Add error handling to minix filesystem for inode corruption detection

We would like to provide early and specific warnings of filesystem
corruption without running into generic WARN_ONs and BUG_ONs.
Towards this goal, ext4, e.g., has a EFSCORRUPTED errno and a
standardized inode corruption message format. This patch adds this
errno and message format to the minix filesystem.

Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
Link: https://patch.msgid.link/20251104143005.3283980-2-jkoolstra@xs4all.nl
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: LATENTBOUNCE

fs/minix/inode.c

@@ -26,6 +26,22 @@ static int minix_write_inode(struct inode *inode,
 		struct writeback_control *wbc);
 static int minix_statfs(struct dentry *dentry, struct kstatfs *buf);
 
+void __minix_error_inode(struct inode *inode, const char *function,
+			 unsigned int line, const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+	printk(KERN_CRIT "minix-fs error (device %s): %s:%d: "
+	       "inode #%lu: comm %s: %pV\n",
+	       inode->i_sb->s_id, function, line, inode->i_ino,
+	       current->comm, &vaf);
+	va_end(args);
+}
+
 static void minix_evict_inode(struct inode *inode)
 {
 	truncate_inode_pages_final(&inode->i_data);

fs/minix/minix.h

@@ -42,6 +42,9 @@ struct minix_sb_info {
 	unsigned short s_version;
 };
 
+void __minix_error_inode(struct inode *inode, const char *function,
+			 unsigned int line, const char *fmt, ...);
+
 struct inode *minix_iget(struct super_block *, unsigned long);
 struct minix_inode *minix_V1_raw_inode(struct super_block *, ino_t, struct buffer_head **);
 struct minix2_inode *minix_V2_raw_inode(struct super_block *, ino_t, struct buffer_head **);
@@ -168,4 +171,10 @@ static inline int minix_test_bit(int nr, const void *vaddr)
 
 #endif
 
+#define minix_error_inode(inode, fmt, ...)			\
+	__minix_error_inode((inode), __func__, __LINE__,	\
+			    (fmt), ##__VA_ARGS__)
+
+#define EFSCORRUPTED	EUCLEAN		/* Filesystem is corrupted */
+
 #endif /* FS_MINIX_H */