diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/Locking | 11 | ||||
| -rw-r--r-- | Documentation/filesystems/autofs4.txt | 520 | ||||
| -rw-r--r-- | Documentation/filesystems/ntfs.txt | 268 | ||||
| -rw-r--r-- | Documentation/filesystems/vfs.txt | 9 |
4 files changed, 531 insertions, 277 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index f1997e9da61..94d93b1f8b5 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -464,15 +464,12 @@ prototypes: size_t, unsigned int); ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int); - int (*setlease)(struct file *, long, struct file_lock **); + int (*setlease)(struct file *, long, struct file_lock **, void **); long (*fallocate)(struct file *, int, loff_t, loff_t); }; locking rules: - All may block except for ->setlease. - No VFS locks held on entry except for ->setlease. - -->setlease has the file_list_lock held and must not sleep. + All may block. ->llseek() locking has moved from llseek to the individual llseek implementations. If your fs is not using generic_file_llseek, you @@ -496,6 +493,10 @@ components. And there are other reasons why the current interface is a mess... ->read on directories probably must go away - we should just enforce -EISDIR in sys_read() and friends. +->setlease operations should call generic_setlease() before or after setting +the lease within the individual filesystem to record the result of the +operation + --------------------------- dquot_operations ------------------------------- prototypes: int (*write_dquot) (struct dquot *); diff --git a/Documentation/filesystems/autofs4.txt b/Documentation/filesystems/autofs4.txt new file mode 100644 index 00000000000..39d02e19fb6 --- /dev/null +++ b/Documentation/filesystems/autofs4.txt @@ -0,0 +1,520 @@ +<head> +<style> p { max-width:50em} ol, ul {max-width: 40em}</style> +</head> + +autofs - how it works +===================== + +Purpose +------- + +The goal of autofs is to provide on-demand mounting and race free +automatic unmounting of various other filesystems. This provides two +key advantages: + +1. There is no need to delay boot until all filesystems that + might be needed are mounted. Processes that try to access those + slow filesystems might be delayed but other processes can + continue freely. This is particularly important for + network filesystems (e.g. NFS) or filesystems stored on + media with a media-changing robot. + +2. The names and locations of filesystems can be stored in + a remote database and can change at any time. The content + in that data base at the time of access will be used to provide + a target for the access. The interpretation of names in the + filesystem can even be programmatic rather than database-backed, + allowing wildcards for example, and can vary based on the user who + first accessed a name. + +Context +------- + +The "autofs4" filesystem module is only one part of an autofs system. +There also needs to be a user-space program which looks up names +and mounts filesystems. This will often be the "automount" program, +though other tools including "systemd" can make use of "autofs4". +This document describes only the kernel module and the interactions +required with any user-space program. Subsequent text refers to this +as the "automount daemon" or simply "the daemon". + +"autofs4" is a Linux kernel module with provides the "autofs" +filesystem type. Several "autofs" filesystems can be mounted and they +can each be managed separately, or all managed by the same daemon. + +Content +------- + +An autofs filesystem can contain 3 sorts of objects: directories, +symbolic links and mount traps. Mount traps are directories with +extra properties as described in the next section. + +Objects can only be created by the automount daemon: symlinks are +created with a regular `symlink` system call, while directories and +mount traps are created with `mkdir`. The determination of whether a +directory should be a mount trap or not is quite _ad hoc_, largely for +historical reasons, and is determined in part by the +*direct*/*indirect*/*offset* mount options, and the *maxproto* mount option. + +If neither the *direct* or *offset* mount options are given (so the +mount is considered to be *indirect*), then the root directory is +always a regular directory, otherwise it is a mount trap when it is +empty and a regular directory when not empty. Note that *direct* and +*offset* are treated identically so a concise summary is that the root +directory is a mount trap only if the filesystem is mounted *direct* +and the root is empty. + +Directories created in the root directory are mount traps only if the +filesystem is mounted *indirect* and they are empty. + +Directories further down the tree depend on the *maxproto* mount +option and particularly whether it is less than five or not. +When *maxproto* is five, no directories further down the +tree are ever mount