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2014-12-13mm: fadvise: document the fadvise(FADV_DONTNEED) behaviour for partial pagesMel Gorman
A random seek IO benchmark appeared to regress because of a change to readahead but the real problem was the benchmark. To ensure the IO request accesssed disk, it used fadvise(FADV_DONTNEED) on a block boundary (512K) but the hint is ignored by the kernel. This is correct but not necessarily obvious behaviour. As much as I dislike comment patches, the explanation for this behaviour predates current git history. Clarify why it behaves like this in case someone "fixes" fadvise or readahead for the wrong reasons. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-03-03teach SYSCALL_DEFINE<n> how to deal with long long/unsigned long longAl Viro
... and convert a bunch of SYSCALL_DEFINE ones to SYSCALL_DEFINE<n>, killing the boilerplate crap around them. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-26Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs pile (part one) from Al Viro: "Assorted stuff - cleaning namei.c up a bit, fixing ->d_name/->d_parent locking violations, etc. The most visible changes here are death of FS_REVAL_DOT (replaced with "has ->d_weak_revalidate()") and a new helper getting from struct file to inode. Some bits of preparation to xattr method interface changes. Misc patches by various people sent this cycle *and* ocfs2 fixes from several cycles ago that should've been upstream right then. PS: the next vfs pile will be xattr stuff." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (46 commits) saner proc_get_inode() calling conventions proc: avoid extra pde_put() in proc_fill_super() fs: change return values from -EACCES to -EPERM fs/exec.c: make bprm_mm_init() static ocfs2/dlm: use GFP_ATOMIC inside a spin_lock ocfs2: fix possible use-after-free with AIO ocfs2: Fix oops in ocfs2_fast_symlink_readpage() code path get_empty_filp()/alloc_file() leave both ->f_pos and ->f_version zero target: writev() on single-element vector is pointless export kernel_write(), convert open-coded instances fs: encode_fh: return FILEID_INVALID if invalid fid_type kill f_vfsmnt vfs: kill FS_REVAL_DOT by adding a d_weak_revalidate dentry op nfsd: handle vfs_getattr errors in acl protocol switch vfs_getattr() to struct path default SET_PERSONALITY() in linux/elf.h ceph: prepopulate inodes only when request is aborted d_hash_and_lookup(): export, switch open-coded instances 9p: switch v9fs_set_create_acl() to inode+fid, do it before d_instantiate() 9p: split dropping the acls from v9fs_set_create_acl() ...
2013-02-23mm/fadvise.c: drain all pagevecs if POSIX_FADV_DONTNEED fails to discard all ↵Mel Gorman
pages Rob van der Heij reported the following (paraphrased) on private mail. The scenario is that I want to avoid backups to fill up the page cache and purge stuff that is more likely to be used again (this is with s390x Linux on z/VM, so I don't give it as much memory that we don't care anymore). So I have something with LD_PRELOAD that intercepts the close() call (from tar, in this case) and issues a posix_fadvise() just before closing the file. This mostly works, except for small files (less than 14 pages) that remains in page cache after the face. Unfortunately Rob has not had a chance to test this exact patch but the test program below should be reproducing the problem he described. The issue is the per-cpu pagevecs for LRU additions. If the pages are added by one CPU but fadvise() is called on another then the pages remain resident as the invalidate_mapping_pages() only drains the local pagevecs via its call to pagevec_release(). The user-visible effect is that a program that uses fadvise() properly is not obeyed. A possible fix for this is to put the necessary smarts into invalidate_mapping_pages() to globally drain the LRU pagevecs if a pagevec page could not be discarded. The downside with this is that an inode cache shrink would send a global IPI and memory pressure potentially causing global IPI storms is very undesirable. Instead, this patch adds a check during fadvise(POSIX_FADV_DONTNEED) to check if invalidate_mapping_pages() discarded all the requested pages. If a subset of pages are discarded it drains the LRU pagevecs and tries again. If the second attempt fails, it assumes it is due to the pages being mapped, locked or dirty and does not care. With this patch, an application using fadvise() correctly will be obeyed but there is a downside that a malicious application can force the kernel to send global IPIs and increase overhead. If accepted, I would like this to be considered as a -stable candidate. It's not an urgent issue but it's a system call that is not working as advertised which is weak. The following test program demonstrates the problem. It should never report that pages are still resident but will without