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authorAmit Arora <aarora@in.ibm.com>2007-07-17 21:42:44 -0400
committerTheodore Ts'o <tytso@mit.edu>2007-07-17 21:42:44 -0400
commit97ac73506c0ba93f30239bb57b4cfc5d73e68a62 (patch)
tree4d02848d6c792a70b413deadcaffd7bf8c8d61de /include/asm-x86_64
parentcb32da0416b823b7f4b65e7e85d6cba16ca4d1e1 (diff)
downloadlinux-97ac73506c0ba93f30239bb57b4cfc5d73e68a62.tar.gz
sys_fallocate() implementation on i386, x86_64 and powerpc
fallocate() is a new system call being proposed here which will allow applications to preallocate space to any file(s) in a file system. Each file system implementation that wants to use this feature will need to support an inode operation called ->fallocate(). Applications can use this feature to avoid fragmentation to certain level and thus get faster access speed. With preallocation, applications also get a guarantee of space for particular file(s) - even if later the the system becomes full. Currently, glibc provides an interface called posix_fallocate() which can be used for similar cause. Though this has the advantage of working on all file systems, but it is quite slow (since it writes zeroes to each block that has to be preallocated). Without a doubt, file systems can do this more efficiently within the kernel, by implementing the proposed fallocate() system call. It is expected that posix_fallocate() will be modified to call this new system call first and incase the kernel/filesystem does not implement it, it should fall back to the current implementation of writing zeroes to the new blocks. ToDos: 1. Implementation on other architectures (other than i386, x86_64, and ppc). Patches for s390(x) and ia64 are already available from previous posts, but it was decided that they should be added later once fallocate is in the mainline. Hence not including those patches in this take. 2. Changes to glibc, a) to support fallocate() system call b) to make posix_fallocate() and posix_fallocate64() call fallocate() Signed-off-by: Amit Arora <aarora@in.ibm.com>
Diffstat (limited to 'include/asm-x86_64')
-rw-r--r--include/asm-x86_64/unistd.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/asm-x86_64/unistd.h b/include/asm-x86_64/unistd.h
index 8696f8ad401..fc4e73f5f1f 100644
--- a/include/asm-x86_64/unistd.h
+++ b/include/asm-x86_64/unistd.h
@@ -630,6 +630,8 @@ __SYSCALL(__NR_signalfd, sys_signalfd)
__SYSCALL(__NR_timerfd, sys_timerfd)
#define __NR_eventfd 284
__SYSCALL(__NR_eventfd, sys_eventfd)
+#define __NR_fallocate 285
+__SYSCALL(__NR_fallocate, sys_fallocate)
#ifndef __NO_STUBS
#define __ARCH_WANT_OLD_READDIR