| Message ID | alpine.LSU.2.11.2008011928010.13320@eggly.anvils (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [mmotm] tmpfs: support 64-bit inums per-sb fix | expand |
On 8/1/20 7:37 PM, Hugh Dickins wrote: > Expanded Chris's Documentation and Kconfig help on tmpfs inode64. > TMPFS_INODE64 still there, still default N, but writing down its very > limited limitation does make me wonder again if we want the option. > > Signed-off-by: Hugh Dickins <hughd@google.com> > --- > Andrew, please fold into tmpfs-support-64-bit-inums-per-sb.patch later. > > Randy, you're very active on Documentation and linux-next: may I ask you > please to try applying this patch to latest, and see if tmpfs.rst comes > out looking right to you? I'm an old dog still stuck in the days of Hi Hugh, It looks fine. > tmpfs.txt, hoping to avoid new tricks for a while. Thanks! (Bonus > points if you can explain what the "::" on line 122 is about. I started > out reading Documentation/doc-guide/sphinx.rst, but... got diverted. > Perhaps I should ask Mauro or Jon, but turning for help first to you.) That's the correct file. Around line 216, it says: * For inserting fixed width text blocks (for code examples, use case examples, etc.), use ``::`` for anything that doesn't really benefit from syntax highlighting, especially short snippets. Use ``.. code-block:: <language>`` for longer code blocks that benefit from highlighting. For a short snippet of code embedded in the text, use \`\`. so it's just for a (short) code example block, fixed font... > > Documentation/filesystems/tmpfs.rst | 13 ++++++++++--- > fs/Kconfig | 16 +++++++++++----- > 2 files changed, 21 insertions(+), 8 deletions(-) > > --- mmotm/Documentation/filesystems/tmpfs.rst 2020-07-27 18:54:51.116524795 -0700 > +++ linux/Documentation/filesystems/tmpfs.rst 2020-08-01 18:37:07.719713987 -0700 cheers.
On Sat, 1 Aug 2020, Randy Dunlap wrote: > On 8/1/20 7:37 PM, Hugh Dickins wrote: > > Expanded Chris's Documentation and Kconfig help on tmpfs inode64. > > TMPFS_INODE64 still there, still default N, but writing down its very > > limited limitation does make me wonder again if we want the option. > > > > Signed-off-by: Hugh Dickins <hughd@google.com> > > --- > > Andrew, please fold into tmpfs-support-64-bit-inums-per-sb.patch later. > > > > Randy, you're very active on Documentation and linux-next: may I ask you > > please to try applying this patch to latest, and see if tmpfs.rst comes > > out looking right to you? I'm an old dog still stuck in the days of > > Hi Hugh, > It looks fine. Thank you so much, Randy. > > > tmpfs.txt, hoping to avoid new tricks for a while. Thanks! (Bonus > > points if you can explain what the "::" on line 122 is about. I started > > out reading Documentation/doc-guide/sphinx.rst, but... got diverted. > > Perhaps I should ask Mauro or Jon, but turning for help first to you.) > > That's the correct file. Around line 216, it says: > > * For inserting fixed width text blocks (for code examples, use case > examples, etc.), use ``::`` for anything that doesn't really benefit > from syntax highlighting, especially short snippets. Use > ``.. code-block:: <language>`` for longer code blocks that benefit > from highlighting. For a short snippet of code embedded in the text, use \`\`. > > > so it's just for a (short) code example block, fixed font... Bonus points awarded, thanks...ish. I'll have to look around for more examples of where that's done, and I think it'll only make real sense to me, when I'm further along, producing the proper output, then seeing how bad something looks without the "::". Thanks again, Hugh
--- mmotm/Documentation/filesystems/tmpfs.rst 2020-07-27 18:54:51.116524795 -0700 +++ linux/Documentation/filesystems/tmpfs.rst 2020-08-01 18:37:07.719713987 -0700 @@ -153,11 +153,18 @@ parameters with chmod(1), chown(1) and c tmpfs has a mount option to select whether it will wrap at 32- or 64-bit inode numbers: +======= ======================== inode64 Use 64-bit inode numbers inode32 Use 32-bit inode numbers +======= ======================== + +On a 32-bit kernel, inode32 is implicit, and inode64 is refused at mount time. +On a 64-bit kernel, CONFIG_TMPFS_INODE64 sets the default. inode64 avoids the +possibility of multiple files with the same inode number on a single device; +but risks glibc failing with EOVERFLOW once 33-bit inode numbers are reached - +if a long-lived tmpfs is accessed by 32-bit applications so ancient that +opening a file larger than 2GiB fails with EINVAL. -On 64-bit, the default is set by CONFIG_TMPFS_INODE64. On 32-bit, inode64 is -not legal and will produce an error at mount time. So 'mount -t tmpfs -o size=10G,nr_inodes=10k,mode=700 tmpfs /mytmpfs' will give you tmpfs instance on /mytmpfs which can allocate 10GB @@ -170,5 +177,5 @@ RAM/SWAP in 10240 inodes and it is only Hugh Dickins, 4 June 2007 :Updated: KOSAKI Motohiro, 16 Mar 2010 -Updated: +:Updated: Chris Down, 13 July 2020 --- mmotm/fs/Kconfig 2020-07-27 18:54:59.384550639 -0700 +++ linux/fs/Kconfig 2020-08-01 18:11:33.749236321 -0700 @@ -223,12 +223,18 @@ config TMPFS_INODE64 default n help tmpfs has historically used only inode numbers as wide as an unsigned - int. In some cases this can cause wraparound, potentially resulting in - multiple files with the same inode number on a single device. This option - makes tmpfs use the full width of ino_t by default, similarly to the - inode64 mount option. + int. In some cases this can cause wraparound, potentially resulting + in multiple files with the same inode number on a single device. This + option makes tmpfs use the full width of ino_t by default, without + needing to specify the inode64 option when mounting. - To override this default, use the inode32 or inode64 mount options. + But if a long-lived tmpfs is to be accessed by 32-bit applications so + ancient that opening a file larger than 2GiB fails with EINVAL, then + the INODE64 config option and inode64 mount option risk operations + failing with EOVERFLOW once 33-bit inode numbers are reached. + + To override this configured default, use the inode32 or inode64 + option when mounting. If unsure, say N.
Expanded Chris's Documentation and Kconfig help on tmpfs inode64. TMPFS_INODE64 still there, still default N, but writing down its very limited limitation does make me wonder again if we want the option. Signed-off-by: Hugh Dickins <hughd@google.com> --- Andrew, please fold into tmpfs-support-64-bit-inums-per-sb.patch later. Randy, you're very active on Documentation and linux-next: may I ask you please to try applying this patch to latest, and see if tmpfs.rst comes out looking right to you? I'm an old dog still stuck in the days of tmpfs.txt, hoping to avoid new tricks for a while. Thanks! (Bonus points if you can explain what the "::" on line 122 is about. I started out reading Documentation/doc-guide/sphinx.rst, but... got diverted. Perhaps I should ask Mauro or Jon, but turning for help first to you.) Documentation/filesystems/tmpfs.rst | 13 ++++++++++--- fs/Kconfig | 16 +++++++++++----- 2 files changed, 21 insertions(+), 8 deletions(-)