Date: Fri, 31 Jul 2015 10:28:19 -0700 From: John Baldwin <jhb@freebsd.org> To: Oliver Pinter <oliver.pinter@hardenedbsd.org> Cc: "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r283998 - in head/sys: dev/drm dev/drm2 fs/devfs kern sys vm Message-ID: <2301099.YseXhuPoWd@ralph.baldwin.cx> In-Reply-To: <CAPQ4fft0RrG1UKXyp1kvqxD-9BaTFeTYpM5LEGL=yZw7brtk8Q@mail.gmail.com> References: <201506041941.t54JfGAA075455@svn.freebsd.org> <CAPQ4fft0RrG1UKXyp1kvqxD-9BaTFeTYpM5LEGL=yZw7brtk8Q@mail.gmail.com>
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On Thursday, July 30, 2015 09:11:54 PM Oliver Pinter wrote: > Hi John! > > On Thu, Jun 4, 2015 at 9:41 PM, John Baldwin <jhb@freebsd.org> wrote: > > Author: jhb > > Date: Thu Jun 4 19:41:15 2015 > > New Revision: 283998 > > URL: https://svnweb.freebsd.org/changeset/base/283998 > > > > Log: > > Add a new file operations hook for mmap operations. File type-specific > > logic is now placed in the mmap hook implementation rather than requiring > > it to be placed in sys/vm/vm_mmap.c. This hook allows new file types to > > support mmap() as well as potentially allowing mmap() for existing file > > types that do not currently support any mapping. > > > > The vm_mmap() function is now split up into two functions. A new > > vm_mmap_object() function handles the "back half" of vm_mmap() and accepts > > a referenced VM object to map rather than a (handle, handle_type) tuple. > > vm_mmap() is now reduced to converting a (handle, handle_type) tuple to a > > a VM object and then calling vm_mmap_object() to handle the actual mapping. > > The vm_mmap() function remains for use by other parts of the kernel > > (e.g. device drivers and exec) but now only supports mapping vnodes, > > character devices, and anonymous memory. > > > > The mmap() system call invokes vm_mmap_object() directly with a NULL object > > for anonymous mappings. For mappings using a file descriptor, the > > descriptors fo_mmap() hook is invoked instead. The fo_mmap() hook is > > responsible for performing type-specific checks and adjustments to > > arguments as well as possibly modifying mapping parameters such as flags > > or the object offset. The fo_mmap() hook routines then call > > vm_mmap_object() to handle the actual mapping. > > > > The fo_mmap() hook is optional. If it is not set, then fo_mmap() will > > fail with ENODEV. A fo_mmap() hook is implemented for regular files, > > character devices, and shared memory objects (created via shm_open()). > > > > While here, consistently use the VM_PROT_* constants for the vm_prot_t > > type for the 'prot' variable passed to vm_mmap() and vm_mmap_object() > > as well as the vm_mmap_vnode() and vm_mmap_cdev() helper routines. > > Previously some places were using the mmap()-specific PROT_* constants > > instead. While this happens to work because PROT_xx == VM_PROT_xx, > > using VM_PROT_* is more correct. > > > > Differential Revision: https://reviews.freebsd.org/D2658 > > Reviewed by: alc (glanced over), kib > > MFC after: 1 month > > Sponsored by: Chelsio > > > > Modified: > > head/sys/dev/drm/drm_bufs.c > > head/sys/dev/drm2/drm_bufs.c > > head/sys/fs/devfs/devfs_vnops.c > > head/sys/kern/subr_uio.c > > head/sys/kern/uipc_shm.c > > head/sys/kern/vfs_vnops.c > > head/sys/sys/file.h > > head/sys/sys/mman.h > > head/sys/vm/vm_extern.h > > head/sys/vm/vm_mmap.c > > > > > ... patch trimmed... > > When plan you to MFC this change to 10-STABLE? There's a regression reported by sbruno@ that needs to be resolved before it can be merged. I might also need to employ an extra hack to preserve the ABI (e.g. adding a new flag that has to be set in the fileops to say that the fo_mmap field is present like was done for fo_truncate). -- John Baldwin
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