1/*
2 * mm/fadvise.c
3 *
4 * Copyright (C) 2002, Linus Torvalds
5 *
6 * 11Jan2003	Andrew Morton
7 *		Initial version.
8 */
9
10#include <linux/kernel.h>
11#include <linux/file.h>
12#include <linux/fs.h>
13#include <linux/mm.h>
14#include <linux/pagemap.h>
15#include <linux/backing-dev.h>
16#include <linux/pagevec.h>
17#include <linux/fadvise.h>
18#include <linux/writeback.h>
19#include <linux/syscalls.h>
20
21#include <asm/unistd.h>
22
23/*
24 * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
25 * deactivate the pages and clear PG_Referenced.
26 */
27SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice)
28{
29	struct file *file = fget(fd);
30	struct address_space *mapping;
31	struct backing_dev_info *bdi;
32	loff_t endbyte;			/* inclusive */
33	pgoff_t start_index;
34	pgoff_t end_index;
35	unsigned long nrpages;
36	int ret = 0;
37
38	if (!file)
39		return -EBADF;
40
41	if (S_ISFIFO(file->f_path.dentry->d_inode->i_mode)) {
42		ret = -ESPIPE;
43		goto out;
44	}
45
46	mapping = file->f_mapping;
47	if (!mapping || len < 0) {
48		ret = -EINVAL;
49		goto out;
50	}
51
52	if (mapping->a_ops->get_xip_mem) {
53		switch (advice) {
54		case POSIX_FADV_NORMAL:
55		case POSIX_FADV_RANDOM:
56		case POSIX_FADV_SEQUENTIAL:
57		case POSIX_FADV_WILLNEED:
58		case POSIX_FADV_NOREUSE:
59		case POSIX_FADV_DONTNEED:
60			/* no bad return value, but ignore advice */
61			break;
62		default:
63			ret = -EINVAL;
64		}
65		goto out;
66	}
67
68	/* Careful about overflows. Len == 0 means "as much as possible" */
69	endbyte = offset + len;
70	if (!len || endbyte < len)
71		endbyte = -1;
72	else
73		endbyte--;		/* inclusive */
74
75	bdi = mapping->backing_dev_info;
76
77	switch (advice) {
78	case POSIX_FADV_NORMAL:
79		file->f_ra.ra_pages = bdi->ra_pages;
80		spin_lock(&file->f_lock);
81		file->f_mode &= ~FMODE_RANDOM;
82		spin_unlock(&file->f_lock);
83		break;
84	case POSIX_FADV_RANDOM:
85		spin_lock(&file->f_lock);
86		file->f_mode |= FMODE_RANDOM;
87		spin_unlock(&file->f_lock);
88		break;
89	case POSIX_FADV_SEQUENTIAL:
90		file->f_ra.ra_pages = bdi->ra_pages * 2;
91		spin_lock(&file->f_lock);
92		file->f_mode &= ~FMODE_RANDOM;
93		spin_unlock(&file->f_lock);
94		break;
95	case POSIX_FADV_WILLNEED:
96		if (!mapping->a_ops->readpage) {
97			ret = -EINVAL;
98			break;
99		}
100
101		/* First and last PARTIAL page! */
102		start_index = offset >> PAGE_CACHE_SHIFT;
103		end_index = endbyte >> PAGE_CACHE_SHIFT;
104
105		/* Careful about overflow on the "+1" */
106		nrpages = end_index - start_index + 1;
107		if (!nrpages)
108			nrpages = ~0UL;
109
110		ret = force_page_cache_readahead(mapping, file,
111				start_index,
112				nrpages);
113		if (ret > 0)
114			ret = 0;
115		break;
116	case POSIX_FADV_NOREUSE:
117		break;
118	case POSIX_FADV_DONTNEED:
119		if (!bdi_write_congested(mapping->backing_dev_info))
120			filemap_flush(mapping);
121
122		/* First and last FULL page! */
123		start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
124		end_index = (endbyte >> PAGE_CACHE_SHIFT);
125
126		if (end_index >= start_index)
127			invalidate_mapping_pages(mapping, start_index,
128						end_index);
129		break;
130	default:
131		ret = -EINVAL;
132	}
133out:
134	fput(file);
135	return ret;
136}
137#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
138asmlinkage long SyS_fadvise64_64(long fd, loff_t offset, loff_t len, long advice)
139{
140	return SYSC_fadvise64_64((int) fd, offset, len, (int) advice);
141}
142SYSCALL_ALIAS(sys_fadvise64_64, SyS_fadvise64_64);
143#endif
144
145#ifdef __ARCH_WANT_SYS_FADVISE64
146
147SYSCALL_DEFINE(fadvise64)(int fd, loff_t offset, size_t len, int advice)
148{
149	return sys_fadvise64_64(fd, offset, len, advice);
150}
151#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
152asmlinkage long SyS_fadvise64(long fd, loff_t offset, long len, long advice)
153{
154	return SYSC_fadvise64((int) fd, offset, (size_t)len, (int)advice);
155}
156SYSCALL_ALIAS(sys_fadvise64, SyS_fadvise64);
157#endif
158
159#endif
160