vboxsf: Implement fileattr_get for case sensitivity

Upper layers such as NFSD need a way to query whether a
filesystem handles filenames in a case-sensitive manner. Report
VirtualBox shared folder case handling behavior via the
FS_XFLAG_CASEFOLD flag.

The case sensitivity property is queried from the VirtualBox host
service at mount time and cached in struct vboxsf_sbi. The host
determines case sensitivity based on the underlying host filesystem
(for example, Windows NTFS is case-insensitive while Linux ext4 is
case-sensitive).

VirtualBox shared folders always preserve filename case exactly
as provided by the guest. The host interface does not expose a
separate case-preserving property; leaving
FS_XFLAG_CASENONPRESERVING unset reports the POSIX-default
case-preserving behavior, which matches vboxsf semantics.

The callback is registered in all three inode_operations
structures (directory, file, and symlink) to ensure consistent
reporting across all inode types.

Reviewed-by: Roland Mainz <roland.mainz@nrubsig.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://patch.msgid.link/20260507-case-sensitivity-v14-11-e62cc8200435@oracle.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/vboxsf/dir.c b/fs/vboxsf/dir.c
index 42bedc4ec7af7709c564a7174805d185ce86f854..c5bd3271aa9616f6671cdf076a0ce504a7cab5bf 100644 (file)
--- a/fs/vboxsf/dir.c
+++ b/fs/vboxsf/dir.c
@@ -477,4 +477,5 @@ const struct inode_operations vboxsf_dir_iops = {
        .symlink = vboxsf_dir_symlink,
        .getattr = vboxsf_getattr,
        .setattr = vboxsf_setattr,
+       .fileattr_get = vboxsf_fileattr_get,
 };

diff --git a/fs/vboxsf/file.c b/fs/vboxsf/file.c
index 7a7a3fbb26514ec73bed4bd375d87f9a131623ce..943953867e18e94bc07d143f980fec023a3989ef 100644 (file)
--- a/fs/vboxsf/file.c
+++ b/fs/vboxsf/file.c
@@ -222,7 +222,8 @@ const struct file_operations vboxsf_reg_fops = {
 
 const struct inode_operations vboxsf_reg_iops = {
        .getattr = vboxsf_getattr,
-       .setattr = vboxsf_setattr
+       .setattr = vboxsf_setattr,
+       .fileattr_get = vboxsf_fileattr_get,
 };
 
 static int vboxsf_read_folio(struct file *file, struct folio *folio)
@@ -389,5 +390,6 @@ static const char *vboxsf_get_link(struct dentry *dentry, struct inode *inode,
 }
 
 const struct inode_operations vboxsf_lnk_iops = {
-       .get_link = vboxsf_get_link
+       .get_link = vboxsf_get_link,
+       .fileattr_get = vboxsf_fileattr_get,
 };

diff --git a/fs/vboxsf/super.c b/fs/vboxsf/super.c
index a618cb093e007249e8b43b77c1c079b046f575b6..a61fbab51d370cc1eb98c5fc15049ccf060e2bce 100644 (file)
--- a/fs/vboxsf/super.c
+++ b/fs/vboxsf/super.c
@@ -185,6 +185,13 @@ static int vboxsf_fill_super(struct super_block *sb, struct fs_context *fc)
        if (err)
                goto fail_unmap;
 
+       /*
+        * A failed query leaves sbi->case_insensitive false, so the
+        * mount defaults to reporting case-sensitive behavior. Do not
+        * fail the mount over an advisory attribute.
+        */
+       vboxsf_query_case_sensitive(sbi);
+
        sb->s_magic = VBOXSF_SUPER_MAGIC;
        sb->s_blocksize = 1024;
        sb->s_maxbytes = MAX_LFS_FILESIZE;

diff --git a/fs/vboxsf/utils.c b/fs/vboxsf/utils.c
index 440e8c50629d32dc03c24b33a0bb2081cafc4805..298bfc93255c03d12255c568327a46682c30d6e8 100644 (file)
--- a/fs/vboxsf/utils.c
+++ b/fs/vboxsf/utils.c
@@ -11,6 +11,7 @@
 #include <linux/sizes.h>
 #include <linux/pagemap.h>
 #include <linux/vfs.h>
+#include <linux/fileattr.h>
 #include "vfsmod.h"
 
 struct inode *vboxsf_new_inode(struct super_block *sb)
@@ -567,3 +568,32 @@ int vboxsf_dir_read_all(struct vboxsf_sbi *sbi, struct vboxsf_dir_info *sf_d,
 
        return err;
 }
+
+int vboxsf_query_case_sensitive(struct vboxsf_sbi *sbi)
+{
+       struct shfl_volinfo volinfo = {};
+       u32 buf_len;
+       int err;
+
+       buf_len = sizeof(volinfo);
+       err = vboxsf_fsinfo(sbi->root, 0, SHFL_INFO_GET | SHFL_INFO_VOLUME,
+                           &buf_len, &volinfo);
+       if (err)
+               return err;
+       if (buf_len < sizeof(volinfo))
+               return 0;
+
+       sbi->case_insensitive = !volinfo.properties.case_sensitive;
+       return 0;
+}
+
+int vboxsf_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+       struct vboxsf_sbi *sbi = VBOXSF_SBI(dentry->d_sb);
+
+       if (sbi->case_insensitive) {
+               fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
+               fa->flags |= FS_CASEFOLD_FL;
+       }
+       return 0;
+}

diff --git a/fs/vboxsf/vfsmod.h b/fs/vboxsf/vfsmod.h
index 05973eb89d5283acf4766909537295d013ebf4f7..b61afd0ce842d2a83c005e334db6f90d79abfc82 100644 (file)
--- a/fs/vboxsf/vfsmod.h
+++ b/fs/vboxsf/vfsmod.h
@@ -47,6 +47,7 @@ struct vboxsf_sbi {
        u32 next_generation;
        u32 root;
        int bdi_id;
+       bool case_insensitive;
 };
 
 /* per-inode information */
@@ -111,6 +112,11 @@ void vboxsf_dir_info_free(struct vboxsf_dir_info *p);
 int vboxsf_dir_read_all(struct vboxsf_sbi *sbi, struct vboxsf_dir_info *sf_d,
                        u64 handle);
 
+int vboxsf_query_case_sensitive(struct vboxsf_sbi *sbi);
+
+struct file_kattr;
+int vboxsf_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
+
 /* from vboxsf_wrappers.c */
 int vboxsf_connect(void);
 void vboxsf_disconnect(void);