summaryrefslogtreecommitdiffstats
path: root/fs/read_write.c (follow)
Commit message (Collapse)AuthorAgeFilesLines
* vfs: atomic f_pos access in llseek()Eric Biggers2014-03-231-2/+2
| | | | | | | | | Commit 9c225f2655e36a4 ("vfs: atomic f_pos accesses as per POSIX") changed several system calls to use fdget_pos() instead of fdget(), but missed sys_llseek(). Fix it. Signed-off-by: Eric Biggers <ebiggers3@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* get rid of fget_light()Al Viro2014-03-101-15/+1
| | | | | | | | instead of returning the flags by reference, we can just have the low-level primitive return those in lower bits of unsigned long, with struct file * derived from the rest. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: atomic f_pos accesses as per POSIXLinus Torvalds2014-03-101-14/+40
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Our write() system call has always been atomic in the sense that you get the expected thread-safe contiguous write, but we haven't actually guaranteed that concurrent writes are serialized wrt f_pos accesses, so threads (or processes) that share a file descriptor and use "write()" concurrently would quite likely overwrite each others data. This violates POSIX.1-2008/SUSv4 Section XSI 2.9.7 that says: "2.9.7 Thread Interactions with Regular File Operations All of the following functions shall be atomic with respect to each other in the effects specified in POSIX.1-2008 when they operate on regular files or symbolic links: [...]" and one of the effects is the file position update. This unprotected file position behavior is not new behavior, and nobody has ever cared. Until now. Yongzhi Pan reported unexpected behavior to Michael Kerrisk that was due to this. This resolves the issue with a f_pos-specific lock that is taken by read/write/lseek on file descriptors that may be shared across threads or processes. Reported-by: Yongzhi Pan <panyongzhi@gmail.com> Reported-by: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs/compat: fix parameter handling for compat readv/writev syscallsHeiko Carstens2014-01-301-8/+8
| | | | | | | | | | | | | | | | | | | | | | | | We got a report that the pwritev syscall does not work correctly in compat mode on s390. It turned out that with commit 72ec35163f9f ("switch compat readv/writev variants to COMPAT_SYSCALL_DEFINE") we lost the zero extension of a couple of syscall parameters because the some parameter types haven't been converted from unsigned long to compat_ulong_t. This is needed for architectures where the ABI requires that the caller of a function performed zero and/or sign extension to 64 bit of all parameters. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Ingo Molnar <mingo@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: <stable@vger.kernel.org> [v3.10+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/read_write.c:compat_readv(): remove bogus area verifyCorey Minyard2014-01-221-4/+0
| | | | | | | | | | | | | | | The compat_do_readv_writev() function was doing a verify_area on the incoming iov, but the nr_segs value is not checked. If someone passes in a -1 for nr_segs, for instance, the function should return an EINVAL. However, it returns a EFAULT because the verify_area fails because it is checking an array of size MAX_UINT. The check is bogus, anyway, because the next check, compat_rw_copy_check_uvector(), will do all the necessary checking, anyway. The non-compat do_readv_writev() function doesn't do this check, so I think it's safe to just remove the code. Signed-off-by: Corey Minyard <cminyard@mvista.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* file->f_op is never NULL...Al Viro2013-10-251-17/+8
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* aio: Kill aio_rw_vect_retry()Kent Overstreet2013-07-301-3/+0
| | | | | | | | | | | | | | | | | | | | | | | | | This code doesn't serve any purpose anymore, since the aio retry infrastructure has been removed. This change should be safe because aio_read/write are also used for synchronous IO, and called from do_sync_read()/do_sync_write() - and there's no looping done in the sync case (the read and write syscalls). Signed-off-by: Kent Overstreet <koverstreet@google.com> Cc: Zach Brown <zab@redhat.com> Cc: Felipe Balbi <balbi@ti.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jens Axboe <axboe@kernel.dk> Cc: Asai Thambi S P <asamymuthupa@micron.com> Cc: Selvan Mani <smani@micron.com> Cc: Sam Bradshaw <sbradshaw@micron.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Benjamin LaHaise <bcrl@kvack.org> Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