traps, they are always regular directories. When +the *maxproto* is four (or three), these directories are mount traps +precisely when they are empty. + +So: non-empty (i.e. non-leaf) directories are never mount traps. Empty +directories are sometimes mount traps, and sometimes not depending on +where in the tree they are (root, top level, or lower), the *maxproto*, +and whether the mount was *indirect* or not. + +Mount Traps +--------------- + +A core element of the implementation of autofs is the Mount Traps +which are provided by the Linux VFS. Any directory provided by a +filesystem can be designated as a trap. This involves two separate +features that work together to allow autofs to do its job. + +**DCACHE_NEED_AUTOMOUNT** + +If a dentry has the DCACHE_NEED_AUTOMOUNT flag set (which gets set if +the inode has S_AUTOMOUNT set, or can be set directly) then it is +(potentially) a mount trap. Any access to this directory beyond a +"`stat`" will (normally) cause the `d_op->d_automount()` dentry operation +to be called. The task of this method is to find the filesystem that +should be mounted on the directory and to return it. The VFS is +responsible for actually mounting the root of this filesystem on the +directory. + +autofs doesn't find the filesystem itself but sends a message to the +automount daemon asking it to find and mount the filesystem. The +autofs `d_automount` method then waits for the daemon to report that +everything is ready. It will then return "`NULL`" indicating that the +mount has already happened. The VFS doesn't try to mount anything but +follows down the mount that is already there. + +This functionality is sufficient for some users of mount traps such +as NFS which creates traps so that mountpoints on the server can be +reflected on the client. However it is not sufficient for autofs. As +mounting onto a directory is considered to be "beyond a `stat`", the +automount daemon would not be able to mount a filesystem on the 'trap' +directory without some way to avoid getting caught in the trap. For +that purpose there is another flag. + +**DCACHE_MANAGE_TRANSIT** + +If a dentry has DCACHE_MANAGE_TRANSIT set then two very different but +related behaviors are invoked, both using the `d_op->d_manage()` +dentry operation. + +Firstly, before checking to see if any filesystem is mounted on the +directory, d_manage() will be called with the `rcu_walk` parameter set +to `false`. It may return one of three things: + +- A return value of zero indicates that there is nothing special + about this dentry and normal checks for mounts and automounts + should proceed. + + autofs normally returns zero, but first waits for any + expiry (automatic unmounting of the mounted filesystem) to + complete. This avoids races. + +- A return value of `-EISDIR` tells the VFS to ignore any mounts + on the directory and to not consider calling `->d_automount()`. + This effectively disables the **DCACHE_NEED_AUTOMOUNT** flag + causing the directory not be a mount trap after all. + + autofs returns this if it detects that the process performing the + lookup is the automount daemon and that the mount has been + requested but has not yet completed. How it determines this is + discussed later. This allows the automount daemon not to get + caught in the mount trap. + + There is a subtlety here. It is possible that a second autofs + filesystem can be mounted below the first and for both of them to + be managed by the same daemon. For the daemon to be able to mount + something on the second it must be able to "walk" down past the + first. This means that d_manage cannot *always* return -EISDIR for + the automount daemon. It must only return it when a mount has + been requested, but has not yet completed. + + `d_manage` also returns `-EISDIR` if the dentry shouldn't be a + mount trap, either because it is a symbolic link or because it is + not empty. + +- Any other negative value is treated as an error and returned + to the caller. + + autofs can return + + - -ENOENT if the automount daemon failed to mount anything, + - -ENOMEM if it ran out of memory, + - -EINTR if a signal arrived while waiting for expiry to + complete + - or any other error sent down by the automount daemon. + + +The second use case only occurs during an "RCU-walk" and so `rcu_walk` +will be set. + +An RCU-walk is a fast and lightweight process for walking down a +filename path (i.e. it is like running on tip-toes). RCU-walk cannot +cope with all situations so when it finds a difficulty it falls back +to "REF-walk", which is slower but more robust. + +RCU-walk will never call `->d_automount`; the filesystems must already +be mounted or RCU-walk cannot handle the path. +To determine if a mount-trap is safe for RCU-walk mode it calls +`->d_manage()` with `rcu_walk` set to `true`. + +In this case `d_manage()` must avoid blocking and should avoid taking +spinlocks