From 97ac73506c0ba93f30239bb57b4cfc5d73e68a62 Mon Sep 17 00:00:00 2001 From: Amit Arora Date: Tue, 17 Jul 2007 21:42:44 -0400 Subject: 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 --- arch/powerpc/kernel/sys_ppc32.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch/powerpc/kernel') diff --git a/arch/powerpc/kernel/sys_ppc32.c b/arch/powerpc/kernel/sys_ppc32.c index b42cbf1e2d7d..bd85b5fd08c8 100644 --- a/arch/powerpc/kernel/sys_ppc32.c +++ b/arch/powerpc/kernel/sys_ppc32.c @@ -773,6 +773,13 @@ asmlinkage int compat_sys_truncate64(const char __user * path, u32 reg4, return sys_truncate(path, (high << 32) | low); } +asmlinkage long compat_sys_fallocate(int fd, int mode, u32 offhi, u32 offlo, + u32 lenhi, u32 lenlo) +{ + return sys_fallocate(fd, mode, ((loff_t)offhi << 32) | offlo, + ((loff_t)lenhi << 32) | lenlo); +} + asmlinkage int compat_sys_ftruncate64(unsigned int fd, u32 reg4, unsigned long high, unsigned long low) { -- cgit v1.2.1