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tag: v3.6-rc6
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/*
* mm/fadvise.c
*
* Copyright (C) 2002, Linus Torvalds
*
* 11Jan2003 Andrew Morton
* Initial version.
*/

#include <linux/kernel.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
#include <linux/fadvise.h>
#include <linux/writeback.h>
#include <linux/syscalls.h>

#include <asm/unistd.h>

/*
* POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
* deactivate the pages and clear PG_Referenced.
*/
SYSCALL_DEFINE(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_mem) {
switch (advice) {
case POSIX_FADV_NORMAL:
case POSIX_FADV_RANDOM:
case POSIX_FADV_SEQUENTIAL:
case POSIX_FADV_WILLNEED:
case POSIX_FADV_NOREUSE:
case POSIX_FADV_DONTNEED:
/* no bad return value, but ignore advice */
break;
default:
ret = -EINVAL;
}
goto out;
}

/* Careful about overflows. Len == 0 means "as much as possible" */
endbyte = offset + len;
if (!len || endbyte < len)
endbyte = -1;
else
endbyte--; /* inclusive */

bdi = mapping->backing_dev_info;

switch (advice) {
case POSIX_FADV_NORMAL:
file->f_ra.ra_pages = bdi->ra_pages;
spin_lock(&file->f_lock);
file->f_mode &= ~FMODE_RANDOM;
spin_unlock(&file->f_lock);
break;
case POSIX_FADV_RANDOM:
spin_lock(&file->f_lock);
file->f_mode |= FMODE_RANDOM;
spin_unlock(&file->f_lock);
break;
case POSIX_FADV_SEQUENTIAL:
file->f_ra.ra_pages = bdi->ra_pages * 2;
spin_lock(&file->f_lock);
file->f_mode &= ~FMODE_RANDOM;
spin_unlock(&file->f_lock);
break;
case POSIX_FADV_WILLNEED:
/* First and last PARTIAL page! */
start_index = offset >> PAGE_CACHE_SHIFT;
end_index = endbyte >> PAGE_CACHE_SHIFT;

/* Careful about overflow on the "+1" */
nrpages = end_index - start_index + 1;
if (!nrpages)
nrpages = ~0UL;

/*
* Ignore return value because fadvise() shall return
* success even if filesystem can't retrieve a hint,
*/
force_page_cache_readahead(mapping, file, start_index,
nrpages);
break;
case POSIX_FADV_NOREUSE:
break;
case POSIX_FADV_DONTNEED:
if (!bdi_write_congested(mapping->backing_dev_info))
__filemap_fdatawrite_range(mapping, offset, endbyte,
WB_SYNC_NONE);

/* First and last FULL page! */
start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
end_index = (endbyte >> PAGE_CACHE_SHIFT);

if (end_index >= start_index)
invalidate_mapping_pages(mapping, start_index,
end_index);
break;
default:
ret = -EINVAL;
}
out:
fput(file);
return ret;
}
#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
asmlinkage long SyS_fadvise64_64(long fd, loff_t offset, loff_t len, long advice)
{
return SYSC_fadvise64_64((int) fd, offset, len, (int) advice);
}
SYSCALL_ALIAS(sys_fadvise64_64, SyS_fadvise64_64);
#endif

#ifdef __ARCH_WANT_SYS_FADVISE64

SYSCALL_DEFINE(fadvise64)(int fd, loff_t offset, size_t len, int advice)
{
return sys_fadvise64_64(fd, offset, len, advice);
}
#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
asmlinkage long SyS_fadvise64(long fd, loff_t offset, long len, long advice)
{
return SYSC_fadvise64((int) fd, offset, (size_t)len, (int)advice);
}
SYSCALL_ALIAS(sys_fadvise64, SyS_fadvise64);
#endif

#endif
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