if at all possible. Its sole purpose is to determine if it +would be safe to follow down into any mounted directory and the only +reason that it might not be is if an expiry of the mount is +underway. + +In the `rcu_walk` case, `d_manage()` cannot return -EISDIR to tell the +VFS that this is a directory that doesn't require d_automount. If +`rcu_walk` sees a dentry with DCACHE_NEED_AUTOMOUNT set but nothing +mounted, it *will* fall back to REF-walk. `d_manage()` cannot make the +VFS remain in RCU-walk mode, but can only tell it to get out of +RCU-walk mode by returning `-ECHILD`. + +So `d_manage()`, when called with `rcu_walk` set, should either return +-ECHILD if there is any reason to believe it is unsafe to end the +mounted filesystem, and otherwise should return 0. + +autofs will return `-ECHILD` if an expiry of the filesystem has been +initiated or is being considered, otherwise it returns 0. + + +Mountpoint expiry +----------------- + +The VFS has a mechansim for automatically expiring unused mounts, +much as it can expire any unused dentry information from the dcache. +This is guided by the MNT_SHRINKABLE flag. This only applies to +mounts that were created by `d_automount()` returning a filesystem to be +mounted. As autofs doesn't return such a filesystem but leaves the +mounting to the automount daemon, it must involve the automount daemon +in unmounting as well. This also means that autofs has more control +of expiry. + +The VFS also supports "expiry" of mounts using the MNT_EXPIRE flag to +the `umount` system call. Unmounting with MNT_EXPIRE will fail unless +a previous attempt had been made, and the filesystem has been inactive +and untouched since that previous attempt. autofs4 does not depend on +this but has its own internal tracking of whether filesystems were +recently used. This allows individual names in the autofs directory +to expire separately. + +With version 4 of the protocol, the automount daemon can try to +unmount any filesystems mounted on the autofs filesystem or remove any +symbolic links or empty directories any time it likes. If the unmount +or removal is successful the filesystem will be returned to the state +it was before the mount or creation, so that any access of the name +will trigger normal auto-mount processing. In particlar, `rmdir` and +`unlink` do not leave negative entries in the dcache as a normal +filesystem would, so an attempt to access a recently-removed object is +passed to autofs for handling. + +With version 5, this is not safe except for unmounting from top-level +directories. As lower-level directories are never mount traps, other +processes will see an empty directory as soon as the filesystem is +unmounted. So it is generally safest to use the autofs expiry +protocol described below. + +Normally the daemon only wants to remove entries which haven't been +used for a while. For this purpose autofs maintains a "`last_used`" +time stamp on each directory or symlink. For symlinks it genuinely +does record the last time the symlink was "used" or followed to find +out where it points to. For directories the field is a slight +misnomer. It actually records the last time that autofs checked if +the directory or one of its descendents was busy and found that it +was. This is just as useful and doesn't require updating the field so +often. + +The daemon is able to ask autofs if anything is due to be expired, +using an `ioctl` as discussed later. For a *direct* mount, autofs +considers if the entire mount-tree can be unmounted or not. For an +*indirect* mount, autofs considers each of the names in the top level +directory to determine if any of those can be unmounted and cleaned +up. + +There is an option with indirect mounts to consider each of the leaves +that has been mounted on instead of considering the top-level names. +This is intended for compatability with version 4 of autofs and should +be considered as deprecated. + +When autofs considers a directory it checks the `last_used` time and +compares it with the "timeout" value set when the filesystem was +mounted, though this check is ignored in some cases. It also checks if +the directory or anything below it is in use. For symbolic links, +only the `last_used` time is ever considered. + +If both appear to support expiring the directory or symlink, an action +is taken. + +There are two ways to ask autofs to consider expiry. The first is to +use the **AUTOFS_IOC_EXPIRE** ioctl. This only works for indirect +mounts. If it finds something in the root directory to expire it will +return the name of that thing. Once a name has been returned the +automount daemon needs to unmount any filesystems mounted below the +name normally. As described above, this is unsafe for non-toplevel +mounts in a version-5 autofs. For this reason the current `automountd` +does not use this ioctl. + +The second mechanism uses either