diff --git a/bin/df/df.1 b/bin/df/df.1
--- a/bin/df/df.1
+++ b/bin/df/df.1
@@ -29,7 +29,7 @@
 .\"     @(#)df.1	8.3 (Berkeley) 5/8/95
 .\" $FreeBSD$
 .\"
-.Dd March 11, 2022
+.Dd March 29, 2023
 .Dt DF 1
 .Os
 .Sh NAME
@@ -246,6 +246,17 @@
 Filesystem     Size    Used   Avail Capacity  Mounted on
 /dev/ada1p2    213G    152G     44G    78%    /
 .Ed
+.Sh NOTES
+For non-Unix file systems, the reported values of used and free inodes
+may have a different meaning than that of used and available files and
+directories.
+An example is msdosfs, which in the case of FAT12 or FAT16 file systems
+reports the number of available and free root directory entries instead
+of inodes
+.Po
+where 1 to 21 such directory entries are required to store
+each file or directory name or disk label
+.Pc .
 .Sh SEE ALSO
 .Xr lsvfs 1 ,
 .Xr quota 1 ,
diff --git a/lib/libc/sys/statfs.2 b/lib/libc/sys/statfs.2
--- a/lib/libc/sys/statfs.2
+++ b/lib/libc/sys/statfs.2
@@ -28,7 +28,7 @@
 .\"	@(#)statfs.2	8.5 (Berkeley) 5/24/95
 .\" $FreeBSD$
 .\"
-.Dd March 30, 2020
+.Dd March 29, 2023
 .Dt STATFS 2
 .Os
 .Sh NAME
@@ -230,6 +230,22 @@
 .It Bq Er EINTEGRITY
 Corrupted data was detected while reading from the file system.
 .El
+.Sh NOTES
+The fields in the
+.Vt statfs
+structure have been defined to provide the parameters relevant for
+traditional
+.Tm UNIX
+file systems.
+For some other file systems, values that have similar, but not
+identical, semantics to those described above may be returned.
+An example is msdosfs, which in case of FAT12 or FAT13 file systems
+reports the number of available and of free root directory entries
+instead of inodes
+.Po
+where 1 to 21 such directory entries are required to store
+each file or directory name or disk label
+.Pc .
 .Sh SEE ALSO
 .Xr fhstatfs 2 ,
 .Xr getfsstat 2
diff --git a/sys/fs/msdosfs/msdosfs_lookup.c b/sys/fs/msdosfs/msdosfs_lookup.c
--- a/sys/fs/msdosfs/msdosfs_lookup.c
+++ b/sys/fs/msdosfs/msdosfs_lookup.c
@@ -684,6 +684,7 @@
 		return error;
 	}
 	ndep = bptoep(pmp, bp, ddep->de_fndoffset);
+	rootde_alloced(ddep);
 
 	DE_EXTERNALIZE(ndep, dep);
 
@@ -721,6 +722,7 @@
 				ndep--;
 				ddep->de_fndoffset -= sizeof(struct direntry);
 			}
+			rootde_alloced(ddep);
 			if (!unix2winfn(un, unlen, (struct winentry *)ndep,
 					cnt++, chksum, pmp))
 				break;
@@ -1015,6 +1017,7 @@
 			 */
 			offset -= sizeof(struct direntry);
 			ep--->deName[0] = SLOT_DELETED;
+			rootde_freed(pdep);
 			if ((pmp->pm_flags & MSDOSFSMNT_NOWIN95)
 			    || !(offset & pmp->pm_crbomask)
 			    || ep->deAttributes != ATTR_WIN95)
diff --git a/sys/fs/msdosfs/msdosfs_vfsops.c b/sys/fs/msdosfs/msdosfs_vfsops.c
--- a/sys/fs/msdosfs/msdosfs_vfsops.c
+++ b/sys/fs/msdosfs/msdosfs_vfsops.c
@@ -409,6 +409,97 @@
 	return (0);
 }
 