this patch. It assumes that CPU 0 and 1 exist. int main() { int fd; int pagesize = getpagesize(); ssize_t written = 0, expected; char *buf; unsigned char *vec; int resident, i; cpu_set_t set; /* Prepare a buffer for writing */ expected = FILESIZE_PAGES * pagesize; buf = malloc(expected + 1); if (buf == NULL) { printf("ENOMEM\n"); exit(EXIT_FAILURE); } buf[expected] = 0; memset(buf, 'a', expected); /* Prepare the mincore vec */ vec = malloc(FILESIZE_PAGES); if (vec == NULL) { printf("ENOMEM\n"); exit(EXIT_FAILURE); } /* Bind ourselves to CPU 0 */ CPU_ZERO(&set); CPU_SET(0, &set); if (sched_setaffinity(getpid(), sizeof(set), &set) == -1) { perror("sched_setaffinity"); exit(EXIT_FAILURE); } /* open file, unlink and write buffer */ fd = open("fadvise-test-file", O_CREAT|O_EXCL|O_RDWR); if (fd == -1) { perror("open"); exit(EXIT_FAILURE); } unlink("fadvise-test-file"); while (written < expected) { ssize_t this_write; this_write = write(fd, buf + written, expected - written); if (this_write == -1) { perror("write"); exit(EXIT_FAILURE); } written += this_write; } free(buf); /* * Force ourselves to another CPU. If fadvise only flushes the local * CPUs pagevecs then the fadvise will fail to discard all file pages */ CPU_ZERO(&set); CPU_SET(1, &set); if (sched_setaffinity(getpid(), sizeof(set), &set) == -1) { perror("sched_setaffinity"); exit(EXIT_FAILURE); } /* sync and fadvise to discard the page cache */ fsync(fd); if (posix_fadvise(fd, 0, expected, POSIX_FADV_DONTNEED) == -1) { perror("posix_fadvise"); exit(EXIT_FAILURE); } /* map the file and use mincore to see which parts of it are resident */ buf = mmap(NULL, expected, PROT_READ, MAP_SHARED, fd, 0); if (buf == NULL) { perror("mmap"); exit(EXIT_FAILURE); } if (mincore(buf, expected, vec) == -1) { perror("mincore"); exit(EXIT_FAILURE); } /* Check residency */ for (i = 0, resident = 0; i < FILESIZE_PAGES; i++) { if (vec[i]) resident++; } if (resident != 0) { printf("Nr unexpected pages resident: %d\n", resident); exit(EXIT_FAILURE); } munmap(buf, expected); close(fd); free(vec); exit(EXIT_SUCCESS); } Signed-off-by: Mel Gorman <mgorman@suse.de> Reported-by: Rob van der Heij <rvdheij@gmail.com> Tested-by: Rob van der Heij <rvdheij@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-22new helper: file_inode(file)Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-09-26switch simple cases of fget_light to fdgetAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-09-26switch fadvise(2) to fget_light()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-31mm, fadvise: don't return -EINVAL when filesystem cannot implement fadvise()KOSAKI Motohiro
Eric Wong reported his test suite failex when /tmp is tmpfs. https://lkml.org/lkml/2012/2/24/479 Currentlt the input check of POSIX_FADV_WILLNEED has two problems. - requires a_ops->readpage. But in fact, force_page_cache_readahead() requires that the target filesystem has either ->readpage or ->readpages. - returns -EINVAL when the filesystem doesn't have ->readpage. But posix says that fadvise is merely a hint. Thus fadvise() should return 0 if filesystem has no means of implementing fadvise(). The userland application should not know nor care whcih type of filesystem backs the TMPDIR directory, as Eric pointed out. There is nothing which userspace can do to solve this error. So change the return value to 0 when filesytem doesn't support readahead. [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Signed-off-by: Eric Wong <normalperson@yhbt.net> Tested-by: Eric Wong <normalperson@yhbt.net> Reviewed-by: Wanlong Gao <gaowanlong@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-10fadvise: only initiate writeback for specified range with FADV_DONTNEEDShawn Bohrer
Previously POSIX_FADV_DONTNEED would start writeback for the entire file when the bdi was not write congested. This negatively impacts performance if the file contains dirty pages outside of the requested range. This change uses __filemap_fdatawrite_range() to only initiate writeback for the requested range. Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com> Acked-by: Johannes Weiner <jweiner@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-06readahead: introduce FMODE_RANDOM for POSIX_FADV_RANDOMWu Fengguang
