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authorIngo Molnar <mingo@kernel.org>2015-02-26 14:24:50 +0300
committerIngo Molnar <mingo@kernel.org>2015-02-26 14:24:50 +0300
commite9e4e44309f866b115d08ab4a54834008c50a8a4 (patch)
treeae9f91e682a4d6592ef263f30a4a0b1a862b7987 /Documentation/filesystems
parent8a26ce4e544659256349551283414df504889a59 (diff)
parentc517d838eb7d07bbe9507871fab3931deccff539 (diff)
downloadlinux-e9e4e44309f866b115d08ab4a54834008c50a8a4.tar.xz
Merge tag 'v4.0-rc1' into perf/core, to refresh the tree
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/00-INDEX5
-rw-r--r--Documentation/filesystems/Locking5
-rw-r--r--Documentation/filesystems/dax.txt94
-rw-r--r--Documentation/filesystems/ext2.txt5
-rw-r--r--Documentation/filesystems/ext4.txt4
-rw-r--r--Documentation/filesystems/f2fs.txt6
-rw-r--r--Documentation/filesystems/fiemap.txt3
-rw-r--r--Documentation/filesystems/inotify.txt197
-rw-r--r--Documentation/filesystems/nfs/nfs41-server.txt23
-rw-r--r--Documentation/filesystems/nfs/pnfs-block-server.txt37
-rw-r--r--Documentation/filesystems/nfs/pnfs.txt13
-rw-r--r--Documentation/filesystems/ocfs2.txt4
-rw-r--r--Documentation/filesystems/overlayfs.txt28
-rw-r--r--Documentation/filesystems/proc.txt62
-rw-r--r--Documentation/filesystems/seq_file.txt12
-rw-r--r--Documentation/filesystems/vfs.txt7
-rw-r--r--Documentation/filesystems/xfs.txt22
-rw-r--r--Documentation/filesystems/xip.txt68
18 files changed, 276 insertions, 319 deletions
diff --git a/Documentation/filesystems/00-INDEX b/Documentation/filesystems/00-INDEX
index ac28149aede4..9922939e7d99 100644
--- a/Documentation/filesystems/00-INDEX
+++ b/Documentation/filesystems/00-INDEX
@@ -34,6 +34,9 @@ configfs/
- directory containing configfs documentation and example code.
cramfs.txt
- info on the cram filesystem for small storage (ROMs etc).
+dax.txt
+ - info on avoiding the page cache for files stored on CPU-addressable
+ storage devices.
debugfs.txt
- info on the debugfs filesystem.
devpts.txt
@@ -154,5 +157,3 @@ xfs-self-describing-metadata.txt
- info on XFS Self Describing Metadata.
xfs.txt
- info and mount options for the XFS filesystem.
-xip.txt
- - info on execute-in-place for file mappings.
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index b30753cbf431..f91926f2f482 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -164,8 +164,6 @@ the block device inode. See there for more details.
--------------------------- file_system_type ---------------------------
prototypes:
- int (*get_sb) (struct file_system_type *, int,
- const char *, void *, struct vfsmount *);
struct dentry *(*mount) (struct file_system_type *, int,
const char *, void *);
void (*kill_sb) (struct super_block *);
@@ -199,8 +197,6 @@ prototypes:
int (*releasepage) (struct page *, int);
void (*freepage)(struct page *);
int (*direct_IO)(int, struct kiocb *, struct iov_iter *iter, loff_t offset);
- int (*get_xip_mem)(struct address_space *, pgoff_t, int, void **,
- unsigned long *);
int (*migratepage)(struct address_space *, struct page *, struct page *);
int (*launder_page)(struct page *);
int (*is_partially_uptodate)(struct page *, unsigned long, unsigned long);
@@ -225,7 +221,6 @@ invalidatepage: yes
releasepage: yes
freepage: yes
direct_IO:
-get_xip_mem: maybe
migratepage: yes (both)
launder_page: yes
is_partially_uptodate: yes
diff --git a/Documentation/filesystems/dax.txt b/Documentation/filesystems/dax.txt
new file mode 100644
index 000000000000..baf41118660d
--- /dev/null
+++ b/Documentation/filesystems/dax.txt
@@ -0,0 +1,94 @@
+Direct Access for files
+-----------------------
+
+Motivation
+----------
+
+The page cache is usually used to buffer reads and writes to files.
+It is also used to provide the pages which are mapped into userspace
+by a call to mmap.
+
+For block devices that are memory-like, the page cache pages would be
+unnecessary copies of the original storage. The DAX code removes the
+extra copy by performing reads and writes directly to the storage device.
