diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/btrfs.txt | 261 | ||||
| -rw-r--r-- | Documentation/filesystems/configfs/configfs.txt | 11 | ||||
| -rw-r--r-- | Documentation/filesystems/devpts.txt | 9 | ||||
| -rw-r--r-- | Documentation/filesystems/nfs/fault_injection.txt | 4 | ||||
| -rw-r--r-- | Documentation/filesystems/nfs/nfs-rdma.txt | 2 | ||||
| -rw-r--r-- | Documentation/filesystems/nfs/nfsroot.txt | 2 | ||||
| -rw-r--r-- | Documentation/filesystems/nfs/pnfs.txt | 6 | ||||
| -rw-r--r-- | Documentation/filesystems/nfs/rpc-server-gss.txt | 2 | ||||
| -rw-r--r-- | Documentation/filesystems/proc.txt | 18 | ||||
| -rw-r--r-- | Documentation/filesystems/sharedsubtree.txt | 8 |
10 files changed, 56 insertions, 267 deletions
diff --git a/Documentation/filesystems/btrfs.txt b/Documentation/filesystems/btrfs.txt index c772b47e7ef0..f9dad22d95ce 100644 --- a/Documentation/filesystems/btrfs.txt +++ b/Documentation/filesystems/btrfs.txt @@ -1,20 +1,10 @@ - BTRFS ===== -Btrfs is a copy on write filesystem for Linux aimed at -implementing advanced features while focusing on fault tolerance, -repair and easy administration. Initially developed by Oracle, Btrfs -is licensed under the GPL and open for contribution from anyone. - -Linux has a wealth of filesystems to choose from, but we are facing a -number of challenges with scaling to the large storage subsystems that -are becoming common in today's data centers. Filesystems need to scale -in their ability to address and manage large storage, and also in -their ability to detect, repair and tolerate errors in the data stored -on disk. Btrfs is under heavy development, and is not suitable for -any uses other than benchmarking and review. The Btrfs disk format is -not yet finalized. +Btrfs is a copy on write filesystem for Linux aimed at implementing advanced +features while focusing on fault tolerance, repair and easy administration. +Jointly developed by several companies, licensed under the GPL and open for +contribution from anyone. The main Btrfs features include: @@ -28,243 +18,14 @@ The main Btrfs features include: * Checksums on data and metadata (multiple algorithms available) * Compression * Integrated multiple device support, with several raid algorithms - * Online filesystem check (not yet implemented) - * Very fast offline filesystem check - * Efficient incremental backup and FS mirroring (not yet implemented) + * Offline filesystem check + * Efficient incremental backup and FS mirroring * Online filesystem defragmentation +For more information please refer to the wiki -Mount Options -============= - -When mounting a btrfs filesystem, the following option are accepted. -Options with (*) are default options and will not show in the mount options. - - alloc_start=<bytes> - Debugging option to force all block allocations above a certain - byte threshold on each block device. The value is specified in - bytes, optionally with a K, M, or G suffix, case insensitive. - Default is 1MB. - - noautodefrag(*) - autodefrag - Disable/enable auto defragmentation. - Auto defragmentation detects small random writes into files and queue - them up for the defrag process. Works best for small files; - Not well suited for large database workloads. - - check_int - check_int_data - check_int_print_mask=<value> - These debugging options control the behavior of the integrity checking - module (the BTRFS_FS_CHECK_INTEGRITY config option required). - - check_int enables the integrity checker module, which examines all - block write requests to ensure on-disk consistency, at a large - memory and CPU cost. - - check_int_data includes extent data in the integrity checks, and - implies the check_int option. - - check_int_print_mask takes a bitmask of BTRFSIC_PRINT_MASK_* values - as defined in fs/btrfs/check-integrity.c, to control the integrity - checker module behavior. - - See comments at the top of fs/btrfs/check-integrity.c for more info. - - commit=<seconds> - Set the interval of periodic commit, 30 seconds by default. Higher - values defer data being synced to permanent storage with obvious - consequences when the system crashes. The upper bound is not forced, - but a warning is printed if it's more than 300 seconds (5 minutes). - - compress - compress=<type> - compress-force - compress-force=<type> - Control BTRFS file data compression. Type may be specified as "zlib" - "lzo" or "no" (for no compression, used for remounting). If no type - is specified, zlib is used. If compress-force is specified, - all files will be compressed, whether or not they compress well. - If compression is enabled, nodatacow and nodatasum are disabled. - - degraded - Allow mounts to continue with missing devices. A read-write mount may - fail with too many devices missing, for example if a stripe member - is completely missing. - - device=<devicepath> - Specify a device during mount so that ioctls on the control device - can be avoided. Especially useful when trying to mount a multi-device - setup as root. May be specified multiple times for multiple