Author: kevans Date: Tue Sep 3 20:33:38 2019 New Revision: 351796 URL: https://svnweb.freebsd.org/changeset/base/351796
Log: posixshm: start counting writeable mappings r351650 switched posixshm to using OBJT_SWAP for shm_object r351795 added support to the swap_pager for tracking writeable mappings Take advantage of this and start tracking writeable mappings; fd sealing will use this to reject a seal on writing with EBUSY if any such mapping exist. Reviewed by: kib, markj Differential Revision: https://reviews.freebsd.org/D21456 Modified: head/sys/kern/uipc_shm.c Modified: head/sys/kern/uipc_shm.c ============================================================================== --- head/sys/kern/uipc_shm.c Tue Sep 3 20:31:48 2019 (r351795) +++ head/sys/kern/uipc_shm.c Tue Sep 3 20:33:38 2019 (r351796) @@ -895,6 +895,7 @@ shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *a struct shmfd *shmfd; vm_prot_t maxprot; int error; + bool writecnt; shmfd = fp->f_data; maxprot = VM_PROT_NONE; @@ -905,10 +906,10 @@ shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *a if ((fp->f_flag & FWRITE) != 0) maxprot |= VM_PROT_WRITE; + writecnt = (flags & MAP_SHARED) != 0 && (prot & VM_PROT_WRITE) != 0; + /* Don't permit shared writable mappings on read-only descriptors. */ - if ((flags & MAP_SHARED) != 0 && - (maxprot & VM_PROT_WRITE) == 0 && - (prot & VM_PROT_WRITE) != 0) + if (writecnt && (maxprot & VM_PROT_WRITE) == 0) return (EACCES); maxprot &= cap_maxprot; @@ -931,10 +932,16 @@ shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *a mtx_unlock(&shm_timestamp_lock); vm_object_reference(shmfd->shm_object); + if (writecnt) + vm_pager_update_writecount(shmfd->shm_object, 0, objsize); error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, - shmfd->shm_object, foff, FALSE, td); - if (error != 0) + shmfd->shm_object, foff, writecnt, td); + if (error != 0) { + if (writecnt) + vm_pager_release_writecount(shmfd->shm_object, 0, + objsize); vm_object_deallocate(shmfd->shm_object); + } return (error); } _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
