kern/file: Implement filesystem reference counting

The grub_file_open() and grub_file_close() should be the only places
that allow a reference to a filesystem to stay open. So, add grub_dl_t
to grub_fs_t and set this in the GRUB_MOD_INIT() for each filesystem to
avoid issues when filesystems forget to do it themselves or do not track
their own references, e.g. squash4.

The fs_label(), fs_uuid(), fs_mtime() and fs_read() should all ref and
unref in the same function but it is essentially redundant in GRUB
single threaded model.

Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/fs/affs.c

@@ -703,6 +703,7 @@ static struct grub_fs grub_affs_fs =
 
 GRUB_MOD_INIT(affs)
 {
+  grub_affs_fs.mod = mod;
   grub_fs_register (&grub_affs_fs);
   my_mod = mod;
 }

grub-core/fs/bfs.c

@@ -1106,6 +1106,7 @@ GRUB_MOD_INIT (bfs)
 {
   COMPILE_TIME_ASSERT (1 << LOG_EXTENT_SIZE ==
 		       sizeof (struct grub_bfs_extent));
+  grub_bfs_fs.mod = mod;
   grub_fs_register (&grub_bfs_fs);
 }
 

grub-core/fs/btrfs.c

@@ -2413,6 +2413,7 @@ static struct grub_fs grub_btrfs_fs = {
 
 GRUB_MOD_INIT (btrfs)
 {
+  grub_btrfs_fs.mod = mod;
   grub_fs_register (&grub_btrfs_fs);
 }
 

grub-core/fs/cbfs.c

@@ -390,6 +390,7 @@ GRUB_MOD_INIT (cbfs)
 #if (defined (__i386__) || defined (__x86_64__)) && !defined (GRUB_UTIL) && !defined (GRUB_MACHINE_EMU) && !defined (GRUB_MACHINE_XEN)
   init_cbfsdisk ();
 #endif
+  grub_cbfs_fs.mod = mod;
   grub_fs_register (&grub_cbfs_fs);
 }
 

grub-core/fs/cpio.c

@@ -52,6 +52,7 @@ read_number (const grub_uint16_t *arr, grub_size_t size)
 
 GRUB_MOD_INIT (cpio)
 {
+  grub_cpio_fs.mod = mod;
   grub_fs_register (&grub_cpio_fs);
 }
 

grub-core/fs/cpio_be.c

@@ -52,6 +52,7 @@ read_number (const grub_uint16_t *arr, grub_size_t size)
 
 GRUB_MOD_INIT (cpio_be)
 {
+  grub_cpio_fs.mod = mod;
   grub_fs_register (&grub_cpio_fs);
 }
 

grub-core/fs/erofs.c

@@ -991,6 +991,7 @@ static struct grub_fs grub_erofs_fs = {
 
 GRUB_MOD_INIT (erofs)
 {
+  grub_erofs_fs.mod = mod;
   grub_fs_register (&grub_erofs_fs);
 }
 

grub-core/fs/ext2.c

@@ -1131,6 +1131,7 @@ static struct grub_fs grub_ext2_fs =
 
 GRUB_MOD_INIT(ext2)
 {
+  grub_ext2_fs.mod = mod;
   grub_fs_register (&grub_ext2_fs);
   my_mod = mod;
 }

grub-core/fs/f2fs.c

@@ -1353,6 +1353,7 @@ static struct grub_fs grub_f2fs_fs = {
 
 GRUB_MOD_INIT (f2fs)
 {
+  grub_f2fs_fs.mod = mod;
   grub_fs_register (&grub_f2fs_fs);
   my_mod = mod;
 }

grub-core/fs/fat.c

@@ -1312,6 +1312,7 @@ GRUB_MOD_INIT(fat)
 #endif
 {
   COMPILE_TIME_ASSERT (sizeof (struct grub_fat_dir_entry) == 32);
+  grub_fat_fs.mod = mod;
   grub_fs_register (&grub_fat_fs);
   my_mod = mod;
 }

