[PATCH 13/21] tune2fs: Add support for changing number of reserved inodes

[Jan Kara <jack@suse.com>]

Signed-off-by: Jan Kara <jack@suse.com>
---
 misc/tune2fs.8.in |   5 +++
 misc/tune2fs.c    | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 115 insertions(+)

diff --git a/misc/tune2fs.8.in b/misc/tune2fs.8.in
index 4373fc49b255..922705329112 100644
--- a/misc/tune2fs.8.in
+++ b/misc/tune2fs.8.in
@@ -236,6 +236,11 @@ program.
 This superblock setting is only honored in 2.6.35+ kernels;
 and not at all by the ext2 and ext3 file system drivers.
 .TP
+.BI reserved_inodes= number_of_reserved_inodes
+Set the number of inodes reserved for system files. This number must be
+at least 10. Currently 10 is enough but future features may require additional
+reserved inodes. Reserving more inodes requires full file system scan so it
+can take a long time.
 .B test_fs
 Set a flag in the filesystem superblock indicating that it may be
 mounted using experimental kernel code, such as the ext4dev filesystem.
diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index e7e5ccde25c2..873a7e2b08c2 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -92,6 +92,7 @@ static char *features_cmd;
 static char *mntopts_cmd;
 static int stride, stripe_width;
 static int stride_set, stripe_width_set;
+static unsigned long new_first_ino;
 static char *extended_cmd;
 static unsigned long new_inode_size;
 static char *ext_mount_opts;
@@ -2300,6 +2301,42 @@ static int parse_extended_opts(ext2_filsys fs, const char *opts)
 				continue;
 			}
 			ext_mount_opts = strdup(arg);
+		} else if (!strcmp(token, "reserved_inodes")) {
+			if (!arg) {
+				r_usage++;
+				continue;
+			}
+			new_first_ino = strtoul(arg, &p, 0);
+			if (*p || new_first_ino == ULONG_MAX) {
+				fprintf(stderr,
+					_("Invalid number of reserved inodes "
+					  "%s\n"),
+					arg);
+				r_usage++;
+				continue;
+			}
+			/* Ino 0 is invalid so bump by 1... */
+			new_first_ino++;
+			if (new_first_ino < EXT2_GOOD_OLD_FIRST_INO) {
+				fprintf(stderr,
+					_("Too few reserved inodes "
+				          "%s (must be at least %u)\n"),
+				        arg, EXT2_GOOD_OLD_FIRST_INO - 1);
+				r_usage++;
+				continue;
+			}
+			if (new_first_ino > fs->super->s_inodes_count) {
+				fprintf(stderr,
+					_("Too many reserved inodes %s "
+					  "(must be at most %u)\n"),
+					arg, fs->super->s_inodes_count - 1);
+				r_usage++;
+				continue;
+			}
+			/*
+			 * Here should go further feature tests to disallow
+			 * admin to free used system inode
+			 */
 		} else
 			r_usage++;
 	}
@@ -2314,6 +2351,7 @@ static int parse_extended_opts(ext2_filsys fs, const char *opts)
 			"\tmount_opts=<extended default mount options>\n"
 			"\tstride=<RAID per-disk chunk size in blocks>\n"
 			"\tstripe_width=<RAID stride*data disks in blocks>\n"
+			"\treserved_inodes=<number of reserved inodes>\n"
 			"\ttest_fs\n"
 			"\t^test_fs\n"));
 		free(buf);
@@ -2988,6 +3026,75 @@ fs_update_journal_user(struct ext2_super_block *sb, __u8 old_uuid[UUID_SIZE])
 	return 0;
 }
 
+/* Zero range of inodes and mark them as free / used */
+static errcode_t zero_inodes_range(ext2_filsys fs, ext2_ino_t start,
+				   ext2_ino_t end, int inuse)
+{
+	char *inode;
+	int length = EXT2_INODE_SIZE(fs->super);
+	ext2_ino_t ino;
+	errcode_t retval;
+
+	retval = ext2fs_get_memzero(length, &inode);
+	if (retval)
+		return retval;
+
+	for (ino = start; ino <= end; ino++) {
+		ext2fs_inode_alloc_stats(fs, ino, inuse);
+		retval = ext2fs_write_inode_full(fs, ino,
+						 (struct ext2_inode *)inode,
+						 length);
+		if (retval)
+			break;
+	}
+	ext2fs_free_mem(inode);
+
+	return retval;
+}
+
+static errcode_t update_reserved_inodes(ext2_filsys fs)
+{
+	errcode_t retval = 0;
+	ext2fs_inode_bitmap imap;
+	ext2_ino_t ino, first_ino = fs->super->s_first_ino;
+
+	if (new_first_ino == first_ino)
+		return 0;
+
+	/* Group descriptors will need writing as well */
+	fs->flags &= ~EXT2_FLAG_SUPER_ONLY;
+
+	/* Freeing reserved inodes is easy */
+	if (new_first_ino < first_ino) {
+		retval = zero_inodes_range(fs, new_first_ino, first_ino - 1,
+					   -1);
+		if (retval)
+			return retval;
+		goto out;
+	}
+
+	retval = ext2fs_allocate_inode_bitmap(fs, "inodes to move", &imap);
+	if (retval)
+		return retval;
+
+	for (ino = fs->super->s_first_ino; ino < new_first_ino; ino++)
+		ext2fs_mark_inode_bitmap2(imap, ino);
+
+	retval = ext2fs_move_inodes(fs, imap);
+	ext2fs_free_inode_bitmap(imap);
+	if (retval)
+		return retval;
+
+	retval = zero_inodes_range(fs, first_ino, new_first_ino - 1, +1);
+	if (retval)
+		return retval;
+out:
+	fs->super->s_first_ino = new_first_ino;
+	ext2fs_mark_super_dirty(fs);
+
+	return 0;
+}
+
 int main(int argc, char **argv)
 {
 	errcode_t retval;
@@ -3413,6 +3520,9 @@ retry_open:
 		}
 	}
 
+	if (new_first_ino)
+		update_reserved_inodes(fs);
+
 	if (rewrite_checksums)
 		rewrite_metadata_checksums(fs);
 
-- 
2.1.4