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[kvmfornfv.git] / kernel / 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 #include <linux/swap.h>
21
22 #include <asm/unistd.h>
23
24 /*
25  * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
26  * deactivate the pages and clear PG_Referenced.
27  */
28 SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
29 {
30         struct fd f = fdget(fd);
31         struct inode *inode;
32         struct address_space *mapping;
33         struct backing_dev_info *bdi;
34         loff_t endbyte;                 /* inclusive */
35         pgoff_t start_index;
36         pgoff_t end_index;
37         unsigned long nrpages;
38         int ret = 0;
39
40         if (!f.file)
41                 return -EBADF;
42
43         inode = file_inode(f.file);
44         if (S_ISFIFO(inode->i_mode)) {
45                 ret = -ESPIPE;
46                 goto out;
47         }
48
49         mapping = f.file->f_mapping;
50         if (!mapping || len < 0) {
51                 ret = -EINVAL;
52                 goto out;
53         }
54
55         if (IS_DAX(inode)) {
56                 switch (advice) {
57                 case POSIX_FADV_NORMAL:
58                 case POSIX_FADV_RANDOM:
59                 case POSIX_FADV_SEQUENTIAL:
60                 case POSIX_FADV_WILLNEED:
61                 case POSIX_FADV_NOREUSE:
62                 case POSIX_FADV_DONTNEED:
63                         /* no bad return value, but ignore advice */
64                         break;
65                 default:
66                         ret = -EINVAL;
67                 }
68                 goto out;
69         }
70
71         /* Careful about overflows. Len == 0 means "as much as possible" */
72         endbyte = offset + len;
73         if (!len || endbyte < len)
74                 endbyte = -1;
75         else
76                 endbyte--;              /* inclusive */
77
78         bdi = inode_to_bdi(mapping->host);
79
80         switch (advice) {
81         case POSIX_FADV_NORMAL:
82                 f.file->f_ra.ra_pages = bdi->ra_pages;
83                 spin_lock(&f.file->f_lock);
84                 f.file->f_mode &= ~FMODE_RANDOM;
85                 spin_unlock(&f.file->f_lock);
86                 break;
87         case POSIX_FADV_RANDOM:
88                 spin_lock(&f.file->f_lock);
89                 f.file->f_mode |= FMODE_RANDOM;
90                 spin_unlock(&f.file->f_lock);
91                 break;
92         case POSIX_FADV_SEQUENTIAL:
93                 f.file->f_ra.ra_pages = bdi->ra_pages * 2;
94                 spin_lock(&f.file->f_lock);
95                 f.file->f_mode &= ~FMODE_RANDOM;
96                 spin_unlock(&f.file->f_lock);
97                 break;
98         case POSIX_FADV_WILLNEED:
99                 /* First and last PARTIAL page! */
100                 start_index = offset >> PAGE_CACHE_SHIFT;
101                 end_index = endbyte >> PAGE_CACHE_SHIFT;
102
103                 /* Careful about overflow on the "+1" */
104                 nrpages = end_index - start_index + 1;
105                 if (!nrpages)
106                         nrpages = ~0UL;
107
108                 /*
109                  * Ignore return value because fadvise() shall return
110                  * success even if filesystem can't retrieve a hint,
111                  */
112                 force_page_cache_readahead(mapping, f.file, start_index,
113                                            nrpages);
114                 break;
115         case POSIX_FADV_NOREUSE:
116                 break;
117         case POSIX_FADV_DONTNEED:
118                 if (!bdi_write_congested(bdi))
119                         __filemap_fdatawrite_range(mapping, offset, endbyte,
120                                                    WB_SYNC_NONE);
121
122                 /*
123                  * First and last FULL page! Partial pages are deliberately
124                  * preserved on the expectation that it is better to preserve
125                  * needed memory than to discard unneeded memory.
126                  */
127                 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
128                 end_index = (endbyte >> PAGE_CACHE_SHIFT);
129
130                 if (end_index >= start_index) {
131                         unsigned long count = invalidate_mapping_pages(mapping,
132                                                 start_index, end_index);
133
134                         /*
135                          * If fewer pages were invalidated than expected then
136                          * it is possible that some of the pages were on
137                          * a per-cpu pagevec for a remote CPU. Drain all
138                          * pagevecs and try again.
139                          */
140                         if (count < (end_index - start_index + 1)) {
141                                 lru_add_drain_all();
142                                 invalidate_mapping_pages(mapping, start_index,
143                                                 end_index);
144                         }
145                 }
146                 break;
147         default:
148                 ret = -EINVAL;
149         }
150 out:
151         fdput(f);
152         return ret;
153 }
154
155 #ifdef __ARCH_WANT_SYS_FADVISE64
156
157 SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
158 {
159         return sys_fadvise64_64(fd, offset, len, advice);
160 }
161
162 #endif