[git pull] common helper for kmap_local_page() users in local filesystems

[git pull] common helper for kmap_local_page() users in local filesystems

[Al Viro]

	kmap_local_page() conversions in local filesystems keep running into
kunmap_local_page()+put_page() combinations; we can keep inventing names
for identical inline helpers, but it's getting rather inconvenient.  I've added
a trivial helper to linux/highmem.h instead.

	I would've held that back until the merge window, if not for the
mess it causes in tree topology - I've several branches merging from that
one, and it's only going to get worse if e.g. ext2 stuff gets picked by
Jan.

	The helper is trivial and it's early in the cycle.  It would simplify
the things if you could pull it - then I'd simply rebase the affected branches
to -rc2...

The following changes since commit fe15c26ee26efa11741a7b632e9f23b01aca4cc6:

  Linux 6.3-rc1 (2023-03-05 14:52:03 -0800)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git tags/pull-highmem

for you to fetch changes up to 849ad04cf562ac63b0371a825eed473d84de9c6d:

  new helper: put_and_unmap_page() (2023-03-07 01:50:53 -0500)

----------------------------------------------------------------
put_and_unmap_page() helper

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

----------------------------------------------------------------
Al Viro (1):
      new helper: put_and_unmap_page()

 include/linux/highmem.h | 6 ++++++
 1 file changed, 6 insertions(+)

Re: [git pull] common helper for kmap_local_page() users in local filesystems

[pr-tracker-bot]

The pull request you sent on Fri, 10 Mar 2023 20:44:31 +0000:

> git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git tags/pull-highmem

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/d33d4c9e0888e9ee7666813b3f9ecc244a64d127

Thank you!

-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/prtracker.html

Re: [git pull] common helper for kmap_local_page() users in local filesystems

[Fabio M. De Francesco]

On venerdì 10 marzo 2023 21:44:31 CET Al Viro wrote:
> 	kmap_local_page() conversions in local filesystems keep running into
> kunmap_local_page()+put_page() combinations; we can keep inventing names
> for identical inline helpers, but it's getting rather inconvenient.  I've
> added a trivial helper to linux/highmem.h instead.

Yeah, "put_and_unmap_page()". Nice helper :-)

Today I decided to prepare a series to convert all the functions of all the 
filesystems where I had found the above-mentioned pattern but I stopped 
immediately after converting dir_put_page() in fs/sysv.

Why? Just because I realized that I do not understand the reasons behind the 
choice of the name of the helper...  

Why did you name it "put_and_unmap_page()" instead of "unmap_and_put_page()", 
for we always unmap first _and_ put the page immediately the unmapping?

It seems it want to imply that instead we put first and unmap later (which 
would be wrong). That name sounds misleading to me and not sound (logically 
speaking).

Am I missing some obscure convention behind your choice of that name for the 
helper?

If not, can you please change it from "put_and_unmap_page()" to 
"unmap_and_put_page()"? 

Thanks,

Fabio

> 
> 	I would've held that back until the merge window, if not for the
> mess it causes in tree topology - I've several branches merging from that
> one, and it's only going to get worse if e.g. ext2 stuff gets picked by
> Jan.
> 
> 	The helper is trivial and it's early in the cycle.  It would 
simplify
> the things if you could pull it - then I'd simply rebase the affected 
branches
> to -rc2...
> 
> The following changes since commit fe15c26ee26efa11741a7b632e9f23b01aca4cc6:
> 
>   Linux 6.3-rc1 (2023-03-05 14:52:03 -0800)
> 
> are available in the Git repository at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git tags/pull-
highmem
> 
> for you to fetch changes up to 849ad04cf562ac63b0371a825eed473d84de9c6d:
> 
>   new helper: put_and_unmap_page() (2023-03-07 01:50:53 -0500)
> 
> ----------------------------------------------------------------
> put_and_unmap_page() helper
> 
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> 
> ----------------------------------------------------------------
> Al Viro (1):
>       new helper: put_and_unmap_page()
> 
>  include/linux/highmem.h | 6 ++++++
>  1 file changed, 6 insertions(+)

Re: [git pull] common helper for kmap_local_page() users in local filesystems

[Fabio M. De Francesco]

On sabato 11 marzo 2023 18:11:01 CEST Fabio M. De Francesco wrote:
> On venerdì 10 marzo 2023 21:44:31 CET Al Viro wrote:
> > 	kmap_local_page() conversions in local filesystems keep running into
> > 
> > kunmap_local_page()+put_page() combinations; we can keep inventing names
> > for identical inline helpers, but it's getting rather inconvenient.  I've
> > added a trivial helper to linux/highmem.h instead.
> 
> Yeah, "put_and_unmap_page()". Nice helper :-)

[snip]

Hi Al, 

> Why did you name it "put_and_unmap_page()" instead of 
"unmap_and_put_page()",
> for we always unmap first _and_ put the page immediately the unmapping?
>
> It seems it want to imply that instead we put first and unmap later (which
> would be wrong). That name sounds misleading to me and not sound (logically
> speaking).
> 
> Am I missing some obscure convention behind your choice of that name for the
> helper?

Can you please explain what I'm missing behind your motivation?

Thanks,

Fabio

P.S.: Adding Ira to the Cc list, since he's been doing kmap() and 
kmap_atomic() conversions long time before I too started with them.