devices. - - nodiscard(*) - discard - Disable/enable discard mount option. - Discard issues frequent commands to let the block device reclaim space - freed by the filesystem. - This is useful for SSD devices, thinly provisioned - LUNs and virtual machine images, but may have a significant - performance impact. (The fstrim command is also available to - initiate batch trims from userspace). - - noenospc_debug(*) - enospc_debug - Disable/enable debugging option to be more verbose in some ENOSPC conditions. - - fatal_errors=<action> - Action to take when encountering a fatal error: - "bug" - BUG() on a fatal error. This is the default. - "panic" - panic() on a fatal error. - - noflushoncommit(*) - flushoncommit - The 'flushoncommit' mount option forces any data dirtied by a write in a - prior transaction to commit as part of the current commit. This makes - the committed state a fully consistent view of the file system from the - application's perspective (i.e., it includes all completed file system - operations). This was previously the behavior only when a snapshot is - created. - - inode_cache - Enable free inode number caching. Defaults to off due to an overflow - problem when the free space crcs don't fit inside a single page. - - max_inline=<bytes> - Specify the maximum amount of space, in bytes, that can be inlined in - a metadata B-tree leaf. The value is specified in bytes, optionally - with a K, M, or G suffix, case insensitive. In practice, this value - is limited by the root sector size, with some space unavailable due - to leaf headers. For a 4k sector size, max inline data is ~3900 bytes. - - metadata_ratio=<value> - Specify that 1 metadata chunk should be allocated after every <value> - data chunks. Off by default. - - acl(*) - noacl - Enable/disable support for Posix Access Control Lists (ACLs). See the - acl(5) manual page for more information about ACLs. - - barrier(*) - nobarrier - Enable/disable the use of block layer write barriers. Write barriers - ensure that certain IOs make it through the device cache and are on - persistent storage. If disabled on a device with a volatile - (non-battery-backed) write-back cache, nobarrier option will lead to - filesystem corruption on a system crash or power loss. - - datacow(*) - nodatacow - Enable/disable data copy-on-write for newly created files. - Nodatacow implies nodatasum, and disables all compression. - - datasum(*) - nodatasum - Enable/disable data checksumming for newly created files. - Datasum implies datacow. - - treelog(*) - notreelog - Enable/disable the tree logging used for fsync and O_SYNC writes. - - recovery - Enable autorecovery attempts if a bad tree root is found at mount time. - Currently this scans a list of several previous tree roots and tries to - use the first readable. - - rescan_uuid_tree - Force check and rebuild procedure of the UUID tree. This should not - normally be needed. - - skip_balance - Skip automatic resume of interrupted balance operation after mount. - May be resumed with "btrfs balance resume." - - space_cache (*) - Enable the on-disk freespace cache. - nospace_cache - Disable freespace cache loading without clearing the cache. - clear_cache - Force clearing and rebuilding of the disk space cache if something - has gone wrong. - - ssd - nossd - ssd_spread - Options to control ssd allocation schemes. By default, BTRFS will - enable or disable ssd allocation heuristics depending on whether a - rotational or non-rotational disk is in use. The ssd and nossd options - can override this autodetection. - - The ssd_spread mount option attempts to allocate into big chunks - of unused space, and may perform better on low-end ssds. ssd_spread - implies ssd, enabling all other ssd heuristics as well. - - subvol=<path> - Mount subvolume at <path> rather than the root subvolume. <path> is - relative to the top level subvolume. - - subvolid=<ID> - Mount subvolume specified by an ID number rather than the root subvolume. - This allows mounting of subvolumes which are not in the root of the mounted - filesystem. - You can use "btrfs subvolume list" to see subvolume ID numbers. - - subvolrootid=<objectid> (deprecated) - Mount subvolume specified by <objectid> rather than the root subvolume. - This allows mounting of subvolumes which are not in the root of the mounted - filesystem. - You can use "btrfs subvolume show " to see the object ID for a subvolume. - - thread_pool=<number> - The number of worker threads to allocate. The default number is equal - to the number of CPUs + 2, or 8, whichever is smaller. - - user_subvol_rm_allowed - Allow subvolumes to be deleted by a non-root user. Use with caution. - -MAILING LIST -============ - -There is a Btrfs mailing list hosted on vger.kernel.org. You can -find details on how to subscribe here: - -http://vger.kernel.org/vger-lists.html#linux-btrfs - -Mailing list archives are available from gmane: - -http://dir.gmane.org/gmane.comp.file-systems.btrfs - - - -IRC -=== - -Discussion of Btrfs also occurs on the #btrfs channel of the Freenode -IRC