* vfs: export lseek_execute() to modulesJie Liu2013-07-031-3/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For those file systems(btrfs/ext4/ocfs2/tmpfs) that support SEEK_DATA/SEEK_HOLE functions, we end up handling the similar matter in lseek_execute() to update the current file offset to the desired offset if it is valid, ceph also does the simliar things at ceph_llseek(). To reduce the duplications, this patch make lseek_execute() public accessible so that we can call it directly from the underlying file systems. Thanks Dave Chinner for this suggestion. [AV: call it vfs_setpos(), don't bring the removed 'inode' argument back] v2->v1: - Add kernel-doc comments for lseek_execute() - Call lseek_execute() in ceph->llseek() Signed-off-by: Jie Liu <jeff.liu@oracle.com> Cc: Dave Chinner <dchinner@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andi Kleen <andi@firstfloor.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Chris Mason <chris.mason@fusionio.com> Cc: Josef Bacik <jbacik@fusionio.com> Cc: Ben Myers <bpm@sgi.com> Cc: Ted Tso <tytso@mit.edu> Cc: Hugh Dickins <hughd@google.com> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Sage Weil <sage@inktank.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* lseek_execute() doesn't need an inode passed to itAl Viro2013-06-291-7/+3
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* constify rw_verify_area()Al Viro2013-06-291-1/+1
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* new helper: fixed_size_llseek()Al Viro2013-06-291-0/+20
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* don't call file_pos_write() if vfs_{read,write}{,v}() failsAl Viro2013-06-291-6/+12
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* lift file_*_write out of do_splice_direct()Al Viro2013-06-291-0/+2
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* splice: don't pass the address of ->f_pos to methodsAl Viro2013-06-201-8/+16
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* aio: don't include aio.h in sched.hKent Overstreet2013-05-081-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | Faster kernel compiles by way of fewer unnecessary includes. [akpm@linux-foundation.org: fix fallout] [akpm@linux-foundation.org: fix build] Signed-off-by: Kent Overstreet <koverstreet@google.com> Cc: Zach Brown <zab@redhat.com> Cc: Felipe Balbi <balbi@ti.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jens Axboe <axboe@kernel.dk> Cc: Asai Thambi S P <asamymuthupa@micron.com> Cc: Selvan Mani <smani@micron.com> Cc: Sam Bradshaw <sbradshaw@micron.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Benjamin LaHaise <bcrl@kvack.org> Reviewed-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* aio: remove retry-based AIOZach Brown2013-05-081-31/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This removes the retry-based AIO infrastructure now that nothing in tree is using it. We want to remove retry-based AIO because it is fundemantally unsafe. It retries IO submission from a kernel thread that has only assumed the mm of the submitting task. All other task_struct references in the IO submission path will see the kernel thread, not the submitting task. This design flaw means that nothing of any meaningful complexity can use retry-based AIO. This removes all the code and data associated with the retry machinery. The most significant benefit of this is the removal of the locking around the unused run list in the submission path. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Kent Overstreet <koverstreet@google.com> Signed-off-by: Zach Brown <zab@redhat.com> Cc: Zach Brown <zab@redhat.com> Cc: Felipe Balbi <balbi@ti.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jens Axboe <axboe@kernel.dk> Cc: Asai Thambi S P <asamymuthupa@micron.com> Cc: Selvan Mani <smani@micron.com> Cc: Sam Bradshaw <sbradshaw@micron.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Benjamin LaHaise <bcrl@kvack.org> Reviewed-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kill fs/read_write.hAl Viro2013-05-041-1/+4
| | | | | | | fs/compat.c doesn't need it anymore, so let's just move the remaining contents (two typedefs) into fs/read_write.c Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Merge branch 'for-linus' of ↵Linus Torvalds2013-05-021-2/+203
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull VFS updates from Al Viro, Misc cleanups all over the place, mainly wrt /proc interfaces (switch create_proc_entry to proc_create(), get rid of the deprecated create_proc_read_entry() in favor of using proc_create_data() and seq_file etc). 7kloc removed. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (204 commits) don't bother with deferred freeing of fdtables proc: Move non-public stuff from linux/proc_fs.h to fs/proc/internal.h proc: Make the PROC_I() and PDE() macros internal to procfs proc: Supply a function to remove a proc entry by PDE take cgroup_open() and cpuset_open() to fs/proc/base.c ppc: Clean up scanlog ppc: Clean up rtas_flash driver somewhat hostap: proc: Use remove_proc_subtree() drm: proc: Use remove_proc_subtree() drm: proc: Use minor->index to label things, not PDE->name drm: Constify drm_proc_list[] zoran: Don't print proc_dir_entry data in debug reiserfs: Don't access the proc_dir_entry in r_open(), r_start() r_show() proc: Supply an accessor for getting the data from a PDE's parent airo: Use remove_proc_subtree() rtl8192u: Don't need to save device proc dir PDE rtl8187se: Use a dir under /proc/net/r8180/ proc: Add proc_mkdir_data() proc: Move some bits from linux/proc_fs.h to linux/{of.h,signal.h,tty.h} proc: Move PDE_NET() to fs/proc/proc_net.c ...
