mm cleanup: split out mincore() system call from filemap.c

mm/Makefile

@@ -14,6 +14,6 @@ export-objs := shmem.o filemap.o mempool.o page_alloc.o
 obj-y	 := memory.o mmap.o filemap.o mprotect.o mlock.o mremap.o \
 	    vmalloc.o slab.o bootmem.o swap.o vmscan.o page_io.o \
 	    page_alloc.o swap_state.o swapfile.o numa.o oom_kill.o \
-	    shmem.o highmem.o mempool.o msync.o
+	    shmem.o highmem.o mempool.o msync.o mincore.o
 
 include $(TOPDIR)/Rules.make

mm/filemap.c

@@ -2455,160 +2455,6 @@ asmlinkage long sys_madvise(unsigned long start, size_t len, int behavior)
 	return error;
 }
 
-/*
- * Later we can get more picky about what "in core" means precisely.
- * For now, simply check to see if the page is in the page cache,
- * and is up to date; i.e. that no page-in operation would be required
- * at this time if an application were to map and access this page.
- */
-static unsigned char mincore_page(struct vm_area_struct * vma,
-	unsigned long pgoff)
-{
-	unsigned char present = 0;
-	struct address_space * as = vma->vm_file->f_dentry->d_inode->i_mapping;
-	struct page * page, ** hash = page_hash(as, pgoff);
-
-	spin_lock(&pagecache_lock);
-	page = __find_page_nolock(as, pgoff, *hash);
-	if ((page) && (Page_Uptodate(page)))
-		present = 1;
-	spin_unlock(&pagecache_lock);
-
-	return present;
-}
-
-static long mincore_vma(struct vm_area_struct * vma,
-	unsigned long start, unsigned long end, unsigned char * vec)
-{
-	long error, i, remaining;
-	unsigned char * tmp;
-
-	error = -ENOMEM;
-	if (!vma->vm_file)
-		return error;
-
-	start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
-	if (end > vma->vm_end)
-		end = vma->vm_end;
-	end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
-
-	error = -EAGAIN;
-	tmp = (unsigned char *) __get_free_page(GFP_KERNEL);
-	if (!tmp)
-		return error;
-
-	/* (end - start) is # of pages, and also # of bytes in "vec */
-	remaining = (end - start),
-
-	error = 0;
-	for (i = 0; remaining > 0; remaining -= PAGE_SIZE, i++) {
-		int j = 0;
-		long thispiece = (remaining < PAGE_SIZE) ?
-						remaining : PAGE_SIZE;
-
-		while (j < thispiece)
-			tmp[j++] = mincore_page(vma, start++);
-
-		if (copy_to_user(vec + PAGE_SIZE * i, tmp, thispiece)) {
-			error = -EFAULT;
-			break;
-		}
-	}
-
-	free_page((unsigned long) tmp);
-	return error;
-}
-
-/*
- * The mincore(2) system call.
- *
- * mincore() returns the memory residency status of the pages in the
- * current process's address space specified by [addr, addr + len).
- * The status is returned in a vector of bytes.  The least significant
- * bit of each byte is 1 if the referenced page is in memory, otherwise
- * it is zero.
- *
- * Because the status of a page can change after mincore() checks it
- * but before it returns to the application, the returned vector may
- * contain stale information.  Only locked pages are guaranteed to
- * remain in memory.
- *
- * return values:
- *  zero    - success
- *  -EFAULT - vec points to an illegal address
- *  -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE,
- *		or len has a nonpositive value
- *  -ENOMEM - Addresses in the range [addr, addr + len] are
- *		invalid for the address space of this process, or
- *		specify one or more pages which are not currently
- *		mapped
- *  -EAGAIN - A kernel resource was temporarily unavailable.
- */
-asmlinkage long sys_mincore(unsigned long start, size_t len,
-	unsigned char * vec)
-{
-	int index = 0;
-	unsigned long end;
-	struct vm_area_struct * vma;
-	int unmapped_error = 0;
-	long error = -EINVAL;
-
-	down_read(&current->mm->mmap_sem);
-
-	if (start & ~PAGE_CACHE_MASK)
-		goto out;
-	len = (len + ~PAGE_CACHE_MASK) & PAGE_CACHE_MASK;
-	end = start + len;
-	if (end < start)
-		goto out;
-
-	error = 0;
-	if (end == start)
-		goto out;
-
-	/*
-	 * If the interval [start,end) covers some unmapped address
-	 * ranges, just ignore them, but return -ENOMEM at the end.
-	 */
-	vma = find_vma(current->mm, start);
-	for (;;) {
-		/* Still start < end. */
-		error = -ENOMEM;
-		if (!vma)
-			goto out;
-
-		/* Here start < vma->vm_end. */
-		if (start < vma->vm_start) {
-			unmapped_error = -ENOMEM;
-			start = vma->vm_start;
-		}
-
-		/* Here vma->vm_start <= start < vma->vm_end. */
-		if (end <= vma->vm_end) {
-			if (start < end) {
-				error = mincore_vma(vma, start, end,
-							&vec[index]);
-				if (error)
-					goto out;
-			}
-			error = unmapped_error;
-			goto out;
-		}
-
-		/* Here vma->vm_start <= start < vma->vm_end < end. */
-		error = mincore_vma(vma, start, vma->vm_end, &vec[index]);
-		if (error)
-			goto out;
-		index += (vma->vm_end - start) >> PAGE_CACHE_SHIFT;
-		start = vma->vm_end;
-		vma = vma->vm_next;
-	}
-
-out:
-	up_read(&current->mm->mmap_sem);
-	return error;
-}
-
 static inline
 struct page *__read_cache_page(struct address_space *mapping,
 				unsigned long index,

