Re: [PATCH 5/5] block: enable dax for raw block devices

On Tue, Oct 27, 2015 at 09:19:30AM +1100, Dave Chinner wrote: > On Mon, Oct 26, 2015 at 05:56:30PM +0900, Dan Williams wrote: > > On Mon, Oct 26, 2015 at 3:23 PM, Dave Chinner wrote: > > > Also, DAX access isn't a property of mmap - it's a property > > > of the inode. We cannot do DAX access via

Re: [PATCH 5/5] block: enable dax for raw block devices

On Tue, Oct 27, 2015 at 09:19:30AM +1100, Dave Chinner wrote: > On Mon, Oct 26, 2015 at 05:56:30PM +0900, Dan Williams wrote: > > On Mon, Oct 26, 2015 at 3:23 PM, Dave Chinner wrote: > > > Also, DAX access isn't a property of mmap - it's a property > > > of the inode. We

Re: [PATCH 5/5] block: enable dax for raw block devices

On Mon, Oct 26, 2015 at 05:56:30PM +0900, Dan Williams wrote: > On Mon, Oct 26, 2015 at 3:23 PM, Dave Chinner wrote: > > Also, DAX access isn't a property of mmap - it's a property > > of the inode. We cannot do DAX access via mmap while mixing page > > cache based access through file descriptor

Re: [PATCH 5/5] block: enable dax for raw block devices

On Mon, Oct 26, 2015 at 3:23 PM, Dave Chinner wrote: > On Mon, Oct 26, 2015 at 11:48:06AM +0900, Dan Williams wrote: >> On Mon, Oct 26, 2015 at 6:22 AM, Dave Chinner wrote: >> > On Thu, Oct 22, 2015 at 11:08:18PM +0200, Jan Kara wrote: >> >> Ugh2: Now I realized that DAX mmap isn't safe wrt fs

Re: [PATCH 5/5] block: enable dax for raw block devices

On Mon 26-10-15 17:23:19, Dave Chinner wrote: > On Mon, Oct 26, 2015 at 11:48:06AM +0900, Dan Williams wrote: > > 2/ Even if we get a new flag that lets the kernel know the app > > understands DAX mappings, we shouldn't leave fsync broken. Can we > > instead get by with a simple / big hammer

Re: [PATCH 5/5] block: enable dax for raw block devices

On Mon, Oct 26, 2015 at 11:48:06AM +0900, Dan Williams wrote: > On Mon, Oct 26, 2015 at 6:22 AM, Dave Chinner wrote: > > On Thu, Oct 22, 2015 at 11:08:18PM +0200, Jan Kara wrote: > >> Ugh2: Now I realized that DAX mmap isn't safe wrt fs freezing even for > >> filesystems since there's nothing

Re: [PATCH 5/5] block: enable dax for raw block devices

On Mon 26-10-15 17:23:19, Dave Chinner wrote: > On Mon, Oct 26, 2015 at 11:48:06AM +0900, Dan Williams wrote: > > 2/ Even if we get a new flag that lets the kernel know the app > > understands DAX mappings, we shouldn't leave fsync broken. Can we > > instead get by with a simple / big hammer

Re: [PATCH 5/5] block: enable dax for raw block devices

On Mon, Oct 26, 2015 at 3:23 PM, Dave Chinner wrote: > On Mon, Oct 26, 2015 at 11:48:06AM +0900, Dan Williams wrote: >> On Mon, Oct 26, 2015 at 6:22 AM, Dave Chinner wrote: >> > On Thu, Oct 22, 2015 at 11:08:18PM +0200, Jan Kara wrote: >> >> Ugh2: Now I

Re: [PATCH 5/5] block: enable dax for raw block devices

On Mon, Oct 26, 2015 at 11:48:06AM +0900, Dan Williams wrote: > On Mon, Oct 26, 2015 at 6:22 AM, Dave Chinner wrote: > > On Thu, Oct 22, 2015 at 11:08:18PM +0200, Jan Kara wrote: > >> Ugh2: Now I realized that DAX mmap isn't safe wrt fs freezing even for > >> filesystems

Re: [PATCH 5/5] block: enable dax for raw block devices

On Mon, Oct 26, 2015 at 05:56:30PM +0900, Dan Williams wrote: > On Mon, Oct 26, 2015 at 3:23 PM, Dave Chinner wrote: > > Also, DAX access isn't a property of mmap - it's a property > > of the inode. We cannot do DAX access via mmap while mixing page > > cache based access

Re: [PATCH 5/5] block: enable dax for raw block devices

On Mon, Oct 26, 2015 at 6:22 AM, Dave Chinner wrote: > On Thu, Oct 22, 2015 at 11:08:18PM +0200, Jan Kara wrote: >> Ugh2: Now I realized that DAX mmap isn't safe wrt fs freezing even for >> filesystems since there's nothing which writeprotects pages that are >> writeably mapped. In normal path,

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu, Oct 22, 2015 at 11:08:18PM +0200, Jan Kara wrote: > Ugh2: Now I realized that DAX mmap isn't safe wrt fs freezing even for > filesystems since there's nothing which writeprotects pages that are > writeably mapped. In normal path, page writeback does this but that doesn't > happen for DAX.

Re: [PATCH 5/5] block: enable dax for raw block devices

On Mon, Oct 26, 2015 at 6:22 AM, Dave Chinner wrote: > On Thu, Oct 22, 2015 at 11:08:18PM +0200, Jan Kara wrote: >> Ugh2: Now I realized that DAX mmap isn't safe wrt fs freezing even for >> filesystems since there's nothing which writeprotects pages that are >> writeably

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu, Oct 22, 2015 at 11:08:18PM +0200, Jan Kara wrote: > Ugh2: Now I realized that DAX mmap isn't safe wrt fs freezing even for > filesystems since there's nothing which writeprotects pages that are > writeably mapped. In normal path, page writeback does this but that doesn't > happen for DAX.

