xref: /openbmc/linux/mm/fadvise.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  * mm/fadvise.c
3  *
4  * Copyright (C) 2002, Linus Torvalds
5  *
6  * 11Jan2003	akpm@digeo.com
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  */
27 asmlinkage long sys_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_page)
53 		/* no bad return value, but ignore advice */
54 		goto out;
55 
56 	/* Careful about overflows. Len == 0 means "as much as possible" */
57 	endbyte = offset + len;
58 	if (!len || endbyte < len)
59 		endbyte = -1;
60 	else
61 		endbyte--;		/* inclusive */
62 
63 	bdi = mapping->backing_dev_info;
64 
65 	switch (advice) {
66 	case POSIX_FADV_NORMAL:
67 		file->f_ra.ra_pages = bdi->ra_pages;
68 		break;
69 	case POSIX_FADV_RANDOM:
70 		file->f_ra.ra_pages = 0;
71 		break;
72 	case POSIX_FADV_SEQUENTIAL:
73 		file->f_ra.ra_pages = bdi->ra_pages * 2;
74 		break;
75 	case POSIX_FADV_WILLNEED:
76 		if (!mapping->a_ops->readpage) {
77 			ret = -EINVAL;
78 			break;
79 		}
80 
81 		/* First and last PARTIAL page! */
82 		start_index = offset >> PAGE_CACHE_SHIFT;
83 		end_index = endbyte >> PAGE_CACHE_SHIFT;
84 
85 		/* Careful about overflow on the "+1" */
86 		nrpages = end_index - start_index + 1;
87 		if (!nrpages)
88 			nrpages = ~0UL;
89 
90 		ret = force_page_cache_readahead(mapping, file,
91 				start_index,
92 				max_sane_readahead(nrpages));
93 		if (ret > 0)
94 			ret = 0;
95 		break;
96 	case POSIX_FADV_NOREUSE:
97 		break;
98 	case POSIX_FADV_DONTNEED:
99 		if (!bdi_write_congested(mapping->backing_dev_info))
100 			filemap_flush(mapping);
101 
102 		/* First and last FULL page! */
103 		start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
104 		end_index = (endbyte >> PAGE_CACHE_SHIFT);
105 
106 		if (end_index >= start_index)
107 			invalidate_mapping_pages(mapping, start_index,
108 						end_index);
109 		break;
110 	default:
111 		ret = -EINVAL;
112 	}
113 out:
114 	fput(file);
115 	return ret;
116 }
117 
118 #ifdef __ARCH_WANT_SYS_FADVISE64
119 
120 asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice)
121 {
122 	return sys_fadvise64_64(fd, offset, len, advice);
123 }
124 
125 #endif
126