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![Jan Kara](/assets/img/avatar_default.png)
Filesystems will need to call this function from their fadvise handlers. CC: stable@vger.kernel.org Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
220 lines
5.4 KiB
C
220 lines
5.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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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 Andrew Morton
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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 <linux/swap.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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int generic_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
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{
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struct inode *inode;
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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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inode = file_inode(file);
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if (S_ISFIFO(inode->i_mode))
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return -ESPIPE;
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mapping = file->f_mapping;
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if (!mapping || len < 0)
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return -EINVAL;
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bdi = inode_to_bdi(mapping->host);
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if (IS_DAX(inode) || (bdi == &noop_backing_dev_info)) {
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switch (advice) {
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case POSIX_FADV_NORMAL:
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case POSIX_FADV_RANDOM:
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case POSIX_FADV_SEQUENTIAL:
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case POSIX_FADV_WILLNEED:
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case POSIX_FADV_NOREUSE:
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case POSIX_FADV_DONTNEED:
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/* no bad return value, but ignore advice */
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break;
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default:
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return -EINVAL;
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}
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return 0;
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}
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/*
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* Careful about overflows. Len == 0 means "as much as possible". Use
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* unsigned math because signed overflows are undefined and UBSan
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* complains.
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*/
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endbyte = (u64)offset + (u64)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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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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spin_lock(&file->f_lock);
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file->f_mode &= ~FMODE_RANDOM;
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spin_unlock(&file->f_lock);
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break;
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case POSIX_FADV_RANDOM:
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spin_lock(&file->f_lock);
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file->f_mode |= FMODE_RANDOM;
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spin_unlock(&file->f_lock);
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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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spin_lock(&file->f_lock);
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file->f_mode &= ~FMODE_RANDOM;
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spin_unlock(&file->f_lock);
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break;
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case POSIX_FADV_WILLNEED:
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/* First and last PARTIAL page! */
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start_index = offset >> PAGE_SHIFT;
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end_index = endbyte >> PAGE_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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/*
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* Ignore return value because fadvise() shall return
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* success even if filesystem can't retrieve a hint,
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*/
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force_page_cache_readahead(mapping, file, start_index, nrpages);
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break;
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case POSIX_FADV_NOREUSE:
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break;
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case POSIX_FADV_DONTNEED:
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if (!inode_write_congested(mapping->host))
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__filemap_fdatawrite_range(mapping, offset, endbyte,
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WB_SYNC_NONE);
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/*
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* First and last FULL page! Partial pages are deliberately
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* preserved on the expectation that it is better to preserve
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* needed memory than to discard unneeded memory.
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*/
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start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT;
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end_index = (endbyte >> PAGE_SHIFT);
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/*
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* The page at end_index will be inclusively discarded according
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* by invalidate_mapping_pages(), so subtracting 1 from
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* end_index means we will skip the last page. But if endbyte
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* is page aligned or is at the end of file, we should not skip
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* that page - discarding the last page is safe enough.
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*/
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if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK &&
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endbyte != inode->i_size - 1) {
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/* First page is tricky as 0 - 1 = -1, but pgoff_t
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* is unsigned, so the end_index >= start_index
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* check below would be true and we'll discard the whole
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* file cache which is not what was asked.
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*/
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if (end_index == 0)
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break;
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end_index--;
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}
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if (end_index >= start_index) {
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unsigned long count;
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/*
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* It's common to FADV_DONTNEED right after
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* the read or write that instantiates the
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* pages, in which case there will be some
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* sitting on the local LRU cache. Try to
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* avoid the expensive remote drain and the
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* second cache tree walk below by flushing
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* them out right away.
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*/
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lru_add_drain();
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count = invalidate_mapping_pages(mapping,
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start_index, end_index);
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/*
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* If fewer pages were invalidated than expected then
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* it is possible that some of the pages were on
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* a per-cpu pagevec for a remote CPU. Drain all
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* pagevecs and try again.
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*/
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if (count < (end_index - start_index + 1)) {
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lru_add_drain_all();
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invalidate_mapping_pages(mapping, start_index,
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end_index);
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}
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}
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break;
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default:
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return -EINVAL;
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}
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return 0;
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}
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EXPORT_SYMBOL(generic_fadvise);
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int vfs_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
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{
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if (file->f_op->fadvise)
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return file->f_op->fadvise(file, offset, len, advice);
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return generic_fadvise(file, offset, len, advice);
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}
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EXPORT_SYMBOL(vfs_fadvise);
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#ifdef CONFIG_ADVISE_SYSCALLS
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int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
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{
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struct fd f = fdget(fd);
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int ret;
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if (!f.file)
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return -EBADF;
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ret = vfs_fadvise(f.file, offset, len, advice);
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fdput(f);
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return ret;
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}
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SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
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{
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return ksys_fadvise64_64(fd, offset, len, advice);
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}
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#ifdef __ARCH_WANT_SYS_FADVISE64
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SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
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{
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return ksys_fadvise64_64(fd, offset, len, advice);
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}
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#endif
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#endif
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