network. - - - - UTILITIES - ========= - -Userspace tools for creating and manipulating Btrfs file systems are -available from the git repository at the following location: - - http://git.kernel.org/?p=linux/kernel/git/mason/btrfs-progs.git - git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs.git - -These include the following tools: - -* mkfs.btrfs: create a filesystem - -* btrfs: a single tool to manage the filesystems, refer to the manpage for more details - -* 'btrfsck' or 'btrfs check': do a consistency check of the filesystem - -Other tools for specific tasks: - -* btrfs-convert: in-place conversion from ext2/3/4 filesystems + https://btrfs.wiki.kernel.org -* btrfs-image: dump filesystem metadata for debugging +that maintains information about administration tasks, frequently asked +questions, use cases, mount options, comprehensible changelogs, features, +manual pages, source code repositories, contacts etc. diff --git a/Documentation/filesystems/configfs/configfs.txt b/Documentation/filesystems/configfs/configfs.txt index e5fe521eea1d..8ec9136aae56 100644 --- a/Documentation/filesystems/configfs/configfs.txt +++ b/Documentation/filesystems/configfs/configfs.txt @@ -250,7 +250,8 @@ child item. struct config_item cg_item; struct list_head cg_children; struct configfs_subsystem *cg_subsys; - struct config_group **default_groups; + struct list_head default_groups; + struct list_head group_entry; }; void config_group_init(struct config_group *group); @@ -420,15 +421,15 @@ These automatic subgroups, or default groups, do not preclude other children of the parent group. If ct_group_ops->make_group() exists, other child groups can be created on the parent group directly. -A configfs subsystem specifies default groups by filling in the -NULL-terminated array default_groups on the config_group structure. -Each group in that array is populated in the configfs tree at the same +A configfs subsystem specifies default groups by adding them using the +configfs_add_default_group() function to the parent config_group +structure. Each added group is populated in the configfs tree at the same time as the parent group. Similarly, they are removed at the same time as the parent. No extra notification is provided. When a ->drop_item() method call notifies the subsystem the parent group is going away, it also means every default group child associated with that parent group. -As a consequence of this, default_groups cannot be removed directly via +As a consequence of this, default groups cannot be removed directly via rmdir(2). They also are not considered when rmdir(2) on the parent group is checking for children. diff --git a/Documentation/filesystems/devpts.txt b/Documentation/filesystems/devpts.txt index 68dffd87f9b7..30d2fcb32f72 100644 --- a/Documentation/filesystems/devpts.txt +++ b/Documentation/filesystems/devpts.txt @@ -51,6 +51,15 @@ where 'ns_exec -cm /bin/bash' calls clone() with CLONE_NEWNS flag and execs /bin/bash in the child process. A pty created by the sshd is not visible in the original mount of /dev/pts. +Total count of pty pairs in all instances is limited by sysctls: +kernel.pty.max = 4096 - global limit +kernel.pty.reserve = 1024 - reserve for initial instance +kernel.pty.nr - current count of ptys + +Per-instance limit could be set by adding mount option "max=<count>". +This feature was added in kernel 3.4 together with sysctl kernel.pty.reserve. +In kernels older than 3.4 sysctl kernel.pty.max works as per-instance limit. + User-space changes ------------------ diff --git a/Documentation/filesystems/nfs/fault_injection.txt b/Documentation/filesystems/nfs/fault_injection.txt index 426d166089a3..f3a5b0a8ac05 100644 --- a/Documentation/filesystems/nfs/fault_injection.txt +++ b/Documentation/filesystems/nfs/fault_injection.txt @@ -49,13 +49,13 @@ forget_locks: forget_delegations: A delegation is used to assure the client that a file, or part of a file, has not changed since the delegation was awarded. Clearing this list will - force the client to reaquire its delegation before accessing the file + force the client to reacquire its delegation before accessing the file again. recall_delegations: Delegations can be recalled by the server when another client attempts to access a file. This test will notify the client that its delegation has - been revoked, forcing the client to reaquire the delegation before using + been revoked, forcing the client to reacquire the delegation before using the file again. diff --git a/Documentation/filesystems/nfs/nfs-rdma.txt b/Documentation/filesystems/nfs/nfs-rdma.txt index 906b6c233f62..1e6564545edf 100644 --- a/Documentation/filesystems/nfs/nfs-rdma.txt +++ b/Documentation/filesystems/nfs/nfs-rdma.txt @@ -218,7 +218,7 @@ NFS/RDMA Setup /vol0 192.168.0.0/255.255.255.0(fsid=0,rw,async,insecure,no_root_squash) The IP address(es) is(are) the client's IPoIB address for an InfiniBand - HCA or the cleint's iWARP address(es) for an RNIC. + HCA or the client's iWARP address(es) for an RNIC. NOTE: The "insecure" option must be used because