[PATCH v11 12/15] isofs: Implement fileattr_get for case sensitivity

[Chuck Lever <cel@kernel.org>]

From: Chuck Lever <chuck.lever@oracle.com>

Upper layers such as NFSD need a way to query whether a
filesystem handles filenames in a case-sensitive manner so
they can provide correct semantics to remote clients. Without
this information, NFS exports of ISO 9660 filesystems cannot
advertise their filename case behavior.

Implement isofs_fileattr_get() to report ISO 9660 case handling
behavior via the FS_XFLAG_CASEFOLD flag. The 'check=r' (relaxed)
mount option enables case-insensitive lookups, and this setting
determines the value reported. By default, Joliet extensions
operate in relaxed mode while plain ISO 9660 uses strict
(case-sensitive) mode. All ISO 9660 variants are case-preserving,
meaning filenames are stored exactly as they appear on the disc.

Case handling is a superblock-wide property, so the callback
must report the same value for every inode type. Regular files
previously had no inode_operations; introduce
isofs_file_inode_operations to carry the callback. Symlinks
previously shared page_symlink_inode_operations; introduce
isofs_symlink_inode_operations, which wires page_get_link
alongside the callback, so that fileattr queries on a symlink
reach the isofs implementation instead of returning
-ENOIOCTLCMD. The flag is set in both fa->fsx_xflags and
fa->flags so FS_IOC_FSGETXATTR and FS_IOC_GETFLAGS agree.

Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Roland Mainz <roland.mainz@nrubsig.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/isofs/dir.c   | 24 ++++++++++++++++++++++++
 fs/isofs/inode.c |  3 ++-
 fs/isofs/isofs.h |  5 +++++
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/fs/isofs/dir.c b/fs/isofs/dir.c
index 2fd9948d606e..1db6b0db3808 100644
--- a/fs/isofs/dir.c
+++ b/fs/isofs/dir.c
@@ -14,6 +14,7 @@
 #include <linux/gfp.h>
 #include <linux/filelock.h>
 #include "isofs.h"
+#include <linux/fileattr.h>
 
 int isofs_name_translate(struct iso_directory_record *de, char *new, struct inode *inode)
 {
@@ -267,6 +268,17 @@ static int isofs_readdir(struct file *file, struct dir_context *ctx)
 	return result;
 }
 
+int isofs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+	struct isofs_sb_info *sbi = ISOFS_SB(dentry->d_sb);
+
+	if (sbi->s_check == 'r') {
+		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
+		fa->flags |= FS_CASEFOLD_FL;
+	}
+	return 0;
+}
+
 const struct file_operations isofs_dir_operations =
 {
 	.llseek = generic_file_llseek,
@@ -281,6 +293,18 @@ const struct file_operations isofs_dir_operations =
 const struct inode_operations isofs_dir_inode_operations =
 {
 	.lookup = isofs_lookup,
+	.fileattr_get = isofs_fileattr_get,
+};
+
+const struct inode_operations isofs_file_inode_operations =
+{
+	.fileattr_get = isofs_fileattr_get,
+};
+
+const struct inode_operations isofs_symlink_inode_operations =
+{
+	.get_link = page_get_link,
+	.fileattr_get = isofs_fileattr_get,
 };
 
 
diff --git a/fs/isofs/inode.c b/fs/isofs/inode.c
index efee53717f1c..68c286b7cc35 100644
--- a/fs/isofs/inode.c
+++ b/fs/isofs/inode.c
@@ -1427,6 +1427,7 @@ static int isofs_read_inode(struct inode *inode, int relocated)
 
 	/* Install the inode operations vector */
 	if (S_ISREG(inode->i_mode)) {
+		inode->i_op = &isofs_file_inode_operations;
 		inode->i_fop = &generic_ro_fops;
 		switch (ei->i_file_format) {
 #ifdef CONFIG_ZISOFS
@@ -1442,7 +1443,7 @@ static int isofs_read_inode(struct inode *inode, int relocated)
 		inode->i_op = &isofs_dir_inode_operations;
 		inode->i_fop = &isofs_dir_operations;
 	} else if (S_ISLNK(inode->i_mode)) {
-		inode->i_op = &page_symlink_inode_operations;
+		inode->i_op = &isofs_symlink_inode_operations;
 		inode_nohighmem(inode);
 		inode->i_data.a_ops = &isofs_symlink_aops;
 	} else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
diff --git a/fs/isofs/isofs.h b/fs/isofs/isofs.h
index 506555837533..a3cda3430020 100644
--- a/fs/isofs/isofs.h
+++ b/fs/isofs/isofs.h
@@ -197,7 +197,12 @@ isofs_normalize_block_and_offset(struct iso_directory_record* de,
 	}
 }
 
+struct file_kattr;
+int isofs_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
+
 extern const struct inode_operations isofs_dir_inode_operations;
+extern const struct inode_operations isofs_file_inode_operations;
+extern const struct inode_operations isofs_symlink_inode_operations;
 extern const struct file_operations isofs_dir_operations;
 extern const struct address_space_operations isofs_symlink_aops;
 extern const struct export_operations isofs_export_ops;

-- 
2.53.0