| * lift sb_start_write() out of ->write()Al Viro2013-04-091-10/+14
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * switch compat readv/writev variants to COMPAT_SYSCALL_DEFINEAl Viro2013-04-091-2/+195
| | | | | | | | | | | | ... and take to fs/read_write.c Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * lift sb_start_write/sb_end_write out of ->aio_write()Al Viro2013-04-091-2/+6
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Merge branch 'for-linus' of ↵Linus Torvalds2013-05-011-22/+46
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal Pull compat cleanup from Al Viro: "Mostly about syscall wrappers this time; there will be another pile with patches in the same general area from various people, but I'd rather push those after both that and vfs.git pile are in." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal: syscalls.h: slightly reduce the jungles of macros get rid of union semop in sys_semctl(2) arguments make do_mremap() static sparc: no need to sign-extend in sync_file_range() wrapper ppc compat wrappers for add_key(2) and request_key(2) are pointless x86: trim sys_ia32.h x86: sys32_kill and sys32_mprotect are pointless get rid of compat_sys_semctl() and friends in case of ARCH_WANT_OLD_COMPAT_IPC merge compat sys_ipc instances consolidate compat lookup_dcookie() convert vmsplice to COMPAT_SYSCALL_DEFINE switch getrusage() to COMPAT_SYSCALL_DEFINE switch epoll_pwait to COMPAT_SYSCALL_DEFINE convert sendfile{,64} to COMPAT_SYSCALL_DEFINE switch signalfd{,4}() to COMPAT_SYSCALL_DEFINE make SYSCALL_DEFINE<n>-generated wrappers do asmlinkage_protect make HAVE_SYSCALL_WRAPPERS unconditional consolidate cond_syscall and SYSCALL_ALIAS declarations teach SYSCALL_DEFINE<n> how to deal with long long/unsigned long long get rid of duplicate logics in __SC_....[1-6] definitions
| * | convert sendfile{,64} to COMPAT_SYSCALL_DEFINEAl Viro2013-03-041-2/+42
| | | | | | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * | teach SYSCALL_DEFINE<n> how to deal with long long/unsigned long longAl Viro2013-03-041-20/+4
| | | | | | | | | | | | | | | | | | | | | ... 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>
* | | fs/read_write.c: fix generic_file_llseek() commentMing Lei2013-04-301-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit ef3d0fd27e90 ("vfs: do (nearly) lockless generic_file_llseek") has removed i_mutex from generic_file_llseek, so update the comment accordingly. Signed-off-by: Ming Lei <tom.leiming@gmail.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | vfs/splice: Fix missed checks in new __kernel_write() helperAl Viro2013-03-271-0/+3
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | Commit 06ae43f34bcc ("Don't bother with redoing rw_verify_area() from default_file_splice_from()") lost the checks to test existence of the write/aio_write methods. My apologies ;-/ Eventually, we want that in fs/splice.c side of things (no point repeating it for every buffer, after all), but for now this is the obvious minimal fix. Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | Don't bother with redoing rw_verify_area() from default_file_splice_from()Al Viro2013-03-211-0/+25
|/ | | | | | | | | | default_file_splice_from() ends up calling vfs_write() (via very convoluted callchain). It's an overkill, since we already have done rw_verify_area() in the caller by the time we call vfs_write() we are under set_fs(KERNEL_DS), so access_ok() is also pointless. Add a new helper (__kernel_write()), use it instead of kernel_write() in there. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Merge branch 'for-linus' of ↵Linus Torvalds2013-03-021-1/+8
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal Pull signal/compat fixes from Al Viro: "Fixes for several regressions introduced in the last signal.git pile, along with fixing bugs in truncate and ftruncate compat (on just about anything biarch at least one of those two had been done wrong)." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal: compat: restore timerfd settime and gettime compat syscalls [regression] braino in "sparc: convert to ksignal" fix compat truncate/ftruncate switch lseek to COMPAT_SYSCALL_DEFINE lseek() and truncate() on sparc really need sign extension
| * switch lseek to COMPAT_SYSCALL_DEFINEAl Viro2013-02-241-1/+8
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | new helper: file_inode(file)Al Viro2013-02-231-4/+4
|/ | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* sendfile: allows bypassing of notifier eventsScott Wolchok2012-12-211-0/+2
| | | | | | | | | | | | | | | | | do_sendfile() in fs/read_write.c does not call the fsnotify functions, unlike its neighbors. This manifests as a lack of inotify ACCESS events when a file is sent using sendfile(2). Addresses https://bugzilla.kernel.org/show_bug.cgi?id=12812 [akpm@linux-foundation.org: use fsnotify_modify(out.file), not fsnotify_access(), per Dave] Signed-off-by: Alan Cox <alan@linux.intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Scott Wolchok <swolchok@umich.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lseek: the "whence" argument is called "whence"Andrew Morton2012-12-181-20/+20