+For file mappings, the storage device is mapped directly into userspace.
+
+
+Usage
+-----
+
+If you have a block device which supports DAX, you can make a filesystem
+on it as usual. When mounting it, use the -o dax option manually
+or add 'dax' to the options in /etc/fstab.
+
+
+Implementation Tips for Block Driver Writers
+--------------------------------------------
+
+To support DAX in your block driver, implement the 'direct_access'
+block device operation. It is used to translate the sector number
+(expressed in units of 512-byte sectors) to a page frame number (pfn)
+that identifies the physical page for the memory. It also returns a
+kernel virtual address that can be used to access the memory.
+
+The direct_access method takes a 'size' parameter that indicates the
+number of bytes being requested. The function should return the number
+of bytes that can be contiguously accessed at that offset. It may also
+return a negative errno if an error occurs.
+
+In order to support this method, the storage must be byte-accessible by
+the CPU at all times. If your device uses paging techniques to expose
+a large amount of memory through a smaller window, then you cannot
+implement direct_access. Equally, if your device can occasionally
+stall the CPU for an extended period, you should also not attempt to
+implement direct_access.
+
+These block devices may be used for inspiration:
+- axonram: Axon DDR2 device driver
+- brd: RAM backed block device driver
+- dcssblk: s390 dcss block device driver
+
+
+Implementation Tips for Filesystem Writers
+------------------------------------------
+
+Filesystem support consists of
+- adding support to mark inodes as being DAX by setting the S_DAX flag in
+ i_flags
+- implementing the direct_IO address space operation, and calling
+ dax_do_io() instead of blockdev_direct_IO() if S_DAX is set
+- implementing an mmap file operation for DAX files which sets the
+ VM_MIXEDMAP flag on the VMA, and setting the vm_ops to include handlers
+ for fault and page_mkwrite (which should probably call dax_fault() and
+ dax_mkwrite(), passing the appropriate get_block() callback)
+- calling dax_truncate_page() instead of block_truncate_page() for DAX files
+- calling dax_zero_page_range() instead of zero_user() for DAX files
+- ensuring that there is sufficient locking between reads, writes,
+ truncates and page faults
+
+The get_block() callback passed to the DAX functions may return
+uninitialised extents. If it does, it must ensure that simultaneous
+calls to get_block() (for example by a page-fault racing with a read()
+or a write()) work correctly.
+
+These filesystems may be used for inspiration:
+- ext2: the second extended filesystem, see Documentation/filesystems/ext2.txt
+- ext4: the fourth extended filesystem, see Documentation/filesystems/ext4.txt
+
+
+Shortcomings
+------------
+
+Even if the kernel or its modules are stored on a filesystem that supports
+DAX on a block device that supports DAX, they will still be copied into RAM.
+
+The DAX code does not work correctly on architectures which have virtually
+mapped caches such as ARM, MIPS and SPARC.
+
+Calling get_user_pages() on a range of user memory that has been mmaped
+from a DAX file will fail as there are no 'struct page' to describe
+those pages. This problem is being worked on. That means that O_DIRECT
+reads/writes to those memory ranges from a non-DAX file will fail (note
+that O_DIRECT reads/writes _of a DAX file_ do work, it is the memory
+that is being accessed that is key here). Other things that will not
+work include RDMA, sendfile() and splice().
diff --git a/Documentation/filesystems/ext2.txt b/Documentation/filesystems/ext2.txt
index 67639f905f10..b9714569e472 100644
--- a/Documentation/filesystems/ext2.txt
+++ b/Documentation/filesystems/ext2.txt
@@ -20,6 +20,9 @@ minixdf Makes `df' act like Minix.
check=none, nocheck (*) Don't do extra checking of bitmaps on mount
(check=normal and check=strict options removed)
+dax Use direct access (no page cache). See
+ Documentation/filesystems/dax.txt.
+
debug Extra debugging information is sent to the
kernel syslog. Useful for developers.
@@ -56,8 +59,6 @@ noacl Don't support POSIX ACLs.
nobh Do not attach buffer_heads to file pagecache.
-xip Use execute in place (no caching) if possible
-
grpquota,noquota,quota,usrquota Quota options are silently ignored by ext2.
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 919a3293aaa4..6c0108eb0137 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -386,6 +386,10 @@ max_dir_size_kb=n This limits the size of directories so that any
i_version Enable 64-bit inode version support. This option is
off by default.
+dax Use direct access (no page cache). See
+ Documentation/filesystems/dax.txt. Note that
+ this option is incompatible with data=journal.
