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Diffstat (limited to '')
| -rw-r--r-- | mm/fadvise.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/mm/fadvise.c b/mm/fadvise.c new file mode 100644 index 000000000..467bcd032 --- /dev/null +++ b/mm/fadvise.c @@ -0,0 +1,220 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * mm/fadvise.c + * + * Copyright (C) 2002, Linus Torvalds + * + * 11Jan2003 Andrew Morton + * Initial version. + */ + +#include <linux/kernel.h> +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/mm.h> +#include <linux/pagemap.h> +#include <linux/backing-dev.h> +#include <linux/pagevec.h> +#include <linux/fadvise.h> +#include <linux/writeback.h> +#include <linux/syscalls.h> +#include <linux/swap.h> + +#include <asm/unistd.h> + +/* + * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could + * deactivate the pages and clear PG_Referenced. + */ + +static int generic_fadvise(struct file *file, loff_t offset, loff_t len, + int advice) +{ + struct inode *inode; + struct address_space *mapping; + struct backing_dev_info *bdi; + loff_t endbyte; /* inclusive */ + pgoff_t start_index; + pgoff_t end_index; + unsigned long nrpages; + + inode = file_inode(file); + if (S_ISFIFO(inode->i_mode)) + return -ESPIPE; + + mapping = file->f_mapping; + if (!mapping || len < 0) + return -EINVAL; + + bdi = inode_to_bdi(mapping->host); + + if (IS_DAX(inode) || (bdi == &noop_backing_dev_info)) { + switch (advice) { + case POSIX_FADV_NORMAL: + case POSIX_FADV_RANDOM: + case POSIX_FADV_SEQUENTIAL: + case POSIX_FADV_WILLNEED: + case POSIX_FADV_NOREUSE: + case POSIX_FADV_DONTNEED: + /* no bad return value, but ignore advice */ + break; + default: + return -EINVAL; + } + return 0; + } + + /* + * Careful about overflows. Len == 0 means "as much as possible". Use + * unsigned math because signed overflows are undefined and UBSan + * complains. + */ + endbyte = (u64)offset + (u64)len; + if (!len || endbyte < len) + endbyte = -1; + else + endbyte--; /* inclusive */ + + switch (advice) { + case POSIX_FADV_NORMAL: + file->f_ra.ra_pages = bdi->ra_pages; + spin_lock(&file->f_lock); + file->f_mode &= ~FMODE_RANDOM; + spin_unlock(&file->f_lock); + break; + case POSIX_FADV_RANDOM: + spin_lock(&file->f_lock); + file->f_mode |= FMODE_RANDOM; + spin_unlock(&file->f_lock); + break; + case POSIX_FADV_SEQUENTIAL: + file->f_ra.ra_pages = bdi->ra_pages * 2; + spin_lock(&file->f_lock); + file->f_mode &= ~FMODE_RANDOM; + spin_unlock(&file->f_lock); + break; + case POSIX_FADV_WILLNEED: + /* First and last PARTIAL page! */ + start_index = offset >> PAGE_SHIFT; + end_index = endbyte >> PAGE_SHIFT; + + /* Careful about overflow on the "+1" */ + nrpages = end_index - start_index + 1; + if (!nrpages) + nrpages = ~0UL; + + /* + * Ignore return value because fadvise() shall return + * success even if filesystem can't retrieve a hint, + */ + force_page_cache_readahead(mapping, file, start_index, nrpages); + break; + case POSIX_FADV_NOREUSE: + break; + case POSIX_FADV_DONTNEED: + if (!inode_write_congested(mapping->host)) + __filemap_fdatawrite_range(mapping, offset, endbyte, + WB_SYNC_NONE); + + /* + * First and last FULL page! Partial pages are deliberately + * preserved on the expectation that it is better to preserve + * needed memory than to discard unneeded memory. + */ + start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT; + end_index = (endbyte >> PAGE_SHIFT); + /* + * The page at end_index will be inclusively discarded according + * by invalidate_mapping_pages(), so subtracting 1 from + * end_index means we will skip the last page. But if endbyte + * is page aligned or is at the end of file, we should not skip + * that page - discarding the last page is safe enough. + */ + if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK && + endbyte != inode->i_size - 1) { + /* First page is tricky as 0 - 1 = -1, but pgoff_t + * is unsigned, so the end_index >= start_index + * check below would be true and we'll discard the whole + * file cache which is not what was asked. + */ + if (end_index == 0) + break; + + end_index--; + } + + if (end_index >= start_index) { + unsigned long count; + + /* + * It's common to FADV_DONTNEED right after + * the read or write that instantiates the + * pages, in which case there will be some + * sitting on the local LRU cache. Try to + * avoid the expensive remote drain and the + * second cache tree walk below by flushing + * them out right away. + */ + lru_add_drain(); + + count = invalidate_mapping_pages(mapping, + start_index, end_index); + + /* + * If fewer pages were invalidated than expected then + * it is possible that some of the pages were on + * a per-cpu pagevec for a remote CPU. Drain all + * pagevecs and try again. + */ + if (count < (end_index - start_index + 1)) { + lru_add_drain_all(); + invalidate_mapping_pages(mapping, start_index, + end_index); + } + } + break; + default: + return -EINVAL; + } + return 0; +} + +int vfs_fadvise(struct file *file, loff_t offset, loff_t len, int advice) +{ + if (file->f_op->fadvise) + return file->f_op->fadvise(file, offset, len, advice); + + return generic_fadvise(file, offset, len, advice); +} +EXPORT_SYMBOL(vfs_fadvise); + +#ifdef CONFIG_ADVISE_SYSCALLS + +int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice) +{ + struct fd f = fdget(fd); + int ret; + + if (!f.file) + return -EBADF; + + ret = vfs_fadvise(f.file, offset, len, advice); + + fdput(f); + return ret; +} + +SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice) +{ + return ksys_fadvise64_64(fd, offset, len, advice); +} + +#ifdef __ARCH_WANT_SYS_FADVISE64 + +SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice) +{ + return ksys_fadvise64_64(fd, offset, len, advice); +} + +#endif +#endif |