The branch stable/15 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=77a5c63f79236301dece4f3045e254ccc5f49716
commit 77a5c63f79236301dece4f3045e254ccc5f49716 Author: Konstantin Belousov <[email protected]> AuthorDate: 2025-08-20 19:07:43 +0000 Commit: Konstantin Belousov <[email protected]> CommitDate: 2025-11-01 00:43:13 +0000 struct file: add DFLAG_FORK, indicate copying on fork (cherry picked from commit 1265516c5c610fbc0d65451140e3f17b358cd015) --- sys/kern/kern_descrip.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++-- sys/sys/file.h | 6 +++++- 2 files changed, 54 insertions(+), 3 deletions(-) diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c index 057235574eb5..6934a5a83081 100644 --- a/sys/kern/kern_descrip.c +++ b/sys/kern/kern_descrip.c @@ -2510,10 +2510,13 @@ fdcopy(struct filedesc *fdp) { struct filedesc *newfdp; struct filedescent *nfde, *ofde; + struct file *fp; int i, lastfile; + bool fork_pass; MPASS(fdp != NULL); + fork_pass = false; newfdp = fdinit(); FILEDESC_SLOCK(fdp); for (;;) { @@ -2524,10 +2527,35 @@ fdcopy(struct filedesc *fdp) fdgrowtable(newfdp, lastfile + 1); FILEDESC_SLOCK(fdp); } - /* copy all passable descriptors (i.e. not kqueue) */ + + /* + * Copy all passable descriptors (i.e. not kqueue), and + * prepare to handle copyable but not passable descriptors + * (kqueues). + * + * The pass to handle copying is performed after all passable + * files are installed into the new file descriptor's table, + * since kqueues need all referenced file descriptors already + * valid, including other kqueues. For the same reason the + * copying is done in two passes by itself, first installing + * not fully initialized ('empty') copyable files into the new + * fd table, and then giving the subsystems a second chance to + * really fill the copied file backing structure with the + * content. + */ newfdp->fd_freefile = fdp->fd_freefile; FILEDESC_FOREACH_FDE(fdp, i, ofde) { - if ((ofde->fde_file->f_ops->fo_flags & DFLAG_PASSABLE) == 0 || + const struct fileops *ops; + + ops = ofde->fde_file->f_ops; + fp = NULL; + if ((ops->fo_flags & DFLAG_FORK) != 0 && + (ofde->fde_flags & UF_FOCLOSE) == 0) { + if (ops->fo_fork(newfdp, ofde->fde_file, &fp, p1, + curthread) != 0) + continue; + fork_pass = true; + } else if ((ops->fo_flags & DFLAG_PASSABLE) == 0 || (ofde->fde_flags & UF_FOCLOSE) != 0 || !fhold(ofde->fde_file)) { if (newfdp->fd_freefile == fdp->fd_freefile) @@ -2536,11 +2564,30 @@ fdcopy(struct filedesc *fdp) } nfde = &newfdp->fd_ofiles[i]; *nfde = *ofde; + if (fp != NULL) + nfde->fde_file = fp; filecaps_copy(&ofde->fde_caps, &nfde->fde_caps, true); fdused_init(newfdp, i); } MPASS(newfdp->fd_freefile != -1); FILEDESC_SUNLOCK(fdp); + + /* + * Now handle copying kqueues, since all fds, including + * kqueues, are in place. + */ + if (__predict_false(fork_pass)) { + FILEDESC_FOREACH_FDE(newfdp, i, nfde) { + const struct fileops *ops; + + ops = nfde->fde_file->f_ops; + if ((ops->fo_flags & DFLAG_FORK) == 0 || + nfde->fde_file == NULL) + continue; + ops->fo_fork(newfdp, NULL, &nfde->fde_file, p1, + curthread); + } + } return (newfdp); } diff --git a/sys/sys/file.h b/sys/sys/file.h index 9a072121e25f..b2bd62f244da 100644 --- a/sys/sys/file.h +++ b/sys/sys/file.h @@ -137,6 +137,8 @@ typedef int fo_fspacectl_t(struct file *fp, int cmd, off_t *offset, off_t *length, int flags, struct ucred *active_cred, struct thread *td); typedef int fo_cmp_t(struct file *fp, struct file *fp1, struct thread *td); +typedef int fo_fork_t(struct filedesc *fdp, struct file *fp, struct file **fp1, + struct proc *p1, struct thread *td); typedef int fo_spare_t(struct file *fp); typedef int fo_flags_t; @@ -161,12 +163,14 @@ struct fileops { fo_fallocate_t *fo_fallocate; fo_fspacectl_t *fo_fspacectl; fo_cmp_t *fo_cmp; - fo_spare_t *fo_spares[8]; /* Spare slots */ + fo_fork_t *fo_fork; + fo_spare_t *fo_spares[7]; /* Spare slots */ fo_flags_t fo_flags; /* DFLAG_* below */ }; #define DFLAG_PASSABLE 0x01 /* may be passed via unix sockets. */ #define DFLAG_SEEKABLE 0x02 /* seekable / nonsequential */ +#define DFLAG_FORK 0x04 /* copy on fork */ #endif /* _KERNEL */ #if defined(_KERNEL) || defined(_WANT_FILE)