the **AUTOFS_DEV_IOCTL_EXPIRE_CMD** or +the **AUTOFS_IOC_EXPIRE_MULTI** ioctl. This will work for both direct and +indirect mounts. If it selects an object to expire, it will notify +the daemon using the notification mechanism described below. This +will block until the daemon acknowledges the expiry notification. +This implies that the "`EXPIRE`" ioctl must be sent from a different +thread than the one which handles notification. + +While the ioctl is blocking, the entry is marked as "expiring" and +`d_manage` will block until the daemon affirms that the unmount has +completed (together with removing any directories that might have been +necessary), or has been aborted. + +Communicating with autofs: detecting the daemon +----------------------------------------------- + +There are several forms of communication between the automount daemon +and the filesystem. As we have already seen, the daemon can create and +remove directories and symlinks using normal filesystem operations. +autofs knows whether a process requesting some operation is the daemon +or not based on its process-group id number (see getpgid(1)). + +When an autofs filesystem it mounted the pgid of the mounting +processes is recorded unless the "pgrp=" option is given, in which +case that number is recorded instead. Any request arriving from a +process in that process group is considered to come from the daemon. +If the daemon ever has to be stopped and restarted a new pgid can be +provided through an ioctl as will be described below. + +Communicating with autofs: the event pipe +----------------------------------------- + +When an autofs filesystem is mounted, the 'write' end of a pipe must +be passed using the 'fd=' mount option. autofs will write +notification messages to this pipe for the daemon to respond to. +For version 5, the format of the message is: + + struct autofs_v5_packet { + int proto_version; /* Protocol version */ + int type; /* Type of packet */ + autofs_wqt_t wait_queue_token; + __u32 dev; + __u64 ino; + __u32 uid; + __u32 gid; + __u32 pid; + __u32 tgid; + __u32 len; + char name[NAME_MAX+1]; + }; + +where the type is one of + + autofs_ptype_missing_indirect + autofs_ptype_expire_indirect + autofs_ptype_missing_direct + autofs_ptype_expire_direct + +so messages can indicate that a name is missing (something tried to +access it but it isn't there) or that it has been selected for expiry. + +The pipe will be set to "packet mode" (equivalent to passing +`O_DIRECT`) to _pipe2(2)_ so that a read from the pipe will return at +most one packet, and any unread portion of a packet will be discarded. + +The `wait_queue_token` is a unique number which can identify a +particular request to be acknowledged. When a message is sent over +the pipe the affected dentry is marked as either "active" or +"expiring" and other accesses to it block until the message is +acknowledged using one of the ioctls below and the relevant +`wait_queue_token`. + +Communicating with autofs: root directory ioctls +------------------------------------------------ + +The root directory of an autofs filesystem will respond to a number of +ioctls. The process issuing the ioctl must have the CAP_SYS_ADMIN +capability, or must be the automount daemon. + +The available ioctl commands are: + +- **AUTOFS_IOC_READY**: a notification has been handled. The argument + to the ioctl command is the "wait_queue_token" number + corresponding to the notification being acknowledged. +- **AUTOFS_IOC_FAIL**: similar to above, but indicates failure with + the error code `ENOENT`. +- **AUTOFS_IOC_CATATONIC**: Causes the autofs to enter "catatonic" + mode meaning that it stops sending notifications to the daemon. + This mode is also entered if a write to the pipe fails. +- **AUTOFS_IOC_PROTOVER**: This returns the protocol version in use. +- **AUTOFS_IOC_PROTOSUBVER**: Returns the protocol sub-version which + is really a version number for the implementation. It is + currently 2. +- **AUTOFS_IOC_SETTIMEOUT**: This passes a pointer to an unsigned + long. The value is used to set the timeout for expiry, and + the current timeout value is stored back through the pointer. +- **AUTOFS_IOC_ASKUMOUNT**: Returns, in the pointed-to `int`, 1 if + the filesystem could be unmounted. This is only a hint as + the situation could change at any instant. This call can be + use to avoid a more expensive full unmount attempt. +- **AUTOFS_IOC_EXPIRE**: as described above, this asks if there is + anything suitable to expire. A pointer to a packet: + + struct autofs_packet_expire_multi { + int proto_version; /* Protocol version */ + int type; /* Type of packet */ + autofs_wqt_t wait_queue_token; + int len; + char name[NAME_MAX+1]; + }; + + is required. This is filled in with the name of something + that can be unmounted or removed. If nothing can be expired, + `errno` is set to `EAGAIN`. Even though a `wait_queue_token` + is present in the structure, no "wait queue" is established + and no acknowledgment is needed. +- **AUTOFS_IOC_EXPIRE_MULTI**: This is similar to + **AUTOFS_IOC_EXPIRE** except that it causes notification to be + sent to the daemon, and it blocks until the daemon acknowledges. + The argument is an integer which can contain two different flags. + + **AUTOFS_EXP_IMMEDIATE** causes `last_used` time to be ignored + and objects are expired if the are not in use. + + **AUTOFS_EXP_LEAVES** will select a leaf rather than a top-level + name to expire. This is only safe when *maxproto* is 4. + +Communicating with autofs: char-device ioctls +--------------------------------------------- + +It is not always possible to open the root of an autofs filesystem, +particularly a *direct* mounted filesystem. If the automount daemon +is restarted there is no way for it to regain control of existing +mounts using any of the above communication channels. To address this +need there is a "miscellaneous" character device (major 10, minor 235) +which can be used to communicate directly with the autofs filesystem. +It requires CAP_SYS_ADMIN for access. + +The `ioctl`s that can be used on this device are described in a separate +document `autofs4-mount-control.txt`, and are summarized briefly here. +Each ioctl is passed a pointer to an `autofs_dev_ioctl` structure: + + struct autofs_dev_ioctl { + __u32 ver_major; + __u32 ver_minor; + __u32 size; /* total size of data passed in + * including this struct */ + __s32 ioctlfd; /* automount command fd */ + + __u32 arg1; /* Command parameters */ + __u32 arg2; + + char path[0]; + }; + +For the **OPEN_MOUNT** and **IS_MOUNTPOINT** commands, the target +filesystem is identified by the `path`. All other commands identify +the filesystem by the `ioctlfd` which is a file descriptor open on the +root, and which can be returned by **OPEN_MOUNT**. + +The `ver_major` and `ver_minor` are in/out parameters which check that +the requested version is supported, and report the maximum version +that the kernel module can support. + +Commands are: + +- **AUTOFS_DEV_IOCTL_VERSION_CMD**: does nothing, except validate and + set version numbers. +- **AUTOFS_DEV_IOCTL_OPENMOUNT_CMD**: return an open file descriptor + on the root of an autofs filesystem. The filesystem is identified + by name and device number, which is stored in `arg1`. Device + numbers for existing filesystems can be found in + `/proc/self/mountinfo`. +- **AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD**: same as `close(ioctlfd)`. +- **AUTOFS_DEV_IOCTL_SETPIPEFD_CMD**: if the filesystem is in + catatonic mode, this can provide the write end of a new pipe + in `arg1` to re-establish communication with a daemon. The + process group of the calling process is used to identify the + daemon. +- **AUTOFS_DEV_IOCTL_REQUESTER_CMD**: `path` should be a + name within the filesystem that has been auto-mounted on. + arg1 is the dev number of the underlying autofs. On successful + return, `arg1` and `arg2` will be the UID and GID of the process + which triggered that mount. + +- **AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD**: Check if path is a + mountpoint of a particular type - see separate documentation for + details. + +- **AUTOFS_DEV_IOCTL_PROTOVER_CMD**: +- **AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD**: +- **AUTOFS_DEV_IOCTL_READY_CMD**: +- **AUTOFS_DEV_IOCTL_FAIL_CMD**: +- **AUTOFS_DEV_IOCTL_CATATONIC_CMD**: +- **AUTOFS_DEV_IOCTL_TIMEOUT_CMD**: +- **AUTOFS_DEV_IOCTL_EXPIRE_CMD**: +- **AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD**: These all have the same + function as the similarly named **AUTOFS_IOC** ioctls, except + that **FAIL** can be given an explicit error number in `arg1` + instead of assuming `ENOENT`, and this **EXPIRE** command + corresponds to **AUTOFS_IOC_EXPIRE_MULTI**. + +Catatonic mode +-------------- + +As mentioned, an autofs mount can enter "catatonic" mode. This +happens if a write to the notification pipe fails, or if it is +explicitly requested by an `ioctl`. + +When entering catatonic mode, the pipe is closed and any pending +notifications are acknowledged with the error `ENOENT`. + +Once in catatonic mode attempts to access non-existing names will +result in `ENOENT` while attempts to access existing directories will +be treated in the same way as if they came from the daemon, so mount +traps will not fire. + +When the filesystem is mounted a _uid_ and _gid_ can be given which +set the ownership of directories and symbolic links. When the +filesystem is in catatonic mode, any process with a matching UID can +create directories or symlinks in the root directory, but not in other +directories. + +Catatonic mode can only be left via the +**AUTOFS_DEV_IOCTL_OPENMOUNT_CMD** ioctl on the `/dev/autofs`. + +autofs, name spaces, and shared mounts +-------------------------------------- + +With