The branch main has been updated by arichardson: URL: https://cgit.FreeBSD.org/src/commit/?id=96b2f4a9124158f27c4c27c32f6fa1a6018250fb
commit 96b2f4a9124158f27c4c27c32f6fa1a6018250fb Author: Alex Richardson <[email protected]> AuthorDate: 2026-05-07 04:22:23 +0000 Commit: Alex Richardson <[email protected]> CommitDate: 2026-05-07 04:23:04 +0000 p9fs: implement basic pathconf support This is needed for various pjdfstest tests which fail with syntax errors if pathconf _PC_NAME_MAX/_PC_PATH_MAX return -1. For NAME_MAX we can use the 9P2000.L Tstatfs call to get namelen from the host. While this could theoretically be different for nested filesystems in the shared mount it is a much better guess than just returning 255. There does not seem to be a way to get the host PATH_MAX, so we just return the conservative kernel default. Found while fixing https://github.com/CTSRD-CHERI/cheribsd/issues/2617. Reviewed by: markj, kib MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D56493 --- sys/fs/p9fs/p9fs.h | 1 + sys/fs/p9fs/p9fs_vnops.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 72 insertions(+), 2 deletions(-) diff --git a/sys/fs/p9fs/p9fs.h b/sys/fs/p9fs/p9fs.h index 2470734fef4d..b469495ef69e 100644 --- a/sys/fs/p9fs/p9fs.h +++ b/sys/fs/p9fs/p9fs.h @@ -154,6 +154,7 @@ struct p9fs_session { struct mtx p9fs_mtx; /* mutex used for guarding the chain.*/ STAILQ_HEAD( ,p9fs_node) virt_node_list; /* list of p9fs nodes in this session*/ struct p9_fid *mnt_fid; /* to save nobody 's fid for unmounting as root user */ + unsigned int name_max; /* cached max filename length */ }; struct p9fs_mount { diff --git a/sys/fs/p9fs/p9fs_vnops.c b/sys/fs/p9fs/p9fs_vnops.c index 7141e9700602..ad739a219acb 100644 --- a/sys/fs/p9fs/p9fs_vnops.c +++ b/sys/fs/p9fs/p9fs_vnops.c @@ -37,10 +37,12 @@ #include <sys/fcntl.h> #include <sys/namei.h> #include <sys/priv.h> -#include <sys/stat.h> -#include <sys/vnode.h> #include <sys/rwlock.h> +#include <sys/stat.h> +#include <sys/syslimits.h> +#include <sys/unistd.h> #include <sys/vmmeter.h> +#include <sys/vnode.h> #include <vm/vm.h> #include <vm/vm_extern.h> @@ -2248,6 +2250,72 @@ p9fs_delayed_setsize(struct vop_delayed_setsize_args *ap) return (0); } +static unsigned int +p9fs_get_name_max(struct p9fs_node *np) +{ + struct p9fs_session *vses = np->p9fs_ses; + struct p9_statfs statfs; + struct p9_fid *vfid; + unsigned int name_max; + int error = 0; + + name_max = atomic_load_int(&vses->name_max); + if (name_max != 0) + return (name_max); + + P9_DEBUG(VOPS, "%s: querying _PC_NAME_MAX\n", __func__); + vfid = p9fs_get_fid(vses->clnt, np, NULL, VFID, -1, &error); + if (vfid != NULL) { + error = p9_client_statfs(vfid, &statfs); + if (error == 0) { + /* + * Note that this is not strictly correct if you have + * nested mounts on the host (e.g. when using qemu with + * multidevs=remap), but is a better estimate than just + * returning 255. + */ + name_max = statfs.namelen; + } + } + P9_DEBUG(VOPS, "%s: max_name=%u error=%d\n", __func__, name_max, error); + if (error != 0 || name_max == 0) { + printf("p9fs: warning: failed to query name_max (error %d), " + "using fallback %d\n", error, NAME_MAX); + name_max = NAME_MAX; /* fallback and prevent retrying */ + } + atomic_store_int(&vses->name_max, name_max); + return (name_max); +} + +/* + * Return POSIX pathconf information applicable to p9fs filesystems. + */ +static int +p9fs_pathconf(struct vop_pathconf_args *ap) +{ + int error = 0; + struct vnode *vp = ap->a_vp; + struct p9fs_node *np = P9FS_VTON(vp); + + switch (ap->a_name) { + case _PC_NAME_MAX: + *ap->a_retval = p9fs_get_name_max(np); + break; + case _PC_SYMLINK_MAX: + case _PC_PATH_MAX: + /* + * These are conservative estimates, the real value depends on + * the host file system. + */ + *ap->a_retval = MAXPATHLEN; + break; + default: + error = vop_stdpathconf(ap); + break; + } + return (error); +} + struct vop_vector p9fs_vnops = { .vop_default = &default_vnodeops, .vop_lookup = p9fs_lookup, @@ -2257,6 +2325,7 @@ struct vop_vector p9fs_vnops = { .vop_delayed_setsize = p9fs_delayed_setsize, .vop_getattr = p9fs_getattr_dotl, .vop_setattr = p9fs_setattr_dotl, + .vop_pathconf = p9fs_pathconf, .vop_reclaim = p9fs_reclaim, .vop_inactive = p9fs_inactive, .vop_readdir = p9fs_readdir,
