4 * Copyright (C) 2002, Linus Torvalds
6 * 11Jan2003 Andrew Morton
10 #include <linux/kernel.h>
11 #include <linux/file.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>
22 #include <asm/unistd.h>
25 * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
26 * deactivate the pages and clear PG_Referenced.
28 SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
30 struct fd f = fdget(fd);
32 struct address_space *mapping;
33 struct backing_dev_info *bdi;
34 loff_t endbyte; /* inclusive */
37 unsigned long nrpages;
43 inode = file_inode(f.file);
44 if (S_ISFIFO(inode->i_mode)) {
49 mapping = f.file->f_mapping;
50 if (!mapping || len < 0) {
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 */
71 /* Careful about overflows. Len == 0 means "as much as possible" */
72 endbyte = offset + len;
73 if (!len || endbyte < len)
76 endbyte--; /* inclusive */
78 bdi = inode_to_bdi(mapping->host);
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);
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);
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);
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;
103 /* Careful about overflow on the "+1" */
104 nrpages = end_index - start_index + 1;
109 * Ignore return value because fadvise() shall return
110 * success even if filesystem can't retrieve a hint,
112 force_page_cache_readahead(mapping, f.file, start_index,
115 case POSIX_FADV_NOREUSE:
117 case POSIX_FADV_DONTNEED:
118 if (!bdi_write_congested(bdi))
119 __filemap_fdatawrite_range(mapping, offset, endbyte,
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.
127 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
128 end_index = (endbyte >> PAGE_CACHE_SHIFT);
130 if (end_index >= start_index) {
131 unsigned long count = invalidate_mapping_pages(mapping,
132 start_index, end_index);
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.
140 if (count < (end_index - start_index + 1)) {
142 invalidate_mapping_pages(mapping, start_index,
155 #ifdef __ARCH_WANT_SYS_FADVISE64
157 SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
159 return sys_fadvise64_64(fd, offset, len, advice);