bind mounts and name spaces it is possible for an autofs +filesystem to appear at multiple places in one or more filesystem +name spaces. For this to work sensibly, the autofs filesystem should +always be mounted "shared". e.g. + +> `mount --make-shared /autofs/mount/point` + +The automount daemon is only able to mange a single mount location for +an autofs filesystem and if mounts on that are not 'shared', other +locations will not behave as expected. In particular access to those +other locations will likely result in the `ELOOP` error + +> Too many levels of symbolic links diff --git a/Documentation/filesystems/ntfs.txt b/Documentation/filesystems/ntfs.txt index 61947facfc0..553f10d0307 100644 --- a/Documentation/filesystems/ntfs.txt +++ b/Documentation/filesystems/ntfs.txt @@ -14,7 +14,6 @@ Table of contents - The Device-Mapper driver - The Software RAID / MD driver - Limitations when using the MD driver -- ChangeLog Overview @@ -450,270 +449,3 @@ number of sectors BEFORE attempting to use it. You have been warned! Even better is to simply use the Device-Mapper for linear raid and then you do not have this problem with odd numbers of sectors. - - -ChangeLog -========= - -2.1.30: - - Fix writev() (it kept writing the first segment over and over again - instead of moving onto subsequent segments). - - Fix crash in ntfs_mft_record_alloc() when mapping the new extent mft - record failed. -2.1.29: - - Fix a deadlock when mounting read-write. -2.1.28: - - Fix a deadlock. -2.1.27: - - Implement page migration support so the kernel can move memory used - by NTFS files and directories around for management purposes. - - Add support for writing to sparse files created with Windows XP SP2. - - Many minor improvements and bug fixes. -2.1.26: - - Implement support for sector sizes above 512 bytes (up to the maximum - supported by NTFS which is 4096 bytes). - - Enhance support for NTFS volumes which were supported by Windows but - not by Linux due to invalid attribute list attribute flags. - - A few minor updates and bug fixes. -2.1.25: - - Write support is now extended with write(2) being able to both - overwrite existing file data and to extend files. Also, if a write - to a sparse region occurs, write(2) will fill in the hole. Note, - mmap(2) based writes still do not support writing into holes or - writing beyond the initialized size. - - Write support has a new feature and that is that truncate(2) and - open(2) with O_TRUNC are now implemented thus files can be both made - smaller and larger. - - Note: Both write(2) and truncate(2)/open(2) with O_TRUNC still have - limitations in that they - - only provide limited support for highly fragmented files. - - only work on regular, i.e. uncompressed and unencrypted files. - - never create sparse files although this will change once directory - operations are implemented. - - Lots of bug fixes and enhancements across the board. -2.1.24: - - Support journals ($LogFile) which have been modified by chkdsk. This - means users can boot into Windows after we marked the volume dirty. - The Windows boot will run chkdsk and then reboot. The user can then - immediately boot into Linux rather than having to do a full Windows - boot first before rebooting into Linux and we will recognize such a - journal and empty it as it is clean by definition. - - Support journals ($LogFile) with only one restart page as well as - journals with two different restart pages. We sanity check both and - either use the only sane one or the more recent one of the two in the - case that both are valid. - - Lots of bug fixes and enhancements across the board. -2.1.23: - - Stamp the user space journal, aka transaction log, aka $UsnJrnl, if - it is present and active thus telling Windows and applications using - the transaction log that changes can have happened on the volume - which are not recorded in $UsnJrnl. - - Detect the case when Windows has been hibernated (suspended to disk) - and if this is the case do not allow (re)mounting read-write to - prevent data corruption when you boot back into the suspended - Windows session. - - Implement extension of resident files using the normal file write - code paths, i.e. most very small files can be extended to be a little - bit bigger but not by much. - - Add new mount option "disable_sparse". (See list of mount options - above for details.) - - Improve handling of ntfs volumes with errors and strange boot sectors - in particular. - - Fix various bugs including a nasty deadlock that appeared in recent - kernels (around 2.6.11-2.6.12 timeframe). -2.1.22: - - Improve handling of ntfs volumes with errors. - - Fix various bugs and race conditions. -2.1.21: - - Fix several race conditions and various other bugs. - - Many internal cleanups, code reorganization, optimizations, and mft - and index record writing code rewritten to fit in with the changes. - - Update