+
Data Mode
=========
There are 3 different data modes:
diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt
index e0950c483c22..dac11d7fef27 100644
--- a/Documentation/filesystems/f2fs.txt
+++ b/Documentation/filesystems/f2fs.txt
@@ -106,6 +106,8 @@ background_gc=%s Turn on/off cleaning operations, namely garbage
Default value for this option is on. So garbage
collection is on by default.
disable_roll_forward Disable the roll-forward recovery routine
+norecovery Disable the roll-forward recovery routine, mounted read-
+ only (i.e., -o ro,disable_roll_forward)
discard Issue discard/TRIM commands when a segment is cleaned.
no_heap Disable heap-style segment allocation which finds free
segments for data from the beginning of main area, while
@@ -197,6 +199,10 @@ Files in /sys/fs/f2fs/<devname>
checkpoint is triggered, and issued during the
checkpoint. By default, it is disabled with 0.
+ trim_sections This parameter controls the number of sections
+ to be trimmed out in batch mode when FITRIM
+ conducts. 32 sections is set by default.
+
ipu_policy This parameter controls the policy of in-place
updates in f2fs. There are five policies:
0x01: F2FS_IPU_FORCE, 0x02: F2FS_IPU_SSR,
diff --git a/Documentation/filesystems/fiemap.txt b/Documentation/filesystems/fiemap.txt
index 1b805a0efbb0..f6d9c99103a4 100644
--- a/Documentation/filesystems/fiemap.txt
+++ b/Documentation/filesystems/fiemap.txt
@@ -196,7 +196,8 @@ struct fiemap_extent_info {
};
It is intended that the file system should not need to access any of this
-structure directly.
+structure directly. Filesystem handlers should be tolerant to signals and return
+EINTR once fatal signal received.
Flag checking should be done at the beginning of the ->fiemap callback via the
diff --git a/Documentation/filesystems/inotify.txt b/Documentation/filesystems/inotify.txt
index cfd02712b83e..51f61db787fb 100644
--- a/Documentation/filesystems/inotify.txt
+++ b/Documentation/filesystems/inotify.txt
@@ -4,201 +4,10 @@
Document started 15 Mar 2005 by Robert Love <rml@novell.com>
+Document updated 4 Jan 2015 by Zhang Zhen <zhenzhang.zhang@huawei.com>
+ --Deleted obsoleted interface, just refer to manpages for user interface.
-
-(i) User Interface
-
-Inotify is controlled by a set of three system calls and normal file I/O on a
-returned file descriptor.
-
-First step in using inotify is to initialise an inotify instance:
-
- int fd = inotify_init ();
-
-Each instance is associated with a unique, ordered queue.
-
-Change events are managed by "watches". A watch is an (object,mask) pair where
-the object is a file or directory and the mask is a bit mask of one or more
-inotify events that the application wishes to receive. See <linux/inotify.h>
-for valid events. A watch is referenced by a watch descriptor, or wd.
-
-Watches are added via a path to the file.
-
-Watches on a directory will return events on any files inside of the directory.
-
-Adding a watch is simple:
-
- int wd = inotify_add_watch (fd, path, mask);
-
-Where "fd" is the return value from inotify_init(), path is the path to the
-object to watch, and mask is the watch mask (see <linux/inotify.h>).
-
-You can update an existing watch in the same manner, by passing in a new mask.
-
-An existing watch is removed via
-
- int ret = inotify_rm_watch (fd, wd);
-
-Events are provided in the form of an inotify_event structure that is read(2)
-from a given inotify instance. The filename is of dynamic length and follows
-the struct. It is of size len. The filename is padded with null bytes to
-ensure proper alignment. This padding is reflected in len.
-
-You can slurp multiple events by passing a large buffer, for example
-
- size_t len = read (fd, buf, BUF_LEN);
-
-Where "buf" is a pointer to an array of "inotify_event" structures at least
-BUF_LEN bytes in size. The above example will return as many events as are
-available and fit in BUF_LEN.
-
-Each inotify instance fd is also select()- and poll()-able.
-
-You can find the size of the current event queue via the standard FIONREAD
-ioctl on the fd returned by inotify_init().
-
-All watches are destroyed and cleaned up on close.
-
-
-(ii)
-
-Prototypes:
-
- int inotify_init (void);
- int inotify_add_watch (int fd, const char *path, __u32 mask);
- int inotify_rm_watch (int fd, __u32 mask);
-
-
-(iii) Kernel Interface
-
-Inotify's kernel API consists a set of functions for managing watches and an
-event callback.
-
-To use the kernel API, you must first initialize an inotify instance with a set
-of inotify_operations. You are given an opaque inotify_handle, which you use
-for any further calls to inotify.
