aha/include/linux/falloc.h

#ifndef _FALLOC_H_
#define _FALLOC_H_

#define FALLOC_FL_KEEP_SIZE	0x01 /* default is extend size */

#ifdef __KERNEL__

/*
 * Space reservation ioctls and argument structure
 * are designed to be compatible with the legacy XFS ioctls.
 */
struct space_resv {
	__s16		l_type;
	__s16		l_whence;
	__s64		l_start;
	__s64		l_len;		/* len == 0 means until end of file */
	__s32		l_sysid;
	__u32		l_pid;
	__s32		l_pad[4];	/* reserved area */
};

#define FS_IOC_RESVSP		_IOW('X', 40, struct space_resv)
#define FS_IOC_RESVSP64		_IOW('X', 42, struct space_resv)

#endif /* __KERNEL__ */

#endif /* _FALLOC_H_ */
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> 2007-07-18 01:42:44 +00:00			`#ifndef _FALLOC_H_`
			`#define _FALLOC_H_`

			`#define FALLOC_FL_KEEP_SIZE 0x01 /* default is extend size */`

fs: Add new pre-allocation ioctls to vfs for compatibility with legacy xfs ioctls This patch adds ioctls to vfs for compatibility with legacy XFS pre-allocation ioctls (XFS_IOC_RESVP). The implementation effectively invokes sys_fallocate for the new ioctls. Also handles the compat_ioctl case. Note: These legacy ioctls are also implemented by OCFS2. [AV: folded fixes from hch] Signed-off-by: Ankit Jain <me@ankitjain.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 2009-06-19 18:28:07 +00:00			`#ifdef __KERNEL__`

			`/*`
			`* Space reservation ioctls and argument structure`
			`* are designed to be compatible with the legacy XFS ioctls.`
			`*/`
			`struct space_resv {`
			`__s16 l_type;`
			`__s16 l_whence;`
			`__s64 l_start;`
			`__s64 l_len; /* len == 0 means until end of file */`
			`__s32 l_sysid;`
			`__u32 l_pid;`
			`__s32 l_pad[4]; /* reserved area */`
			`};`

			`#define FS_IOC_RESVSP _IOW('X', 40, struct space_resv)`
			`#define FS_IOC_RESVSP64 _IOW('X', 42, struct space_resv)`

			`#endif /* __KERNEL__ */`

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> 2007-07-18 01:42:44 +00:00			`#endif /* _FALLOC_H_ */`