Author: jeff Date: Fri Feb 28 20:33:28 2020 New Revision: 358446 URL: https://svnweb.freebsd.org/changeset/base/358446
Log: Use unlocked grab for uipc_shm/tmpfs. Reviewed by: markj Differential Revision: https://reviews.freebsd.org/D23865 Modified: head/sys/kern/uipc_shm.c Modified: head/sys/kern/uipc_shm.c ============================================================================== --- head/sys/kern/uipc_shm.c Fri Feb 28 20:32:35 2020 (r358445) +++ head/sys/kern/uipc_shm.c Fri Feb 28 20:33:28 2020 (r358446) @@ -176,23 +176,25 @@ uiomove_object_page(vm_object_t obj, size_t len, struc offset = uio->uio_offset & PAGE_MASK; tlen = MIN(PAGE_SIZE - offset, len); - VM_OBJECT_WLOCK(obj); + rv = vm_page_grab_valid_unlocked(&m, obj, idx, + VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT); + if (rv == VM_PAGER_OK) + goto found; /* * Read I/O without either a corresponding resident page or swap * page: use zero_region. This is intended to avoid instantiating * pages on read from a sparse region. */ - if (uio->uio_rw == UIO_READ && vm_page_lookup(obj, idx) == NULL && + VM_OBJECT_WLOCK(obj); + m = vm_page_lookup(obj, idx); + if (uio->uio_rw == UIO_READ && m == NULL && !vm_pager_has_page(obj, idx, NULL, NULL)) { VM_OBJECT_WUNLOCK(obj); return (uiomove(__DECONST(void *, zero_region), tlen, uio)); } /* - * Parallel reads of the page content from disk are prevented - * by exclusive busy. - * * Although the tmpfs vnode lock is held here, it is * nonetheless safe to sleep waiting for a free page. The * pageout daemon does not need to acquire the tmpfs vnode @@ -208,6 +210,8 @@ uiomove_object_page(vm_object_t obj, size_t len, struc return (EIO); } VM_OBJECT_WUNLOCK(obj); + +found: error = uiomove_fromphys(&m, offset, tlen, uio); if (uio->uio_rw == UIO_WRITE && error == 0) vm_page_set_dirty(m); _______________________________________________ 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"
