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https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
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f79e2abb9b
Remove the recently-added LINUX_FADV_ASYNC_WRITE and LINUX_FADV_WRITE_WAIT fadvise() additions, do it in a new sys_sync_file_range() syscall instead. Reasons: - It's more flexible. Things which would require two or three syscalls with fadvise() can be done in a single syscall. - Using fadvise() in this manner is something not covered by POSIX. The patch wires up the syscall for x86. The sycall is implemented in the new fs/sync.c. The intention is that we can move sys_fsync(), sys_fdatasync() and perhaps sys_sync() into there later. Documentation for the syscall is in fs/sync.c. A test app (sync_file_range.c) is in http://www.zip.com.au/~akpm/linux/patches/stuff/ext3-tools.tar.gz. The available-to-GPL-modules do_sync_file_range() is for knfsd: "A COMMIT can say NFS_DATA_SYNC or NFS_FILE_SYNC. I can skip the ->fsync call for NFS_DATA_SYNC which is hopefully the more common." Note: the `async' writeout mode SYNC_FILE_RANGE_WRITE will turn synchronous if the queue is congested. This is trivial to fix: add a new flag bit, set wbc->nonblocking. But I'm not sure that we want to expose implementation details down to that level. Note: it's notable that we can sync an fd which wasn't opened for writing. Same with fsync() and fdatasync()). Note: the code takes some care to handle attempts to sync file contents outside the 16TB offset on 32-bit machines. It makes such attempts appear to succeed, for best 32-bit/64-bit compatibility. Perhaps it should make such requests fail... Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Cc: Ulrich Drepper <drepper@redhat.com> Cc: Neil Brown <neilb@cse.unsw.edu.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
137 lines
3.1 KiB
C
137 lines
3.1 KiB
C
/*
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* mm/fadvise.c
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*
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* Copyright (C) 2002, Linus Torvalds
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*
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* 11Jan2003 akpm@digeo.com
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* Initial version.
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*/
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#include <linux/kernel.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/pagemap.h>
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#include <linux/backing-dev.h>
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#include <linux/pagevec.h>
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#include <linux/fadvise.h>
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#include <linux/writeback.h>
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#include <linux/syscalls.h>
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#include <asm/unistd.h>
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/*
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* POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
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* deactivate the pages and clear PG_Referenced.
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*
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* LINUX_FADV_ASYNC_WRITE: start async writeout of any dirty pages between file
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* offsets `offset' and `offset+len' inclusive. Any pages which are currently
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* under writeout are skipped, whether or not they are dirty.
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*
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* LINUX_FADV_WRITE_WAIT: wait upon writeout of any dirty pages between file
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* offsets `offset' and `offset+len'.
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*
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* By combining these two operations the application may do several things:
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*
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* LINUX_FADV_ASYNC_WRITE: push some or all of the dirty pages at the disk.
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*
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*/
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asmlinkage long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
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{
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struct file *file = fget(fd);
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struct address_space *mapping;
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struct backing_dev_info *bdi;
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loff_t endbyte; /* inclusive */
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pgoff_t start_index;
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pgoff_t end_index;
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unsigned long nrpages;
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int ret = 0;
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if (!file)
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return -EBADF;
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if (S_ISFIFO(file->f_dentry->d_inode->i_mode)) {
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ret = -ESPIPE;
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goto out;
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}
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mapping = file->f_mapping;
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if (!mapping || len < 0) {
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ret = -EINVAL;
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goto out;
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}
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if (mapping->a_ops->get_xip_page)
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/* no bad return value, but ignore advice */
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goto out;
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/* Careful about overflows. Len == 0 means "as much as possible" */
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endbyte = offset + len;
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if (!len || endbyte < len)
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endbyte = -1;
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else
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endbyte--; /* inclusive */
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bdi = mapping->backing_dev_info;
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switch (advice) {
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case POSIX_FADV_NORMAL:
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file->f_ra.ra_pages = bdi->ra_pages;
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break;
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case POSIX_FADV_RANDOM:
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file->f_ra.ra_pages = 0;
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break;
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case POSIX_FADV_SEQUENTIAL:
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file->f_ra.ra_pages = bdi->ra_pages * 2;
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break;
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case POSIX_FADV_WILLNEED:
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case POSIX_FADV_NOREUSE:
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if (!mapping->a_ops->readpage) {
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ret = -EINVAL;
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break;
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}
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/* First and last PARTIAL page! */
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start_index = offset >> PAGE_CACHE_SHIFT;
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end_index = endbyte >> PAGE_CACHE_SHIFT;
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/* Careful about overflow on the "+1" */
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nrpages = end_index - start_index + 1;
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if (!nrpages)
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nrpages = ~0UL;
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ret = force_page_cache_readahead(mapping, file,
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start_index,
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max_sane_readahead(nrpages));
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if (ret > 0)
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ret = 0;
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break;
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case POSIX_FADV_DONTNEED:
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if (!bdi_write_congested(mapping->backing_dev_info))
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filemap_flush(mapping);
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/* First and last FULL page! */
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start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
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end_index = (endbyte >> PAGE_CACHE_SHIFT);
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if (end_index >= start_index)
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invalidate_mapping_pages(mapping, start_index,
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end_index);
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break;
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default:
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ret = -EINVAL;
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}
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out:
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fput(file);
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return ret;
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}
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#ifdef __ARCH_WANT_SYS_FADVISE64
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asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice)
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{
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return sys_fadvise64_64(fd, offset, len, advice);
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}
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#endif
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