The branch main has been updated by kib:
URL:
https://cgit.FreeBSD.org/src/commit/?id=6450e7bbad0c68176f28b51773a3af5d6022c7dd
commit 6450e7bbad0c68176f28b51773a3af5d6022c7dd
Author: Olivier Certner <olce.free...@certner.fr>
AuthorDate: 2023-04-22 16:07:07 +0000
Commit: Konstantin Belousov <k...@freebsd.org>
CommitDate: 2023-04-28 01:27:54 +0000
vfs: Fix "emptydir" mount option
Fix vfs_emptydir(). It would consider directories containing directories
with name of the form 'X.' (X being any authorized byte) as empty. Also,
it would cause VOP_READDIR() to return an error on directories
containing enough whiteouts. While here, use a more decently sized
buffer as done elsewhere.
Remove ad-hoc iteration on the directory's content and instead use the
newly exported vn_dir_next_dirent() function (this is what fixes the
second problem mentioned above).
PR: 270988
Reviewed by: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D39775
---
sys/kern/vfs_subr.c | 115 ++++++++++++++++++++++++++++++----------------------
1 file changed, 67 insertions(+), 48 deletions(-)
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index eac6fa0ddb6a..3c783f7326d0 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -6391,65 +6391,84 @@ filt_vfsvnode(struct knote *kn, long hint)
int
vfs_emptydir(struct vnode *vp)
{
- struct uio uio;
- struct iovec iov;
- struct dirent *dirent, *dp, *endp;
- int error, eof;
-
- error = 0;
- eof = 0;
+ struct thread *const td = curthread;
+ char *dirbuf;
+ size_t dirbuflen, len;
+ off_t off;
+ int eofflag, error;
+ struct dirent *dp;
+ struct vattr va;
ASSERT_VOP_LOCKED(vp, "vfs_emptydir");
VNPASS(vp->v_type == VDIR, vp);
- dirent = malloc(sizeof(struct dirent), M_TEMP, M_WAITOK);
- iov.iov_base = dirent;
- iov.iov_len = sizeof(struct dirent);
-
- uio.uio_iov = &iov;
- uio.uio_iovcnt = 1;
- uio.uio_offset = 0;
- uio.uio_resid = sizeof(struct dirent);
- uio.uio_segflg = UIO_SYSSPACE;
- uio.uio_rw = UIO_READ;
- uio.uio_td = curthread;
-
- while (eof == 0 && error == 0) {
- error = VOP_READDIR(vp, &uio, curthread->td_ucred, &eof,
- NULL, NULL);
+ error = VOP_GETATTR(vp, &va, td->td_ucred);
+ if (error != 0)
+ return (error);
+
+ dirbuflen = max(DEV_BSIZE, GENERIC_MAXDIRSIZ);
+ if (dirbuflen < va.va_blocksize)
+ dirbuflen = va.va_blocksize;
+ dirbuf = malloc(dirbuflen, M_TEMP, M_WAITOK);
+
+ len = 0;
+ off = 0;
+ eofflag = 0;
+
+ for (;;) {
+ error = vn_dir_next_dirent(vp, td, dirbuf, dirbuflen,
+ &dp, &len, &off, &eofflag);
if (error != 0)
- break;
- endp = (void *)((uint8_t *)dirent +
- sizeof(struct dirent) - uio.uio_resid);
- for (dp = dirent; dp < endp;
- dp = (void *)((uint8_t *)dp + GENERIC_DIRSIZ(dp))) {
- if (dp->d_type == DT_WHT)
- continue;
- if (dp->d_namlen == 0)
- continue;
- if (dp->d_type != DT_DIR &&
- dp->d_type != DT_UNKNOWN) {
- error = ENOTEMPTY;
- break;
- }
- if (dp->d_namlen > 2) {
- error = ENOTEMPTY;
- break;
- }
- if (dp->d_namlen == 1 &&
- dp->d_name[0] != '.') {
+ goto end;
+
+ if (len == 0) {
+ /* EOF */
+ error = 0;
+ goto end;
+ }
+
+ /*
+ * Skip whiteouts. Unionfs operates on filesystems only and not
+ * on hierarchies, so these whiteouts would be shadowed on the
+ * system hierarchy but not for a union using the filesystem of
+ * their directories as the upper layer. Additionally, unionfs
+ * currently transparently exposes union-specific metadata of
+ * its upper layer, meaning that whiteouts can be seen through
+ * the union view in empty directories. Taking into account
+ * these whiteouts would then prevent mounting another
+ * filesystem on such effectively empty directories.
+ */
+ if (dp->d_type == DT_WHT)
+ continue;
+
+ /*
+ * Any file in the directory which is not '.' or '..' indicates
+ * the directory is not empty.
+ */
+ switch (dp->d_namlen) {
+ case 2:
+ if (dp->d_name[1] != '.') {
+ /* Can't be '..' (nor '.') */
error = ENOTEMPTY;
- break;
+ goto end;
}
- if (dp->d_namlen == 2 &&
- dp->d_name[1] != '.') {
+ /* FALLTHROUGH */
+ case 1:
+ if (dp->d_name[0] != '.') {
+ /* Can't be '..' nor '.' */
error = ENOTEMPTY;
- break;
+ goto end;
}
- uio.uio_resid = sizeof(struct dirent);
+ break;
+
+ default:
+ error = ENOTEMPTY;
+ goto end;
}
}
- free(dirent, M_TEMP);
+
+end:
+ free(dirbuf, M_TEMP);
return (error);
}
