Fixed MTP to work with TWRP

mm/fadvise.c

@@ -0,0 +1,156 @@
+/*
+ * 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.
+ */
+SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
+{
+	struct fd f = fdget(fd);
+	struct address_space *mapping;
+	struct backing_dev_info *bdi;
+	loff_t endbyte;			/* inclusive */
+	pgoff_t start_index;
+	pgoff_t end_index;
+	unsigned long nrpages;
+	int ret = 0;
+
+	if (!f.file)
+		return -EBADF;
+
+	if (S_ISFIFO(file_inode(f.file)->i_mode)) {
+		ret = -ESPIPE;
+		goto out;
+	}
+
+	mapping = f.file->f_mapping;
+	if (!mapping || len < 0) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (mapping->a_ops->get_xip_mem) {
+		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:
+			ret = -EINVAL;
+		}
+		goto out;
+	}
+
+	/* Careful about overflows. Len == 0 means "as much as possible" */
+	endbyte = offset + len;
+	if (!len || endbyte < len)
+		endbyte = -1;
+	else
+		endbyte--;		/* inclusive */
+
+	bdi = mapping->backing_dev_info;
+
+	switch (advice) {
+	case POSIX_FADV_NORMAL:
+		f.file->f_ra.ra_pages = bdi->ra_pages;
+		spin_lock(&f.file->f_lock);
+		f.file->f_mode &= ~FMODE_RANDOM;
+		spin_unlock(&f.file->f_lock);
+		break;
+	case POSIX_FADV_RANDOM:
+		spin_lock(&f.file->f_lock);
+		f.file->f_mode |= FMODE_RANDOM;
+		spin_unlock(&f.file->f_lock);
+		break;
+	case POSIX_FADV_SEQUENTIAL:
+		f.file->f_ra.ra_pages = bdi->ra_pages * 2;
+		spin_lock(&f.file->f_lock);
+		f.file->f_mode &= ~FMODE_RANDOM;
+		spin_unlock(&f.file->f_lock);
+		break;
+	case POSIX_FADV_WILLNEED:
+		/* First and last PARTIAL page! */
+		start_index = offset >> PAGE_CACHE_SHIFT;
+		end_index = endbyte >> PAGE_CACHE_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, f.file, start_index,
+					   nrpages);
+		break;
+	case POSIX_FADV_NOREUSE:
+		break;
+	case POSIX_FADV_DONTNEED:
+		if (!bdi_write_congested(mapping->backing_dev_info))
+			__filemap_fdatawrite_range(mapping, offset, endbyte,
+						   WB_SYNC_NONE);
+
+		/* First and last FULL page! */
+		start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
+		end_index = (endbyte >> PAGE_CACHE_SHIFT);
+
+		if (end_index >= start_index) {
+			unsigned long 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:
+		ret = -EINVAL;
+	}
+out:
+	fdput(f);
+	return ret;
+}
+
+#ifdef __ARCH_WANT_SYS_FADVISE64
+
+SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
+{
+	return sys_fadvise64_64(fd, offset, len, advice);
+}
+
+#endif