Add "maxfilesize" mount option for tmpfs to allow specifying the

maximum file size limit. Default is UINT64_MAX when the option is
not specified. It was useless to set the limit to the total amount of
memory and swap in the system.

Use tmpfs_mem_info() rather than get_swpgtotal() in tmpfs_mount() to
check if there is enough memory available.

Remove now unused get_swpgtotal().

Reviewed by:	Gleb Kurtsou
Approved by:	trasz (mentor)

share/man/man5/tmpfs.5

@@ -70,6 +70,8 @@ permissions in octal format.
 maximum number of inodes.
 .It Cm size
 maximum size (in bytes) for the file system.
+.It Cm maxfilesize
+maximum file size (in bytes).
 .El
 .Sh EXAMPLES
 To mount a

sys/fs/tmpfs/tmpfs_vfsops.c

@@ -77,62 +77,12 @@ static int	tmpfs_statfs(struct mount *, struct statfs *);
 /* --------------------------------------------------------------------- */
 
 static const char *tmpfs_opts[] = {
-	"from", "size", "inodes", "uid", "gid", "mode", "export",
+	"from", "size", "maxfilesize", "inodes", "uid", "gid", "mode", "export",
 	NULL
 };
 
 /* --------------------------------------------------------------------- */
 
-#define SWI_MAXMIB	3
-
-static u_int
-get_swpgtotal(void)
-{
-	struct xswdev xsd;
-	char *sname = "vm.swap_info";
-	int soid[SWI_MAXMIB], oid[2];
-	u_int unswdev, total, dmmax, nswapdev;
-	size_t mibi, len;
-
-	total = 0;
-
-	len = sizeof(dmmax);
-	if (kernel_sysctlbyname(curthread, "vm.dmmax", &dmmax, &len,
-				NULL, 0, NULL, 0) != 0)
-		return total;
-
-	len = sizeof(nswapdev);
-	if (kernel_sysctlbyname(curthread, "vm.nswapdev",
-				&nswapdev, &len,
-				NULL, 0, NULL, 0) != 0)
-		return total;
-
-	mibi = (SWI_MAXMIB - 1) * sizeof(int);
-	oid[0] = 0;
-	oid[1] = 3;
-
-	if (kernel_sysctl(curthread, oid, 2,
-			soid, &mibi, (void *)sname, strlen(sname),
-			NULL, 0) != 0)
-		return total;
-
-	mibi = (SWI_MAXMIB - 1);
-	for (unswdev = 0; unswdev < nswapdev; ++unswdev) {
-		soid[mibi] = unswdev;
-		len = sizeof(struct xswdev);
-		if (kernel_sysctl(curthread,
-				soid, mibi + 1, &xsd, &len, NULL, 0,
-				NULL, 0) != 0)
-			return total;
-		if (len == sizeof(struct xswdev))
-			total += (xsd.xsw_nblks - dmmax);
-	}
-
-	/* Not Reached */
-	return total;
-}
-
-/* --------------------------------------------------------------------- */
 static int
 tmpfs_node_ctor(void *mem, int size, void *arg, int flags)
 {
@@ -181,12 +131,12 @@ tmpfs_mount(struct mount *mp)
 {
 	struct tmpfs_mount *tmp;
 	struct tmpfs_node *root;
-	size_t pages, mem_size;
+	size_t pages;
 	uint32_t nodes;
 	int error;
 	/* Size counters. */
 	u_int nodes_max;
-	u_quad_t size_max;
+	u_quad_t size_max, maxfilesize;
 
 	/* Root node attributes. */
 	uid_t root_uid;
@@ -227,12 +177,13 @@ tmpfs_mount(struct mount *mp)
 		nodes_max = 0;
 	if (vfs_scanopt(mp->mnt_optnew, "size", "%qu", &size_max) != 1)
 		size_max = 0;
+	if (vfs_scanopt(mp->mnt_optnew, "maxfilesize", "%qu",
+	    &maxfilesize) != 1)
+		maxfilesize = 0;
 
 	/* Do not allow mounts if we do not have enough memory to preserve
 	 * the minimum reserved pages. */
-	mem_size = cnt.v_free_count + cnt.v_inactive_count + get_swpgtotal();
+	if (tmpfs_mem_info() < TMPFS_PAGES_RESERVED)
-	mem_size -= mem_size > cnt.v_wire_count ? cnt.v_wire_count : mem_size;
-	if (mem_size < TMPFS_PAGES_RESERVED)
 		return ENOSPC;
 
 	/* Get the maximum number of memory pages this file system is
@@ -261,7 +212,7 @@ tmpfs_mount(struct mount *mp)
 	mtx_init(&tmp->allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF);
 	tmp->tm_nodes_max = nodes;
 	tmp->tm_nodes_inuse = 0;
-	tmp->tm_maxfilesize = (u_int64_t)(cnt.v_page_count + get_swpgtotal()) * PAGE_SIZE;
+	tmp->tm_maxfilesize = maxfilesize > 0 ? maxfilesize : UINT64_MAX;
 	LIST_INIT(&tmp->tm_nodes_used);
 
 	tmp->tm_pages_max = pages;