Documentation/filesystems/ntfs.txt with instructions on how to - use the Device-Mapper driver with NTFS ftdisk/LDM raid. -2.1.20: - - Fix two stupid bugs introduced in 2.1.18 release. -2.1.19: - - Minor bugfix in handling of the default upcase table. - - Many internal cleanups and improvements. Many thanks to Linus - Torvalds and Al Viro for the help and advice with the sparse - annotations and cleanups. -2.1.18: - - Fix scheduling latencies at mount time. (Ingo Molnar) - - Fix endianness bug in a little traversed portion of the attribute - lookup code. -2.1.17: - - Fix bugs in mount time error code paths. -2.1.16: - - Implement access time updates (including mtime and ctime). - - Implement fsync(2), fdatasync(2), and msync(2) system calls. - - Enable the readv(2) and writev(2) system calls. - - Enable access via the asynchronous io (aio) API by adding support for - the aio_read(3) and aio_write(3) functions. -2.1.15: - - Invalidate quotas when (re)mounting read-write. - NOTE: This now only leave user space journalling on the side. (See - note for version 2.1.13, below.) -2.1.14: - - Fix an NFSd caused deadlock reported by several users. -2.1.13: - - Implement writing of inodes (access time updates are not implemented - yet so mounting with -o noatime,nodiratime is enforced). - - Enable writing out of resident files so you can now overwrite any - uncompressed, unencrypted, nonsparse file as long as you do not - change the file size. - - Add housekeeping of ntfs system files so that ntfsfix no longer needs - to be run after writing to an NTFS volume. - NOTE: This still leaves quota tracking and user space journalling on - the side but they should not cause data corruption. In the worst - case the charged quotas will be out of date ($Quota) and some - userspace applications might get confused due to the out of date - userspace journal ($UsnJrnl). -2.1.12: - - Fix the second fix to the decompression engine from the 2.1.9 release - and some further internals cleanups. -2.1.11: - - Driver internal cleanups. -2.1.10: - - Force read-only (re)mounting of volumes with unsupported volume - flags and various cleanups. -2.1.9: - - Fix two bugs in handling of corner cases in the decompression engine. -2.1.8: - - Read the $MFT mirror and compare it to the $MFT and if the two do not - match, force a read-only mount and do not allow read-write remounts. - - Read and parse the $LogFile journal and if it indicates that the - volume was not shutdown cleanly, force a read-only mount and do not - allow read-write remounts. If the $LogFile indicates a clean - shutdown and a read-write (re)mount is requested, empty $LogFile to - ensure that Windows cannot cause data corruption by replaying a stale - journal after Linux has written to the volume. - - Improve time handling so that the NTFS time is fully preserved when - converted to kernel time and only up to 99 nano-seconds are lost when - kernel time is converted to NTFS time. -2.1.7: - - Enable NFS exporting of mounted NTFS volumes. -2.1.6: - - Fix minor bug in handling of compressed directories that fixes the - erroneous "du" and "stat" output people reported. -2.1.5: - - Minor bug fix in attribute list attribute handling that fixes the - I/O errors on "ls" of certain fragmented files found by at least two - people running Windows XP. -2.1.4: - - Minor update allowing compilation with all gcc versions (well, the - ones the kernel can be compiled with anyway). -2.1.3: - - Major bug fixes for reading files and volumes in corner cases which - were being hit by Windows 2k/XP users. -2.1.2: - - Major bug fixes alleviating the hangs in statfs experienced by some - users. -2.1.1: - - Update handling of compressed files so people no longer get the - frequently reported warning messages about initialized_size != - data_size. -2.1.0: - - Add configuration option for developmental write support. - - Initial implementation of file overwriting. (Writes to resident files - are not written out to disk yet, so avoid writing to files smaller - than about 1kiB.) - - Intercept/abort changes in file size as they are not implemented yet. -2.0.25: - - Minor bugfixes in error code paths and small cleanups. -2.0.24: - - Small internal cleanups. - - Support for sendfile system call. (Christoph Hellwig) -2.0.23: - - Massive internal locking changes to mft record locking. Fixes - various race conditions and deadlocks. - - Fix ntfs over loopback for compressed files by adding an - optimization barrier. (gcc was screwing up otherwise ?) - Thanks go to Christoph Hellwig for pointing these two out: - - Remove now unused function fs/ntfs/malloc.h::vmalloc_nofs(). - - Fix ntfs_free() for ia64 and parisc. -2.0.22: - - Small internal cleanups. -2.0.21: - These only affect 32-bit architectures: - - Check for, and refuse to mount too large volumes (maximum is 2TiB). - - Check for, and refuse to open too large