diff options
| author | Chris Down <chris@chrisdown.name> | 2020-08-06 23:20:25 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-07 11:33:24 -0700 |
| commit | ea3271f7196c65ae5d3e1c7b3f733892c017dbd6 (patch) | |
| tree | b8e35df0da0afea4a25cfdaf2ceaf07d7db30f62 /Documentation/filesystems | |
| parent | e809d5f0b5c912fe981dce738f3283b2010665f0 (diff) | |
tmpfs: support 64-bit inums per-sb
The default is still set to inode32 for backwards compatibility, but
system administrators can opt in to the new 64-bit inode numbers by
either:
1. Passing inode64 on the command line when mounting, or
2. Configuring the kernel with CONFIG_TMPFS_INODE64=y
The inode64 and inode32 names are used based on existing precedent from
XFS.
[hughd@google.com: Kconfig fixes]
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008011928010.13320@eggly.anvils
Signed-off-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/8b23758d0c66b5e2263e08baf9c4b6a7565cbd8f.1594661218.git.chris@chrisdown.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/tmpfs.rst | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/filesystems/tmpfs.rst b/Documentation/filesystems/tmpfs.rst index 4e95929301a5..c44f8b1d3cab 100644 --- a/Documentation/filesystems/tmpfs.rst +++ b/Documentation/filesystems/tmpfs.rst @@ -150,6 +150,22 @@ These options do not have any effect on remount. You can change these parameters with chmod(1), chown(1) and chgrp(1) on a mounted filesystem. +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. + + 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 RAM/SWAP in 10240 inodes and it is only accessible by root. @@ -161,3 +177,5 @@ RAM/SWAP in 10240 inodes and it is only accessible by root. Hugh Dickins, 4 June 2007 :Updated: KOSAKI Motohiro, 16 Mar 2010 +:Updated: + Chris Down, 13 July 2020 |