - currently it is not possible to get i_mutex locking correct when using DIO_OWN direct I/O locking in a filesystem due to indeterminism in the possible return code/lock/unlock combinations. This can cause a direct read to attempt a double i_mutex unlock inside XFS. We're now ensuring __blockdev_direct_IO always exits with the inode i_mutex (still) held for a direct reader. Tested with the three different locking modes (via direct block device access, ext3 and XFS) - both reading and writing; cannot find any regressions resulting from this change, and it clearly fixes the mutex_unlock warning originally reported here: http://marc.theaimsgroup.com/?l=linux-kernel&m=114189068126253&w=2 Signed-off-by: Nathan Scott <nathans@sgi.com> Acked-by: Christoph Hellwig <hch@lst.de>
* [PATCH] fix O_DIRECT read of last block in a sparse fileJeff Moyer2006-02-031-1/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, if you open a file O_DIRECT, truncate it to a size that is not a multiple of the disk block size, and then try to read the last block in the file, the read will return 0. The problem is in do_direct_IO, here: /* Handle holes */ if (!buffer_mapped(map_bh)) { char *kaddr; ... if (dio->block_in_file >= i_size_read(dio->inode)>>blkbits) { /* We hit eof */ page_cache_release(page); goto out; } We shift off any remaining bytes in the final block of the I/O, resulting in a 0-sized read. I've attached a patch that fixes this. I'm not happy about how ugly the math is getting, so suggestions are more than welcome. I've tested this with a simple program that performs the steps outlined for reproducing the problem above. Without the patch, we get a 0-sized result from read. With the patch, we get the correct return value from the short read. Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Suparna Bhattacharya <suparna@in.ibm.com> Cc: Mingming Cao <cmm@us.ibm.com> Cc: Joel Becker <Joel.Becker@oracle.com> Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mutex subsystem, semaphore to mutex: VFS, ->i_semJes Sorensen2006-01-091-15/+15
| | | | | | | | | | | | | This patch converts the inode semaphore to a mutex. I have tested it on XFS and compiled as much as one can consider on an ia64. Anyway your luck with it might be different. Modified-by: Ingo Molnar <mingo@elte.hu> (finished the conversion) Signed-off-by: Jes Sorensen <jes@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* [PATCH] core remove PageReservedNick Piggin2005-10-291-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Remove PageReserved() calls from core code by tightening VM_RESERVED handling in mm/ to cover PageReserved functionality. PageReserved special casing is removed from get_page and put_page. All setting and clearing of PageReserved is retained, and it is now flagged in the page_alloc checks to help ensure we don't introduce any refcount based freeing of Reserved pages. MAP_PRIVATE, PROT_WRITE of VM_RESERVED regions is tentatively being deprecated. We never completely handled it correctly anyway, and is be reintroduced in future if required (Hugh has a proof of concept). Once PageReserved() calls are removed from kernel/power/swsusp.c, and all arch/ and driver code, the Set and Clear calls, and the PG_reserved bit can be trivially removed. Last real user of PageReserved is swsusp, which uses PageReserved to determine whether a struct page points to valid memory or not. This still needs to be addressed (a generic page_is_ram() should work). A last caveat: the ZERO_PAGE is now refcounted and managed with rmap (and thus mapcounted and count towards shared rss). These writes to the struct page could cause excessive cacheline bouncing on big systems. There are a number of ways this could be addressed if it is an issue. Signed-off-by: Nick Piggin <npiggin@suse.de> Refcount bug fix for filemap_xip.c Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] pass iocb to dio_iodone_tChristoph Hellwig2005-06-241-1/+1
| | | | | | | | | XFS will have to look at iocb->private to fix aio+dio. No other filesystem is using the blockdev_direct_IO* end_io callback. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Direct IO async short read fixDaniel McNeil2005-04-161-3/+17
| | | | | | | | | | | | | | | | The direct I/O code is mapping the read request to the file system block. If the file size was not on a block boundary, the result would show the the read reading past EOF. This was only happening for the AIO case. The non-AIO case truncates the result to match file size (in direct_io_worker). This patch does the same thing for the AIO case, it truncates the result to match the file size if the read reads past EOF. When I/O completes the result can be truncated to match the file size without using i_size_read(), thus the aio result now matches the number of bytes read to the end of file. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds2005-04-161-0/+1258
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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