This fixes inefficient page-by-page reads on POSIX_FADV_RANDOM. POSIX_FADV_RANDOM used to set ra_pages=0, which leads to poor performance: a 16K read will be carried out in 4 _sync_ 1-page reads. In other places, ra_pages==0 means - it's ramfs/tmpfs/hugetlbfs/sysfs/configfs - some IO error happened where multi-page read IO won't help or should be avoided. POSIX_FADV_RANDOM actually want a different semantics: to disable the *heuristic* readahead algorithm, and to use a dumb one which faithfully submit read IO for whatever application requests. So introduce a flag FMODE_RANDOM for POSIX_FADV_RANDOM. Note that the random hint is not likely to help random reads performance noticeably. And it may be too permissive on huge request size (its IO size is not limited by read_ahead_kb). In Quentin's report (http://lkml.org/lkml/2009/12/24/145), the overall (NFS read) performance of the application increased by 313%! Tested-by: Quentin Barnes <qbarnes+nfs@yahoo-inc.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Andi Kleen <andi@firstfloor.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: <stable@kernel.org> [2.6.33.x] Cc: <qbarnes+nfs@yahoo-inc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-16readahead: move max_sane_readahead() calls into force_page_cache_readahead()Wu Fengguang
Impact: code simplification. Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-14[CVE-2009-0029] System call wrapper special casesHeiko Carstens
System calls with an unsigned long long argument can't be converted with the standard wrappers since that would include a cast to long, which in turn means that we would lose the upper 32 bit on 32 bit architectures. Also semctl can't use the standard wrapper since it has a 'union' parameter. So we handle them as special case and add some extra wrappers instead. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2008-10-16Remove Andrew Morton's old email accountsFrancois Cami
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>
2008-04-28xip: support non-struct page backed memoryNick Piggin
Convert XIP to support non-struct page backed memory, using VM_MIXEDMAP for the user mappings. This requires the get_xip_page API to be changed to an address based one. Improve the API layering a little bit too, while we're here. This is required in order to support XIP filesystems on memory that isn't backed with struct page (but memory with struct page is still supported too). Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Carsten Otte <cotte@de.ibm.com> Cc: Jared Hulbert <jaredeh@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05check ADVICE of fadvise64_64 even if get_xip_page is givenMasatake YAMATO
I've written some test programs in ltp project. During writing I met an problem which I cannot solve in user land. So I wrote a patch for linux kernel. Please, include this patch if acceptable. The test program tests the 4th parameter of fadvise64_64: long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice); My test case calls fadvise64_64 with invalid advice value and checks errno is set to EINVAL. About the advice parameter man page says: ... Permissible values for advice include: POSIX_FADV_NORMAL ... POSIX_FADV_SEQUENTIAL ... POSIX_FADV_RANDOM ... POSIX_FADV_NOREUSE ... POSIX_FADV_WILLNEED ... POSIX_FADV_DONTNEED ... ERRORS ... EINVAL An invalid value was specified for advice. However, I got a bug report that the system call invocations in my test case returned 0 unexpectedly. I've inspected the kernel code: asmlinkage long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice) { struct file *file = fget(fd); struct address_space *mapping; struct backing_dev_info *bdi; loff_t endbyte; /* inclusive */ pgoff_t start_index; pgoff_t end_index; unsigned long nrpages; int ret = 0; if (!file) return -EBADF; if (S_ISFIFO(file->f_path.dentry->d_inode->i_mode)) { ret = -ESPIPE; goto out; } mapping = file->f_mapping; if (!mapping || len < 0) { ret = -EINVAL; goto out; } if (mapping->a_ops->get_xip_page) /* no bad return value, but ignore advice */ goto out; ... out: fput(file); return ret; } I found the advice parameter is just ignored in the case mapping->a_ops->get_xip_page is given. This behavior is different from what is written on the man page. Is this o.k.? get_xip_page is given if CONFIG_EXT2_FS_XIP is true. Anyway I cannot find the easy way to detect get_xip_page field is given or CONFIG_EXT2_FS_XIP is true from the user space. I propose the following patch which checks the advice parameter even if get_xip_page is given. Signed-off-by: Masatake YAMATO <yamato@redhat.com> Acked-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-12-08[PATCH] mm: change uses of f_{dentry,vfsmnt} to use f_pathJosef "Jeff" Sipek
Change all the uses of f_{dentry,vfsmnt} to f_path.{dentry,mnt} in linux/mm/. Signed-off-by: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-08-06[PATCH] fadvise() make POSIX_FADV_NOREUSE a no-opAndrew Morton
The POSIX_FADV_NOREUSE hint means "the application will use this range of the file a single time". It seems to be intended that the implementation will use this hint to perform drop-behind of that part of the file when the application gets around to reading or writing it. However for reasons which aren't obvious (or sane?) I mapped POSIX_FADV_NOREUSE onto POSIX_FADV_WILLNEED. ie: it does readahead. That's daft. So for now, make POSIX_FADV_NOREUSE a no-op. This is a non-back-compatible change. If someone was using POSIX_FADV_NOREUSE to perform readahead, they lose. The likelihood is low. If/when we later implement POSIX_FADV_NOREUSE things will get interesting - to do it fully we'll need to maintain file offset/length ranges and peform all sorts of complex tricks, and managing the lifetime of those ranges' data structures will be interesting.. A sensible implementation would probably ignore the file range and would simply mark the entire file as needing some form of drop-behind treatment. Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-10[PATCH] fadvise: remove dead commentsAndrew Morton