mm/mincore.c

+/*
+ *	linux/mm/mincore.c
+ *
+ * Copyright (C) 1994-1999  Linus Torvalds
+ */
+
+/*
+ * The mincore() system call.
+ */
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+
+/*
+ * Later we can get more picky about what "in core" means precisely.
+ * For now, simply check to see if the page is in the page cache,
+ * and is up to date; i.e. that no page-in operation would be required
+ * at this time if an application were to map and access this page.
+ */
+static unsigned char mincore_page(struct vm_area_struct * vma,
+	unsigned long pgoff)
+{
+	unsigned char present = 0;
+	struct address_space * as = vma->vm_file->f_dentry->d_inode->i_mapping;
+	struct page * page, ** hash = page_hash(as, pgoff);
+
+	page = __find_get_page(as, pgoff, hash);
+	if (page) {
+		present = Page_Uptodate(page);
+		page_cache_release(page);
+	}
+
+	return present;
+}
+
+static long mincore_vma(struct vm_area_struct * vma,
+	unsigned long start, unsigned long end, unsigned char * vec)
+{
+	long error, i, remaining;
+	unsigned char * tmp;
+
+	error = -ENOMEM;
+	if (!vma->vm_file)
+		return error;
+
+	start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+	if (end > vma->vm_end)
+		end = vma->vm_end;
+	end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+
+	error = -EAGAIN;
+	tmp = (unsigned char *) __get_free_page(GFP_KERNEL);
+	if (!tmp)
+		return error;
+
+	/* (end - start) is # of pages, and also # of bytes in "vec */
+	remaining = (end - start),
+
+	error = 0;
+	for (i = 0; remaining > 0; remaining -= PAGE_SIZE, i++) {
+		int j = 0;
+		long thispiece = (remaining < PAGE_SIZE) ?
+						remaining : PAGE_SIZE;
+
+		while (j < thispiece)
+			tmp[j++] = mincore_page(vma, start++);
+
+		if (copy_to_user(vec + PAGE_SIZE * i, tmp, thispiece)) {
+			error = -EFAULT;
+			break;
+		}
+	}
+
+	free_page((unsigned long) tmp);
+	return error;
+}
+
+/*
+ * The mincore(2) system call.
+ *
+ * mincore() returns the memory residency status of the pages in the
+ * current process's address space specified by [addr, addr + len).
+ * The status is returned in a vector of bytes.  The least significant
+ * bit of each byte is 1 if the referenced page is in memory, otherwise
+ * it is zero.
+ *
+ * Because the status of a page can change after mincore() checks it
+ * but before it returns to the application, the returned vector may
+ * contain stale information.  Only locked pages are guaranteed to
+ * remain in memory.
+ *
+ * return values:
+ *  zero    - success
+ *  -EFAULT - vec points to an illegal address
+ *  -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE,
+ *		or len has a nonpositive value
+ *  -ENOMEM - Addresses in the range [addr, addr + len] are
+ *		invalid for the address space of this process, or
+ *		specify one or more pages which are not currently
+ *		mapped
+ *  -EAGAIN - A kernel resource was temporarily unavailable.
+ */
+asmlinkage long sys_mincore(unsigned long start, size_t len,
+	unsigned char * vec)
+{
+	int index = 0;
+	unsigned long end;
+	struct vm_area_struct * vma;
+	int unmapped_error = 0;
+	long error = -EINVAL;
+
+	down_read(&current->mm->mmap_sem);
+
+	if (start & ~PAGE_CACHE_MASK)
+		goto out;
+	len = (len + ~PAGE_CACHE_MASK) & PAGE_CACHE_MASK;
+	end = start + len;
+	if (end < start)
+		goto out;
+
+	error = -EFAULT;
+	if (!access_ok(VERIFY_WRITE, (unsigned long) vec, len >> PAGE_SHIFT))
+		goto out;
+
+	error = 0;
+	if (end == start)
+		goto out;
+
+	/*
+	 * If the interval [start,end) covers some unmapped address
+	 * ranges, just ignore them, but return -ENOMEM at the end.
+	 */
+	vma = find_vma(current->mm, start);
+	for (;;) {
+		/* Still start < end. */
+		error = -ENOMEM;
+		if (!vma)
+			goto out;
+
+		/* Here start < vma->vm_end. */
+		if (start < vma->vm_start) {
+			unmapped_error = -ENOMEM;
+			start = vma->vm_start;
+		}
+
+		/* Here vma->vm_start <= start < vma->vm_end. */
+		if (end <= vma->vm_end) {
+			if (start < end) {
+				error = mincore_vma(vma, start, end,
+							&vec[index]);
+				if (error)
+					goto out;
+			}
+			error = unmapped_error;
+			goto out;
+		}
+
+		/* Here vma->vm_start <= start < vma->vm_end < end. */
+		error = mincore_vma(vma, start, vma->vm_end, &vec[index]);
+		if (error)
+			goto out;
+		index += (vma->vm_end - start) >> PAGE_CACHE_SHIFT;
+		start = vma->vm_end;
+		vma = vma->vm_next;
+	}
+
+out:
+	up_read(&current->mm->mmap_sem);
+	return error;
+}