diff options
Diffstat (limited to 'mm/readahead.c')
| -rw-r--r-- | mm/readahead.c | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/mm/readahead.c b/mm/readahead.c index cbcbb02f3e28..ea8f8fa21649 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -17,6 +17,8 @@ #include <linux/task_io_accounting_ops.h> #include <linux/pagevec.h> #include <linux/pagemap.h> +#include <linux/syscalls.h> +#include <linux/file.h> /* * Initialise a struct file's readahead state. Assumes that the caller has @@ -562,3 +564,41 @@ page_cache_async_readahead(struct address_space *mapping, ondemand_readahead(mapping, ra, filp, true, offset, req_size); } EXPORT_SYMBOL_GPL(page_cache_async_readahead); + +static ssize_t +do_readahead(struct address_space *mapping, struct file *filp, + pgoff_t index, unsigned long nr) +{ + if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) + return -EINVAL; + + force_page_cache_readahead(mapping, filp, index, nr); + return 0; +} + +SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count) +{ + ssize_t ret; + struct file *file; + + ret = -EBADF; + file = fget(fd); + if (file) { + if (file->f_mode & FMODE_READ) { + struct address_space *mapping = file->f_mapping; + pgoff_t start = offset >> PAGE_CACHE_SHIFT; + pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT; + unsigned long len = end - start + 1; + ret = do_readahead(mapping, file, start, len); + } + fput(file); + } + return ret; +} +#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS +asmlinkage long SyS_readahead(long fd, loff_t offset, long count) +{ + return SYSC_readahead((int) fd, offset, (size_t) count); +} +SYSCALL_ALIAS(sys_readahead, SyS_readahead); +#endif |