| | | | | | | | | But the kernel decided to call it "origin" instead. Fix most of the sites. Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* compat: fs: Generic compat_sys_sendfile implementationCatalin Marinas2012-10-031-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | This function is used by sparc, powerpc and arm64 for compat support. The patch adds a generic implementation which calls do_sendfile() directly and avoids set_fs(). The sparc architecture has wrappers for the sign extensions while powerpc relies on the compiler to do the this. The patch adds wrappers for powerpc to handle the u32->int type conversion. compat_sys_sendfile64() can be replaced by a sys_sendfile() call since compat_loff_t has the same size as off_t on a 64-bit system. On powerpc, the patch also changes the 64-bit sendfile call from sys_sendile64 to sys_sendfile. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: David S. Miller <davem@davemloft.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* switch simple cases of fget_light to fdgetAl Viro2012-09-271-99/+77
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: allow custom EOF in generic_file_llseek codeEric Sandeen2012-07-221-8/+10
| | | | | | | | | | | | | | | | | | | | | | | | For ext3/4 htree directories, using the vfs llseek function with SEEK_END goes to i_size like for any other file, but in reality we want the maximum possible hash value. Recent changes in ext4 have cut & pasted generic_file_llseek() back into fs/ext4/dir.c, but replicating this core code seems like a bad idea, especially since the copy has already diverged from the vfs. This patch updates generic_file_llseek_size to accept both a custom maximum offset, and a custom EOF position. With this in place, ext4_dir_llseek can pass in the appropriate maximum hash position for both maxsize and eof, and get what it wants. As far as I know, this does not fix any bugs - nfs in the kernel doesn't use SEEK_END, and I don't know of any user who does. But some ext4 folks seem keen on doing the right thing here, and I can't really argue. (Patch also fixes up some comments slightly) Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* aio/vfs: cleanup of rw_copy_check_uvector() and compat_rw_copy_check_uvector()Christopher Yeoh2012-06-011-4/+3
| | | | | | | | | | | | | | | | | | A cleanup of rw_copy_check_uvector and compat_rw_copy_check_uvector after changes made to support CMA in an earlier patch. Rather than having an additional check_access parameter to these functions, the first paramater type is overloaded to allow the caller to specify CHECK_IOVEC_ONLY which means check that the contents of the iovec are valid, but do not check the memory that they point to. This is used by process_vm_readv/writev where we need to validate that a iovec passed to the syscall is valid but do not want to check the memory that it points to at this point because it refers to an address space in another process. Signed-off-by: Chris Yeoh <yeohc@au1.ibm.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs: reduce the use of module.h wherever possiblePaul Gortmaker2012-02-291-1/+1
| | | | | | | | | | For files only using THIS_MODULE and/or EXPORT_SYMBOL, map them onto including export.h -- or if the file isn't even using those, then just delete the include. Fix up any implicit include dependencies that were being masked by module.h along the way. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
* Cross Memory AttachChristopher Yeoh2011-11-011-3/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The basic idea behind cross memory attach is to allow MPI programs doing intra-node communication to do a single copy of the message rather than a double copy of the message via shared memory. The following patch attempts to achieve this by allowing a destination process, given an address and size from a source process, to copy memory directly from the source process into its own address space via a system call. There is also a symmetrical ability to copy from the current process's address space into a destination process's address space. - Use of /proc/pid/mem has been considered, but there are issues with using it: - Does not allow for specifying iovecs for both src and dest, assuming preadv or pwritev was implemented either the area read from or written to would need to be contiguous. - Currently mem_read allows only processes who are currently ptrace'ing the target and are still able to ptrace the target to read from the target. This check could possibly be moved to the open call, but its not clear exactly what race this restriction is stopping (reason appears to have been lost) - Having to send the fd of /proc/self/mem via SCM_RIGHTS on unix domain socket is a bit ugly from a userspace point of view, especially when you may have hundreds if not (eventually) thousands of processes that all need to do this with each other - Doesn't allow for some future use of the interface we would like to consider adding