grub-core/fs/hfs.c

@@ -1434,6 +1434,7 @@ static struct grub_fs grub_hfs_fs =
 
 GRUB_MOD_INIT(hfs)
 {
+  grub_hfs_fs.mod = mod;
   if (!grub_is_lockdown ())
     grub_fs_register (&grub_hfs_fs);
   my_mod = mod;

grub-core/fs/hfsplus.c

@@ -1176,6 +1176,7 @@ static struct grub_fs grub_hfsplus_fs =
 
 GRUB_MOD_INIT(hfsplus)
 {
+  grub_hfsplus_fs.mod = mod;
   grub_fs_register (&grub_hfsplus_fs);
   my_mod = mod;
 }

grub-core/fs/iso9660.c

@@ -1260,6 +1260,7 @@ static struct grub_fs grub_iso9660_fs =
 
 GRUB_MOD_INIT(iso9660)
 {
+  grub_iso9660_fs.mod = mod;
   grub_fs_register (&grub_iso9660_fs);
   my_mod = mod;
 }

grub-core/fs/jfs.c

@@ -1004,6 +1004,7 @@ static struct grub_fs grub_jfs_fs =
 
 GRUB_MOD_INIT(jfs)
 {
+  grub_jfs_fs.mod = mod;
   grub_fs_register (&grub_jfs_fs);
   my_mod = mod;
 }

grub-core/fs/minix.c

@@ -734,6 +734,7 @@ GRUB_MOD_INIT(minix)
 #endif
 #endif
 {
+  grub_minix_fs.mod = mod;
   grub_fs_register (&grub_minix_fs);
   my_mod = mod;
 }

grub-core/fs/newc.c

@@ -64,6 +64,7 @@ read_number (const char *str, grub_size_t size)
 
 GRUB_MOD_INIT (newc)
 {
+  grub_cpio_fs.mod = mod;
   grub_fs_register (&grub_cpio_fs);
 }
 

grub-core/fs/nilfs2.c

@@ -1231,6 +1231,7 @@ GRUB_MOD_INIT (nilfs2)
 				  grub_nilfs2_dat_entry));
   COMPILE_TIME_ASSERT (1 << LOG_INODE_SIZE
 		       == sizeof (struct grub_nilfs2_inode));
+  grub_nilfs2_fs.mod = mod;
   grub_fs_register (&grub_nilfs2_fs);
   my_mod = mod;
 }

grub-core/fs/ntfs.c

@@ -1541,6 +1541,7 @@ static struct grub_fs grub_ntfs_fs =
 
 GRUB_MOD_INIT (ntfs)
 {
+  grub_ntfs_fs.mod = mod;
   grub_fs_register (&grub_ntfs_fs);
   my_mod = mod;
 }

grub-core/fs/odc.c

@@ -52,6 +52,7 @@ read_number (const char *str, grub_size_t size)
 
 GRUB_MOD_INIT (odc)
 {
+  grub_cpio_fs.mod = mod;
   grub_fs_register (&grub_cpio_fs);
 }
 

grub-core/fs/proc.c

@@ -192,6 +192,7 @@ static struct grub_fs grub_procfs_fs =
 
 GRUB_MOD_INIT (procfs)
 {
+  grub_procfs_fs.mod = mod;
   grub_disk_dev_register (&grub_procfs_dev);
   grub_fs_register (&grub_procfs_fs);
 }

grub-core/fs/reiserfs.c

@@ -1417,6 +1417,7 @@ static struct grub_fs grub_reiserfs_fs =
 
 GRUB_MOD_INIT(reiserfs)
 {
+  grub_reiserfs_fs.mod = mod;
   grub_fs_register (&grub_reiserfs_fs);
   my_mod = mod;
 }

grub-core/fs/romfs.c

@@ -475,6 +475,7 @@ static struct grub_fs grub_romfs_fs =
 
 GRUB_MOD_INIT(romfs)
 {
+  grub_romfs_fs.mod = mod;
   grub_fs_register (&grub_romfs_fs);
 }
 