files and directories - (maximum is 16TiB). -2.0.20: - - Support non-resident directory index bitmaps. This means we now cope - with huge directories without problems. - - Fix a page leak that manifested itself in some cases when reading - directory contents. - - Internal cleanups. -2.0.19: - - Fix race condition and improvements in block i/o interface. - - Optimization when reading compressed files. -2.0.18: - - Fix race condition in reading of compressed files. -2.0.17: - - Cleanups and optimizations. -2.0.16: - - Fix stupid bug introduced in 2.0.15 in new attribute inode API. - - Big internal cleanup replacing the mftbmp access hacks by using the - new attribute inode API instead. -2.0.15: - - Bug fix in parsing of remount options. - - Internal changes implementing attribute (fake) inodes allowing all - attribute i/o to go via the page cache and to use all the normal - vfs/mm functionality. -2.0.14: - - Internal changes improving run list merging code and minor locking - change to not rely on BKL in ntfs_statfs(). -2.0.13: - - Internal changes towards using iget5_locked() in preparation for - fake inodes and small cleanups to ntfs_volume structure. -2.0.12: - - Internal cleanups in address space operations made possible by the - changes introduced in the previous release. -2.0.11: - - Internal updates and cleanups introducing the first step towards - fake inode based attribute i/o. -2.0.10: - - Microsoft says that the maximum number of inodes is 2^32 - 1. Update - the driver accordingly to only use 32-bits to store inode numbers on - 32-bit architectures. This improves the speed of the driver a little. -2.0.9: - - Change decompression engine to use a single buffer. This should not - affect performance except perhaps on the most heavy i/o on SMP - systems when accessing multiple compressed files from multiple - devices simultaneously. - - Minor updates and cleanups. -2.0.8: - - Remove now obsolete show_inodes and posix mount option(s). - - Restore show_sys_files mount option. - - Add new mount option case_sensitive, to determine if the driver - treats file names as case sensitive or not. - - Mostly drop support for short file names (for backwards compatibility - we only support accessing files via their short file name if one - exists). - - Fix dcache aliasing issues wrt short/long file names. - - Cleanups and minor fixes. -2.0.7: - - Just cleanups. -2.0.6: - - Major bugfix to make compatible with other kernel changes. This fixes - the hangs/oopses on umount. - - Locking cleanup in directory operations (remove BKL usage). -2.0.5: - - Major buffer overflow bug fix. - - Minor cleanups and updates for kernel 2.5.12. -2.0.4: - - Cleanups and updates for kernel 2.5.11. -2.0.3: - - Small bug fixes, cleanups, and performance improvements. -2.0.2: - - Use default fmask of 0177 so that files are no executable by default. - If you want owner executable files, just use fmask=0077. - - Update for kernel 2.5.9 but preserve backwards compatibility with - kernel 2.5.7. - - Minor bug fixes, cleanups, and updates. -2.0.1: - - Minor updates, primarily set the executable bit by default on files - so they can be executed. -2.0.0: - - Started ChangeLog. - diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index 61d65cc65c5..fceff7c00a3 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -237,7 +237,7 @@ noted. This means that most methods can block safely. All methods are only called from a process context (i.e. not from an interrupt handler or bottom half). - alloc_inode: this method is called by inode_alloc() to allocate memory + alloc_inode: this method is called by alloc_inode() to allocate memory for struct inode and initialize it. If this function is not defined, a simple 'struct inode' is allocated. Normally alloc_inode will be used to allocate a larger structure which @@ -826,7 +826,7 @@ struct file_operations { int (*flock) (struct file *, int, struct file_lock *); ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, size_t, unsigned int); ssize_t (*splice_read)(struct file *, struct pipe_inode_info *, size_t, unsigned int); - int (*setlease)(struct file *, long arg, struct file_lock **); + int (*setlease)(struct file *, long arg, struct file_lock **, void **); long (*fallocate)(struct file *, int mode, loff_t offset, loff_t len); int (*show_fdinfo)(struct seq_file *m, struct file *f); }; @@ -895,8 +895,9 @@ otherwise noted. splice_read: called by the VFS to splice data from file to a pipe. This method is used by the splice(2) system call - setlease: called by the VFS to set or release a file lock lease. - setlease has the file_lock_lock held and must not sleep. + setlease: called by the VFS to set or release a file lock lease. setlease + implementations should call generic_setlease to record or remove + the lease in the inode after setting it. fallocate: called by the VFS to preallocate blocks or punch a hole. |