the NFS/RDMA client does not use a reserved port. diff --git a/Documentation/filesystems/nfs/nfsroot.txt b/Documentation/filesystems/nfs/nfsroot.txt index bb5ab6de5924..0b2883b17d4c 100644 --- a/Documentation/filesystems/nfs/nfsroot.txt +++ b/Documentation/filesystems/nfs/nfsroot.txt @@ -166,7 +166,7 @@ ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>: Value gets exported by /proc/net/pnp which is often linked on embedded systems by /etc/resolv.conf. - <dns1-ip> IP address of secound nameserver. + <dns1-ip> IP address of second nameserver. Same as above. diff --git a/Documentation/filesystems/nfs/pnfs.txt b/Documentation/filesystems/nfs/pnfs.txt index 44a9f2493a88..8de578a98222 100644 --- a/Documentation/filesystems/nfs/pnfs.txt +++ b/Documentation/filesystems/nfs/pnfs.txt @@ -64,8 +64,8 @@ table which are called by the nfs-client pnfs-core to implement the different layout types. Files-layout-driver code is in: fs/nfs/filelayout/.. directory -Objects-layout-deriver code is in: fs/nfs/objlayout/.. directory -Blocks-layout-deriver code is in: fs/nfs/blocklayout/.. directory +Objects-layout-driver code is in: fs/nfs/objlayout/.. directory +Blocks-layout-driver code is in: fs/nfs/blocklayout/.. directory Flexfiles-layout-driver code is in: fs/nfs/flexfilelayout/.. directory objects-layout setup @@ -91,7 +91,7 @@ The API to the login script is as follows: Usage: $0 -u <URI> -o <OSDNAME> -s <SYSTEMID> Options: -u target uri e.g. iscsi://<ip>:<port> - (allways exists) + (always exists) (More protocols can be defined in the future. The client does not interpret this string it is passed unchanged as received from the Server) diff --git a/Documentation/filesystems/nfs/rpc-server-gss.txt b/Documentation/filesystems/nfs/rpc-server-gss.txt index 716f4be8e8b3..310bbbaf9080 100644 --- a/Documentation/filesystems/nfs/rpc-server-gss.txt +++ b/Documentation/filesystems/nfs/rpc-server-gss.txt @@ -57,7 +57,7 @@ the Kerberos tickets, that needs to be sent through the GSS layer in order to perform context establishment. B) It does not properly handle creds where the user is member of more -than a few housand groups (the current hard limit in the kernel is 65K +than a few thousand groups (the current hard limit in the kernel is 65K groups) due to limitation on the size of the buffer that can be send back to the kernel (4KiB). diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 843b045b4069..7f5607a089b4 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -43,6 +43,7 @@ Table of Contents 3.7 /proc/<pid>/task/<tid>/children - Information about task children 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file 3.9 /proc/<pid>/map_files - Information about memory mapped files + 3.10 /proc/<pid>/timerslack_ns - Task timerslack value 4 Configuring procfs 4.1 Mount options @@ -1862,6 +1863,23 @@ time one can open(2) mappings from the listings of two processes and comparing their inode numbers to figure out which anonymous memory areas are actually shared. +3.10 /proc/<pid>/timerslack_ns - Task timerslack value +--------------------------------------------------------- +This file provides the value of the task's timerslack value in nanoseconds. +This value specifies a amount of time that normal timers may be deferred +in order to coalesce timers and avoid unnecessary wakeups. + +This allows a task's interactivity vs power consumption trade off to be +adjusted. + +Writing 0 to the file will set the tasks timerslack to the default value. + +Valid values are from 0 - ULLONG_MAX + +An application setting the value must have PTRACE_MODE_ATTACH_FSCREDS level +permissions on the task specified to change its timerslack_ns value. + + ------------------------------------------------------------------------------ Configuring procfs ------------------------------------------------------------------------------ diff --git a/Documentation/filesystems/sharedsubtree.txt b/Documentation/filesystems/sharedsubtree.txt index e3f4c778eb98..8ccfbd55244b 100644 --- a/Documentation/filesystems/sharedsubtree.txt +++ b/Documentation/filesystems/sharedsubtree.txt @@ -123,7 +123,7 @@ replicas continue to be exactly same. 2d) A unbindable mount is a unbindable private mount - let's say we have a mount at /mnt and we make is unbindable + let's say we have a mount at /mnt and we make it unbindable # mount --make-unbindable /mnt @@ -197,13 +197,13 @@ replicas continue to be exactly same. namespaces are made first class objects with user API to associate/disassociate a namespace with userid, then each user could have his/her own namespace and tailor it to his/her - requirements. Offcourse its needs support from PAM. + requirements. This needs to be supported in PAM. D) Versioned files If the entire mount tree is visible at multiple locations, then - a underlying versioning file system can return different - version of the file depending on the path used to access that + an underlying versioning file system can return different + versions of the file depending on the path used to access that file. An example is: |