in the future (see below) - Interestingly reading from /proc/pid/mem currently actually involves two copies! (But this could be fixed pretty easily) As mentioned previously use of vmsplice instead was considered, but has problems. Since you need the reader and writer working co-operatively if the pipe is not drained then you block. Which requires some wrapping to do non blocking on the send side or polling on the receive. In all to all communication it requires ordering otherwise you can deadlock. And in the example of many MPI tasks writing to one MPI task vmsplice serialises the copying. There are some cases of MPI collectives where even a single copy interface does not get us the performance gain we could. For example in an MPI_Reduce rather than copy the data from the source we would like to instead use it directly in a mathops (say the reduce is doing a sum) as this would save us doing a copy. We don't need to keep a copy of the data from the source. I haven't implemented this, but I think this interface could in the future do all this through the use of the flags - eg could specify the math operation and type and the kernel rather than just copying the data would apply the specified operation between the source and destination and store it in the destination. Although we don't have a "second user" of the interface (though I've had some nibbles from people who may be interested in using it for intra process messaging which is not MPI). This interface is something which hardware vendors are already doing for their custom drivers to implement fast local communication. And so in addition to this being useful for OpenMPI it would mean the driver maintainers don't have to fix things up when the mm changes. There was some discussion about how much faster a true zero copy would go. Here's a link back to the email with some testing I did on that: http://marc.info/?l=linux-mm&m=130105930902915&w=2 There is a basic man page for the proposed interface here: http://ozlabs.org/~cyeoh/cma/process_vm_readv.txt This has been implemented for x86 and powerpc, other architecture should mainly (I think) just need to add syscall numbers for the process_vm_readv and process_vm_writev. There are 32 bit compatibility versions for 64-bit kernels. For arch maintainers there are some simple tests to be able to quickly verify that the syscalls are working correctly here: http://ozlabs.org/~cyeoh/cma/cma-test-20110718.tgz Signed-off-by: Chris Yeoh <yeohc@au1.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Howells <dhowells@redhat.com> Cc: James Morris <jmorris@namei.org> Cc: <linux-man@vger.kernel.org> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* vfs: add generic_file_llseek_sizeAndi Kleen2011-10-281-9/+28
| | | | | | | | | | | Add a generic_file_llseek variant to the VFS that allows passing in the maximum file size of the file system, instead of always using maxbytes from the superblock. This can be used to eliminate some cut'n'paste seek code in ext4. Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
* vfs: do (nearly) lockless generic_file_llseekAndi Kleen2011-10-281-44/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The i_mutex lock use of generic _file_llseek hurts. Independent processes accessing the same file synchronize over a single lock, even though they have no need for synchronization at all. Under high utilization this can cause llseek to scale very poorly on larger systems. This patch does some rethinking of the llseek locking model: First the 64bit f_pos is not necessarily atomic without locks on 32bit systems. This can already cause races with read() today. This was discussed on linux-kernel in the past and deemed acceptable. The patch does not change that. Let's look at the different seek variants: SEEK_SET: Doesn't really need any locking. If there's a race one writer wins, the other loses. For 32bit the non atomic update races against read() stay the same. Without a lock they can also happen against write() now. The read() race was deemed acceptable in past discussions, and I think if it's ok for read it's ok for write too. => Don't need a lock. SEEK_END: This behaves like SEEK_SET plus it reads the maximum size too. Reading the maximum size would have the 32bit atomic problem. But luckily we already have a way to read the maximum size without locking (i_size_read), so we can just use that instead. Without i_mutex there is no synchronization with write() anymore, however since the write() update is atomic on 64bit it just behaves like another racy SEEK_SET. On non atomic 32bit it's the same as SEEK_SET. => Don't need a lock, but need to use i_size_read() SEEK_CUR: This has a read-modify-write race window on the same file. One could argue that any application doing unsynchronized seeks on the same file is already broken. But for the sake of not adding a regression here I'm using the file->f_lock to synchronize this. Using this lock is much better than the inode mutex because it doesn't synchronize between processes. => So still need a lock, but can use a f_lock. This patch implements this new scheme in generic_file_llseek. I dropped generic_file_llseek_unlocked and changed all callers. Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