grub-core/fs/sfs.c

@@ -779,6 +779,7 @@ static struct grub_fs grub_sfs_fs =
 
 GRUB_MOD_INIT(sfs)
 {
+  grub_sfs_fs.mod = mod;
   grub_fs_register (&grub_sfs_fs);
   my_mod = mod;
 }

grub-core/fs/squash4.c

@@ -1044,6 +1044,7 @@ static struct grub_fs grub_squash_fs =
 
 GRUB_MOD_INIT(squash4)
 {
+  grub_squash_fs.mod = mod;
   grub_fs_register (&grub_squash_fs);
 }
 

grub-core/fs/tar.c

@@ -354,6 +354,7 @@ static struct grub_fs grub_cpio_fs = {
 
 GRUB_MOD_INIT (tar)
 {
+  grub_cpio_fs.mod = mod;
   grub_fs_register (&grub_cpio_fs);
 }
 

grub-core/fs/udf.c

@@ -1455,6 +1455,7 @@ static struct grub_fs grub_udf_fs = {
 
 GRUB_MOD_INIT (udf)
 {
+  grub_udf_fs.mod = mod;
   grub_fs_register (&grub_udf_fs);
   my_mod = mod;
 }

grub-core/fs/ufs.c

@@ -899,6 +899,7 @@ GRUB_MOD_INIT(ufs1)
 #endif
 #endif
 {
+  grub_ufs_fs.mod = mod;
   grub_fs_register (&grub_ufs_fs);
   my_mod = mod;
 }

grub-core/fs/xfs.c

@@ -1304,6 +1304,7 @@ static struct grub_fs grub_xfs_fs =
 
 GRUB_MOD_INIT(xfs)
 {
+  grub_xfs_fs.mod = mod;
   grub_fs_register (&grub_xfs_fs);
   my_mod = mod;
 }

grub-core/fs/zfs/zfs.c

@@ -4464,6 +4464,7 @@ static struct grub_fs grub_zfs_fs = {
 GRUB_MOD_INIT (zfs)
 {
   COMPILE_TIME_ASSERT (sizeof (zap_leaf_chunk_t) == ZAP_LEAF_CHUNKSIZE);
+  grub_zfs_fs.mod = mod;
   grub_fs_register (&grub_zfs_fs);
 #ifndef GRUB_UTIL
   my_mod = mod;

grub-core/kern/file.c

@@ -25,6 +25,7 @@
 #include <grub/fs.h>
 #include <grub/device.h>
 #include <grub/i18n.h>
+#include <grub/dl.h>
 
 void (*EXPORT_VAR (grub_grubnet_fini)) (void);
 
@@ -117,6 +118,9 @@ grub_file_open (const char *name, enum grub_file_type type)
   if (file->data == NULL)
     goto fail;
 
+  if (file->fs->mod)
+    grub_dl_ref (file->fs->mod);
+
   file->name = grub_strdup (name);
   grub_errno = GRUB_ERR_NONE;
 
@@ -197,6 +201,9 @@ grub_file_read (grub_file_t file, void *buf, grub_size_t len)
 grub_err_t
 grub_file_close (grub_file_t file)
 {
+  if (file->fs->mod)
+    grub_dl_unref (file->fs->mod);
+
   if (file->fs->fs_close)
     (file->fs->fs_close) (file);
 

include/grub/fs.h

@@ -23,6 +23,7 @@
 #include <grub/device.h>
 #include <grub/symbol.h>
 #include <grub/types.h>
+#include <grub/dl.h>
 
 #include <grub/list.h>
 /* For embedding types.  */
@@ -57,6 +58,9 @@ struct grub_fs
   /* My name.  */
   const char *name;
 
+  /* My module */
+  grub_dl_t mod;
+
   /* Call HOOK with each file under DIR.  */
   grub_err_t (*fs_dir) (grub_device_t device, const char *path,
 		     grub_fs_dir_hook_t hook, void *hook_data);