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Diffstat (limited to 'Documentation/filesystems/tmpfs.rst')
| -rw-r--r-- | Documentation/filesystems/tmpfs.rst | 38 |
1 files changed, 36 insertions, 2 deletions
diff --git a/Documentation/filesystems/tmpfs.rst b/Documentation/filesystems/tmpfs.rst index 2cd8fa332feb..56a26c843dbe 100644 --- a/Documentation/filesystems/tmpfs.rst +++ b/Documentation/filesystems/tmpfs.rst @@ -21,8 +21,8 @@ explained further below, some of which can be reconfigured dynamically on the fly using a remount ('mount -o remount ...') of the filesystem. A tmpfs filesystem can be resized but it cannot be resized to a size below its current usage. tmpfs also supports POSIX ACLs, and extended attributes for the -trusted.* and security.* namespaces. ramfs does not use swap and you cannot -modify any parameter for a ramfs filesystem. The size limit of a ramfs +trusted.*, security.* and user.* namespaces. ramfs does not use swap and you +cannot modify any parameter for a ramfs filesystem. The size limit of a ramfs filesystem is how much memory you have available, and so care must be taken if used so to not run out of memory. @@ -97,6 +97,9 @@ mount with such options, since it allows any user with write access to use up all the memory on the machine; but enhances the scalability of that instance in a system with many CPUs making intensive use of it. +If nr_inodes is not 0, that limited space for inodes is also used up by +extended attributes: "df -i"'s IUsed and IUse% increase, IFree decreases. + tmpfs blocks may be swapped out, when there is a shortage of memory. tmpfs has a mount option to disable its use of swap: @@ -123,6 +126,37 @@ sysfs file /sys/kernel/mm/transparent_hugepage/shmem_enabled: which can be used to deny huge pages on all tmpfs mounts in an emergency, or to force huge pages on all tmpfs mounts for testing. +tmpfs also supports quota with the following mount options + +======================== ================================================= +quota User and group quota accounting and enforcement + is enabled on the mount. Tmpfs is using hidden + system quota files that are initialized on mount. +usrquota User quota accounting and enforcement is enabled + on the mount. +grpquota Group quota accounting and enforcement is enabled + on the mount. +usrquota_block_hardlimit Set global user quota block hard limit. +usrquota_inode_hardlimit Set global user quota inode hard limit. +grpquota_block_hardlimit Set global group quota block hard limit. +grpquota_inode_hardlimit Set global group quota inode hard limit. +======================== ================================================= + +None of the quota related mount options can be set or changed on remount. + +Quota limit parameters accept a suffix k, m or g for kilo, mega and giga +and can't be changed on remount. Default global quota limits are taking +effect for any and all user/group/project except root the first time the +quota entry for user/group/project id is being accessed - typically the +first time an inode with a particular id ownership is being created after +the mount. In other words, instead of the limits being initialized to zero, +they are initialized with the particular value provided with these mount +options. The limits can be changed for any user/group id at any time as they +normally can be. + +Note that tmpfs quotas do not support user namespaces so no uid/gid +translation is done if quotas are enabled inside user namespaces. + tmpfs has a mount option to set the NUMA memory allocation policy for all files in that instance (if CONFIG_NUMA is enabled) - which can be adjusted on the fly via 'mount -o remount ...' |