* fs: add missing unlock in default_llseek()Dan Carpenter2011-07-261-4/+8
| | | | | | | | | A recent change in linux-next, 982d816581 "fs: add SEEK_HOLE and SEEK_DATA flags" added some direct returns on error, but it should have been a goto out. Signed-off-by: Dan Carpenter <error27@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs: add SEEK_HOLE and SEEK_DATA flagsJosef Bacik2011-07-211-3/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | This just gets us ready to support the SEEK_HOLE and SEEK_DATA flags. Turns out using fiemap in things like cp cause more problems than it solves, so lets try and give userspace an interface that doesn't suck. We need to match solaris here, and the definitions are *o* If /whence/ is SEEK_HOLE, the offset of the start of the next hole greater than or equal to the supplied offset is returned. The definition of a hole is provided near the end of the DESCRIPTION. *o* If /whence/ is SEEK_DATA, the file pointer is set to the start of the next non-hole file region greater than or equal to the supplied offset. So in the generic case the entire file is data and there is a virtual hole at the end. That means we will just return i_size for SEEK_HOLE and will return the same offset for SEEK_DATA. This is how Solaris does it so we have to do it the same way. Thanks, Signed-off-by: Josef Bacik <josef@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fix signedness mess in rw_verify_area() on 64bit architecturesAl Viro2011-01-131-16/+11
| | | | | | ... and clean the unsigned-f_pos code, while we are at it. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* BKL: remove extraneous #include <smp_lock.h>Arnd Bergmann2010-11-171-1/+0
| | | | | | | | | | The big kernel lock has been removed from all these files at some point, leaving only the #include. Remove this too as a cleanup. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* readv/writev: do the same MAX_RW_COUNT truncation that read/write doesLinus Torvalds2010-10-291-29/+33
| | | | | | | | | | We used to protect against overflow, but rather than return an error, do what read/write does, namely to limit the total size to MAX_RW_COUNT. This is not only more consistent, but it also means that any broken low-level read/write routine that still keeps counts in 'int' can't break. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* vfs: introduce FMODE_UNSIGNED_OFFSET for allowing negative f_posKAMEZAWA Hiroyuki2010-10-261-4/+24
| | | | | | | | | | | | | | | | | | Now, rw_verify_area() checsk f_pos is negative or not. And if negative, returns -EINVAL. But, some special files as /dev/(k)mem and /proc/<pid>/mem etc.. has negative offsets. And we can't do any access via read/write to the file(device). So introduce FMODE_UNSIGNED_OFFSET to allow negative file offsets. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: make no_llseek the defaultArnd Bergmann2010-10-151-1/+0
| | | | | | | | | | | | | | | | | | | | All file operations now have an explicit .llseek operation pointer, so we can change the default action for future code. This makes changes the default from default_llseek to no_llseek, which always returns -ESPIPE if a user tries to seek on a file without a .llseek operation. The name of the default_llseek function remains unchanged, if anyone thinks we should change it, please speak up. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org
* vfs: don't use BKL in default_llseekArnd Bergmann2010-10-151-2/+2
| | | | | | | | | | | | | | There are currently 191 users of default_llseek. Nine of these are in device drivers that use the big kernel lock. None of these ever touch file->f_pos outside of llseek or file_pos_write. Consequently, we never rely on the BKL in the default_llseek function and can replace that with i_mutex, which is also used in generic_file_llseek. Signed-off-by: Arnd Bergmann <arnd@arndb.de>
* fsnotify: pass a file instead of an inode to open, read, and writeEric Paris2010-07-281-4/+4
| | | | | | | | | | fanotify, the upcoming notification system actually needs a struct path so it can do opens in the context of listeners, and it needs a file so it can get f_flags from the original process. Close was the only operation that already was passing a struct file to the notification hook. This patch passes a file for access, modify, and open as well as they are easily available to these hooks. Signed-off-by: Eric Paris <eparis@redhat.com>
* vfs: introduce noop_llseek()jan Blunck2010-05-271-0/+17
| | | | | | | | | | | | | | This is an implementation of ->llseek useable for the rare special case when userspace expects the seek to succeed but the (device) file is actually not able to perform the seek. In this case you use noop_llseek() instead of falling back to the default implementation of ->llseek. Signed-off-by: Jan Blunck <jblunck@suse.de> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-16 15:49:25 +0100