[PATCH v9 15/17] nfsd: Report export case-folding via NFSv3 PATHCONF
From: Chuck Lever <cel@kernel.org>
Date: 2026-04-22 23:30:53
Also in:
linux-cifs, linux-ext4, linux-f2fs-devel, linux-fsdevel, linux-nfs, linux-xfs
Subsystem:
filesystems (vfs and infrastructure), kernel nfsd, sunrpc, and lockd servers, the rest · Maintainers:
Alexander Viro, Christian Brauner, Chuck Lever, Jeff Layton, Linus Torvalds
From: Chuck Lever <redacted>
The hard-coded MSDOS_SUPER_MAGIC check in nfsd3_proc_pathconf()
only recognizes FAT filesystems as case-insensitive. Modern
filesystems like F2FS, exFAT, and CIFS support case-insensitive
directories, but NFSv3 clients cannot discover this capability.
Query the export's actual case behavior through ->fileattr_get
instead. This allows NFSv3 clients to correctly handle case
sensitivity for any filesystem that implements the fileattr
interface. Filesystems without ->fileattr_get continue to report
the default POSIX behavior (case-sensitive, case-preserving).
This change depends on commit ("fat: Implement fileattr_get for
case sensitivity"), which ensures FAT filesystems report their
case behavior correctly via the fileattr interface.
Signed-off-by: Chuck Lever <redacted>
---
fs/nfsd/nfs3proc.c | 18 ++++++++++--------
fs/nfsd/vfs.c | 29 +++++++++++++++++++++++++++++
fs/nfsd/vfs.h | 3 +++
3 files changed, 42 insertions(+), 8 deletions(-)
diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 42adc5461db0..7b094c5908f1 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c@@ -717,17 +717,19 @@ nfsd3_proc_pathconf(struct svc_rqst *rqstp) if (resp->status == nfs_ok) { struct super_block *sb = argp->fh.fh_dentry->d_sb; + bool case_insensitive, case_preserving; - /* Note that we don't care for remote fs's here */ - switch (sb->s_magic) { - case EXT2_SUPER_MAGIC: + if (sb->s_magic == EXT2_SUPER_MAGIC) { resp->p_link_max = EXT2_LINK_MAX; resp->p_name_max = EXT2_NAME_LEN; - break; - case MSDOS_SUPER_MAGIC: - resp->p_case_insensitive = 1; - resp->p_case_preserving = 0; - break; + } + + resp->status = nfsd_get_case_info(argp->fh.fh_dentry, + &case_insensitive, + &case_preserving); + if (resp->status == nfs_ok) { + resp->p_case_insensitive = case_insensitive; + resp->p_case_preserving = case_preserving; } }
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index eafdf7b7890f..6a7c6a691f2a 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c@@ -32,6 +32,7 @@ #include <linux/writeback.h> #include <linux/security.h> #include <linux/sunrpc/xdr.h> +#include <linux/fileattr.h> #include "xdr3.h"
@@ -2891,3 +2892,31 @@ nfsd_permission(struct svc_cred *cred, struct svc_export *exp, return err? nfserrno(err) : 0; } + +/** + * nfsd_get_case_info - get case sensitivity info for a dentry + * @dentry: dentry to query + * @case_insensitive: output, true if the filesystem is case-insensitive + * @case_preserving: output, true if the filesystem preserves case + * + * Filesystems without ->fileattr_get report POSIX defaults + * (case-sensitive, case-preserving). Outputs are unmodified on + * failure. + * + * Returns nfs_ok on success, or an nfserr on failure. + */ +__be32 +nfsd_get_case_info(struct dentry *dentry, bool *case_insensitive, + bool *case_preserving) +{ + struct file_kattr fa = {}; + int err; + + err = vfs_fileattr_get(dentry, &fa); + if (err && err != -ENOIOCTLCMD) + return nfserrno(err); + + *case_insensitive = fa.fsx_xflags & FS_XFLAG_CASEFOLD; + *case_preserving = !(fa.fsx_xflags & FS_XFLAG_CASENONPRESERVING); + return nfs_ok; +}
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index 702a844f2106..abf33389ee81 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h@@ -156,6 +156,9 @@ __be32 nfsd_readdir(struct svc_rqst *, struct svc_fh *, loff_t *, struct readdir_cd *, nfsd_filldir_t); __be32 nfsd_statfs(struct svc_rqst *, struct svc_fh *, struct kstatfs *, int access); +__be32 nfsd_get_case_info(struct dentry *dentry, + bool *case_insensitive, + bool *case_preserving); __be32 nfsd_permission(struct svc_cred *cred, struct svc_export *exp, struct dentry *dentry, int acc);
--
2.53.0