Cc: "Michael Kerrisk" <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-31[PATCH] sys_sync_file_range()Andrew Morton
Remove the recently-added LINUX_FADV_ASYNC_WRITE and LINUX_FADV_WRITE_WAIT fadvise() additions, do it in a new sys_sync_file_range() syscall instead. Reasons: - It's more flexible. Things which would require two or three syscalls with fadvise() can be done in a single syscall. - Using fadvise() in this manner is something not covered by POSIX. The patch wires up the syscall for x86. The sycall is implemented in the new fs/sync.c. The intention is that we can move sys_fsync(), sys_fdatasync() and perhaps sys_sync() into there later. Documentation for the syscall is in fs/sync.c. A test app (sync_file_range.c) is in http://www.zip.com.au/~akpm/linux/patches/stuff/ext3-tools.tar.gz. The available-to-GPL-modules do_sync_file_range() is for knfsd: "A COMMIT can say NFS_DATA_SYNC or NFS_FILE_SYNC. I can skip the ->fsync call for NFS_DATA_SYNC which is hopefully the more common." Note: the `async' writeout mode SYNC_FILE_RANGE_WRITE will turn synchronous if the queue is congested. This is trivial to fix: add a new flag bit, set wbc->nonblocking. But I'm not sure that we want to expose implementation details down to that level. Note: it's notable that we can sync an fd which wasn't opened for writing. Same with fsync() and fdatasync()). Note: the code takes some care to handle attempts to sync file contents outside the 16TB offset on 32-bit machines. It makes such attempts appear to succeed, for best 32-bit/64-bit compatibility. Perhaps it should make such requests fail... Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Cc: Ulrich Drepper <drepper@redhat.com> Cc: Neil Brown <neilb@cse.unsw.edu.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-24[PATCH] fadvise(): write commandsAndrew Morton
Add two new linux-specific fadvise extensions(): LINUX_FADV_ASYNC_WRITE: start async writeout of any dirty pages between file offsets `offset' and `offset+len'. Any pages which are currently under writeout are skipped, whether or not they are dirty. LINUX_FADV_WRITE_WAIT: wait upon writeout of any dirty pages between file offsets `offset' and `offset+len'. By combining these two operations the application may do several things: LINUX_FADV_ASYNC_WRITE: push some or all of the dirty pages at the disk. LINUX_FADV_WRITE_WAIT, LINUX_FADV_ASYNC_WRITE: push all of the currently dirty pages at the disk. LINUX_FADV_WRITE_WAIT, LINUX_FADV_ASYNC_WRITE, LINUX_FADV_WRITE_WAIT: push all of the currently dirty pages at the disk, wait until they have been written. It should be noted that none of these operations write out the file's metadata. So unless the application is strictly performing overwrites of already-instantiated disk blocks, there are no guarantees here that the data will be available after a crash. To complete this suite of operations I guess we should have a "sync file metadata only" operation. This gives applications access to all the building blocks needed for all sorts of sync operations. But sync-metadata doesn't fit well with the fadvise() interface. Probably it should be a new syscall: sys_fmetadatasync(). The patch also diddles with the meaning of `endbyte' in sys_fadvise64_64(). It is made to represent that last affected byte in the file (ie: it is inclusive). Generally, all these byterange and pagerange functions are inclusive so we can easily represent EOF with -1. As Ulrich notes, these two functions are somewhat abusive of the fadvise() concept, which appears to be "set the future policy for this fd". But these commands are a perfect fit with the fadvise() impementation, and several of the existing fadvise() commands are synchronous and don't affect future policy either. I think we can live with the slight incongruity. Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] fadvise: return ESPIPE on FIFO/pipeValentine Barshak
The patch makes posix_fadvise return ESPIPE on FIFO/pipe in order to be fully POSIX-compliant. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-24[PATCH] xip: madvice/fadvice: execute in placeCarsten Otte
Make sys_madvice/fadvice return sane with xip. 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>
2005-04-16Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds
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!