+/*
+ * The FAT12 and FAT16 file systems use a limited size root directory that
+ * can be created with 1 to 65535 entries for files, directories, or a disk
+ * label (but DOS or Windows creates at most 512 root directory entries).
+ * This function calculates the number of free root directory entries by
+ * counting the non-deleted entries (not starting with 0xE5) and by adding
+ * the amount of never used entries (with the position indicated by an
+ * entry that starts with 0x00).
+ */
+static int
+rootdir_free(struct msdosfsmount* pmp)
+{
+	struct buf *bp;
+	struct direntry *dep;
+	u_long readsize;
+	int dirclu;
+	int diridx;
+	int dirmax;
+	int dirleft;
+	int ffree;
+
+	dirclu = pmp->pm_rootdirblk;
+
+	/*
+	 * The msdosfs code ignores pm_RootDirEnts and uses pm_rootdirsize
+	 * (measured in DEV_BSIZE) to prevent excess root dir allocations.
+	 */
+	dirleft = howmany(pmp->pm_rootdirsize * DEV_BSIZE,
+			  sizeof(struct direntry));
+
+	/* Read in chunks of default maximum root directory size */
+	readsize = 512 * sizeof(struct direntry);
+
+#ifdef MSDOSFS_DEBUG
+	printf("rootdir_free: blkpersec=%lu fatblksize=%lu dirsize=%lu "
+	    "firstclu=%lu dirclu=%d entries=%d rootdirsize=%lu "
+	    "bytespersector=%hu bytepercluster=%lu\n",
+	    pmp->pm_BlkPerSec, pmp->pm_fatblocksize, readsize,
+	    pmp->pm_firstcluster, dirclu, dirleft, pmp->pm_rootdirsize,
+	    pmp->pm_BytesPerSec, pmp->pm_bpcluster);
+#endif
+	ffree = dirleft;
+	while (dirleft > 0 && ffree > 0) {
+		if (readsize > dirleft * sizeof(struct direntry))
+			readsize = dirleft * sizeof(struct direntry);
+#ifdef MSDOSFS_DEBUG
+		printf("rootdir_free: dirclu=%d dirleft=%d readsize=%lu\n",
+		       dirclu, dirleft, readsize);
+#endif
+		if (bread(pmp->pm_devvp, dirclu, readsize, NOCRED, &bp) != 0) {
+			printf("rootdir_free: read error\n");
+			if (bp != NULL)
+				brelse(bp);
+			return (-1);
+		}
+		dirmax = readsize / sizeof(struct direntry);
+		for (diridx = 0; diridx < dirmax && dirleft > 0;
+		     diridx++, dirleft--) {
+			dep = (struct direntry*)bp->b_data + diridx;
+#ifdef MSDOSFS_DEBUG
+			if (dep->deName[0] == SLOT_DELETED)
+				printf("rootdir_free: idx=%d <deleted>\n",
+				    diridx);
+			else if (dep->deName[0] == SLOT_EMPTY)
+				printf("rootdir_free: idx=%d <end marker>\n",
+				    diridx);
+			else if (dep->deAttributes == ATTR_WIN95)
+				printf("rootdir_free: idx=%d <LFN part %d>\n",
+				    diridx, (dep->deName[0] & 0x1f) + 1);
+			else if (dep->deAttributes & ATTR_VOLUME)
+				printf("rootdir_free: idx=%d label='%11.11s'\n",
+				    diridx, dep->deName);
+			else if (dep->deAttributes & ATTR_DIRECTORY)
+				printf("rootdir_free: idx=%d dir='%11.11s'\n",
+				    diridx, dep->deName);
+			else
+				printf("rootdir_free: idx=%d file='%11.11s'\n",
+				    diridx, dep->deName);
+#endif
+			if (dep->deName[0] == SLOT_EMPTY)
+				dirleft = 0;
+			else if (dep->deName[0] != SLOT_DELETED)
+				ffree--;
+		}
+		brelse(bp);
+		bp = NULL;
+		dirclu += readsize / DEV_BSIZE;
+	}
+	return (ffree);
+}
+
 static int
 mountmsdosfs(struct vnode *odevvp, struct mount *mp)
 {
@@ -747,6 +838,15 @@
 			goto error_exit;
 		pmp->pm_fmod = 1;
 	}
+
+	if (FAT32(pmp)) {
+		pmp->pm_rootdirfree = 0;
+	} else {
+		pmp->pm_rootdirfree = rootdir_free(pmp);
+		if (pmp->pm_rootdirfree < 0)
+			goto error_exit;
+	}
+
 	mp->mnt_data =  pmp;
 	mp->mnt_stat.f_fsid.val[0] = dev2udev(dev);
 	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
@@ -948,8 +1048,9 @@
 	sbp->f_blocks = pmp->pm_maxcluster + 1;
 	sbp->f_bfree = pmp->pm_freeclustercount;
 	sbp->f_bavail = pmp->pm_freeclustercount;
-	sbp->f_files = pmp->pm_RootDirEnts;	/* XXX */
-	sbp->f_ffree = 0;	/* what to put in here? */
+	sbp->f_files =	howmany(pmp->pm_rootdirsize * DEV_BSIZE,
+				sizeof(struct direntry));
+	sbp->f_ffree = pmp->pm_rootdirfree;
 	return (0);
 }
 
diff --git a/sys/fs/msdosfs/msdosfsmount.h b/sys/fs/msdosfs/msdosfsmount.h
--- a/sys/fs/msdosfs/msdosfsmount.h
+++ b/sys/fs/msdosfs/msdosfsmount.h
@@ -108,6 +108,7 @@
 	u_int pm_fatmult;	/* these 2 values are used in FAT */
 	u_int pm_fatdiv;	/*	offset computation */
 	u_int pm_curfat;	/* current FAT for FAT32 (0 otherwise) */
+	int pm_rootdirfree;	/* number of free slots in FAT12/16 root directory */
 	u_int *pm_inusemap;	/* ptr to bitmap of in-use clusters */
 	uint64_t pm_flags;	/* see below */
 	void *pm_u2w;	/* Local->Unicode iconv handle */
@@ -222,6 +223,22 @@
 	 ? roottobn((pmp), (dirofs)) \
 	 : cntobn((pmp), (dirclu)))
 
+/*
+ * Increment the number of used entries in a fixed size FAT12/16 root
+ * directory
+ */
+#define rootde_alloced(dep)			   \
+	if ((dep)->de_StartCluster == MSDOSFSROOT) \
+		(dep)->de_pmp->pm_rootdirfree--;
+
+/*
+ * Decrement the number of used entries in a fixed size FAT12/16 root
+ * directory
+ */
+#define rootde_freed(dep)			   \
+	if ((dep)->de_StartCluster == MSDOSFSROOT) \
+		(dep)->de_pmp->pm_rootdirfree++;
+
 #define	MSDOSFS_LOCK_MP(pmp) \
 	lockmgr(&(pmp)->pm_fatlock, LK_EXCLUSIVE, NULL)
 #define	MSDOSFS_UNLOCK_MP(pmp) \