Root/mm/fadvise.c

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

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