Re: [PATCH 5/5] block: enable dax for raw block devices

On Fri 23-10-15 16:32:57, Dan Williams wrote: > On Thu, Oct 22, 2015 at 2:08 PM, Jan Kara wrote: > > On Thu 22-10-15 16:05:46, Williams, Dan J wrote: > [..] > >> This text was aimed at the request from Ross to document the differences > >> vs the generic_file_mmap() path. Is the following

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu 22-10-15 23:41:27, Williams, Dan J wrote: > On Thu, 2015-10-22 at 23:08 +0200, Jan Kara wrote: > > On Thu 22-10-15 16:05:46, Williams, Dan J wrote: > > > On Thu, 2015-10-22 at 11:35 +0200, Jan Kara wrote: > > > > On Thu 22-10-15 02:42:11, Dan Williams wrote: > > > > > If an application

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu 22-10-15 23:41:27, Williams, Dan J wrote: > On Thu, 2015-10-22 at 23:08 +0200, Jan Kara wrote: > > On Thu 22-10-15 16:05:46, Williams, Dan J wrote: > > > On Thu, 2015-10-22 at 11:35 +0200, Jan Kara wrote: > > > > On Thu 22-10-15 02:42:11, Dan Williams wrote: > > > > > If an application

Re: [PATCH 5/5] block: enable dax for raw block devices

On Fri 23-10-15 16:32:57, Dan Williams wrote: > On Thu, Oct 22, 2015 at 2:08 PM, Jan Kara wrote: > > On Thu 22-10-15 16:05:46, Williams, Dan J wrote: > [..] > >> This text was aimed at the request from Ross to document the differences > >> vs the generic_file_mmap() path. Is the

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu, Oct 22, 2015 at 2:08 PM, Jan Kara wrote: > On Thu 22-10-15 16:05:46, Williams, Dan J wrote: [..] >> This text was aimed at the request from Ross to document the differences >> vs the generic_file_mmap() path. Is the following incremental change >> more clear? > > Well, not really. I

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu, Oct 22, 2015 at 2:08 PM, Jan Kara wrote: > On Thu 22-10-15 16:05:46, Williams, Dan J wrote: [..] >> This text was aimed at the request from Ross to document the differences >> vs the generic_file_mmap() path. Is the following incremental change >> more clear? > > Well, not

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu, 2015-10-22 at 23:08 +0200, Jan Kara wrote: > On Thu 22-10-15 16:05:46, Williams, Dan J wrote: > > On Thu, 2015-10-22 at 11:35 +0200, Jan Kara wrote: > > > On Thu 22-10-15 02:42:11, Dan Williams wrote: > > > > If an application wants exclusive access to all of the persistent memory > > > >

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu 22-10-15 16:05:46, Williams, Dan J wrote: > On Thu, 2015-10-22 at 11:35 +0200, Jan Kara wrote: > > On Thu 22-10-15 02:42:11, Dan Williams wrote: > > > If an application wants exclusive access to all of the persistent memory > > > provided by an NVDIMM namespace it can use this raw-block-dax

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu, 2015-10-22 at 11:35 +0200, Jan Kara wrote: > On Thu 22-10-15 02:42:11, Dan Williams wrote: > > If an application wants exclusive access to all of the persistent memory > > provided by an NVDIMM namespace it can use this raw-block-dax facility > > to forgo establishing a filesystem. This

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu 22-10-15 02:42:11, Dan Williams wrote: > If an application wants exclusive access to all of the persistent memory > provided by an NVDIMM namespace it can use this raw-block-dax facility > to forgo establishing a filesystem. This capability is targeted > primarily to hypervisors wanting to

[PATCH 5/5] block: enable dax for raw block devices

If an application wants exclusive access to all of the persistent memory provided by an NVDIMM namespace it can use this raw-block-dax facility to forgo establishing a filesystem. This capability is targeted primarily to hypervisors wanting to provision persistent memory for guests. Cc: Jan Kara

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu 22-10-15 16:05:46, Williams, Dan J wrote: > On Thu, 2015-10-22 at 11:35 +0200, Jan Kara wrote: > > On Thu 22-10-15 02:42:11, Dan Williams wrote: > > > If an application wants exclusive access to all of the persistent memory > > > provided by an NVDIMM namespace it can use this raw-block-dax

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu, 2015-10-22 at 23:08 +0200, Jan Kara wrote: > On Thu 22-10-15 16:05:46, Williams, Dan J wrote: > > On Thu, 2015-10-22 at 11:35 +0200, Jan Kara wrote: > > > On Thu 22-10-15 02:42:11, Dan Williams wrote: > > > > If an application wants exclusive access to all of the persistent memory > > > >

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu 22-10-15 02:42:11, Dan Williams wrote: > If an application wants exclusive access to all of the persistent memory > provided by an NVDIMM namespace it can use this raw-block-dax facility > to forgo establishing a filesystem. This capability is targeted > primarily to hypervisors wanting to

[PATCH 5/5] block: enable dax for raw block devices

If an application wants exclusive access to all of the persistent memory provided by an NVDIMM namespace it can use this raw-block-dax facility to forgo establishing a filesystem. This capability is targeted primarily to hypervisors wanting to provision persistent memory for guests. Cc: Jan Kara

Re: [PATCH 5/5] block: enable dax for raw block devices

On Thu, 2015-10-22 at 11:35 +0200, Jan Kara wrote: > On Thu 22-10-15 02:42:11, Dan Williams wrote: > > If an application wants exclusive access to all of the persistent memory > > provided by an NVDIMM namespace it can use this raw-block-dax facility > > to forgo establishing a filesystem. This