-
- struct inotify_handle *ih = inotify_init(my_event_handler);
-
-You must provide a function for processing events and a function for destroying
-the inotify watch.
-
- void handle_event(struct inotify_watch *watch, u32 wd, u32 mask,
- u32 cookie, const char *name, struct inode *inode)
-
- watch - the pointer to the inotify_watch that triggered this call
- wd - the watch descriptor
- mask - describes the event that occurred
- cookie - an identifier for synchronizing events
- name - the dentry name for affected files in a directory-based event
- inode - the affected inode in a directory-based event
-
- void destroy_watch(struct inotify_watch *watch)
-
-You may add watches by providing a pre-allocated and initialized inotify_watch
-structure and specifying the inode to watch along with an inotify event mask.
-You must pin the inode during the call. You will likely wish to embed the
-inotify_watch structure in a structure of your own which contains other
-information about the watch. Once you add an inotify watch, it is immediately
-subject to removal depending on filesystem events. You must grab a reference if
-you depend on the watch hanging around after the call.
-
- inotify_init_watch(&my_watch->iwatch);
- inotify_get_watch(&my_watch->iwatch); // optional
- s32 wd = inotify_add_watch(ih, &my_watch->iwatch, inode, mask);
- inotify_put_watch(&my_watch->iwatch); // optional
-
-You may use the watch descriptor (wd) or the address of the inotify_watch for
-other inotify operations. You must not directly read or manipulate data in the
-inotify_watch. Additionally, you must not call inotify_add_watch() more than
-once for a given inotify_watch structure, unless you have first called either
-inotify_rm_watch() or inotify_rm_wd().
-
-To determine if you have already registered a watch for a given inode, you may
-call inotify_find_watch(), which gives you both the wd and the watch pointer for
-the inotify_watch, or an error if the watch does not exist.
-
- wd = inotify_find_watch(ih, inode, &watchp);
-
-You may use container_of() on the watch pointer to access your own data
-associated with a given watch. When an existing watch is found,
-inotify_find_watch() bumps the refcount before releasing its locks. You must
-put that reference with:
-
- put_inotify_watch(watchp);
-
-Call inotify_find_update_watch() to update the event mask for an existing watch.
-inotify_find_update_watch() returns the wd of the updated watch, or an error if
-the watch does not exist.
-
- wd = inotify_find_update_watch(ih, inode, mask);
-
-An existing watch may be removed by calling either inotify_rm_watch() or
-inotify_rm_wd().
-
- int ret = inotify_rm_watch(ih, &my_watch->iwatch);
- int ret = inotify_rm_wd(ih, wd);
-
-A watch may be removed while executing your event handler with the following:
-
- inotify_remove_watch_locked(ih, iwatch);
-
-Call inotify_destroy() to remove all watches from your inotify instance and
-release it. If there are no outstanding references, inotify_destroy() will call
-your destroy_watch op for each watch.
-
- inotify_destroy(ih);
-
-When inotify removes a watch, it sends an IN_IGNORED event to your callback.
-You may use this event as an indication to free the watch memory. Note that
-inotify may remove a watch due to filesystem events, as well as by your request.
-If you use IN_ONESHOT, inotify will remove the watch after the first event, at
-which point you may call the final inotify_put_watch.
-
-(iv) Kernel Interface Prototypes
-
- struct inotify_handle *inotify_init(struct inotify_operations *ops);
-
- inotify_init_watch(struct inotify_watch *watch);
-
- s32 inotify_add_watch(struct inotify_handle *ih,
- struct inotify_watch *watch,
- struct inode *inode, u32 mask);
-
- s32 inotify_find_watch(struct inotify_handle *ih, struct inode *inode,
- struct inotify_watch **watchp);
-
- s32 inotify_find_update_watch(struct inotify_handle *ih,
- struct inode *inode, u32 mask);
-
- int inotify_rm_wd(struct inotify_handle *ih, u32 wd);
-
- int inotify_rm_watch(struct inotify_handle *ih,
- struct inotify_watch *watch);
-
- void inotify_remove_watch_locked(struct inotify_handle *ih,
- struct inotify_watch *watch);
-
- void inotify_destroy(struct inotify_handle *ih);
-
- void get_inotify_watch(struct inotify_watch *watch);
- void put_inotify_watch(struct inotify_watch *watch);
-
-
-(v) Internal Kernel Implementation
-
-Each inotify instance is represented by an inotify_handle structure.
-Inotify's userspace consumers also have an inotify_device which is
-associated with the inotify_handle, and on which events are queued.
-
-Each watch is associated with an inotify_watch structure. Watches are chained
-off of each associated inotify_handle and each associated inode.
-
-See fs/notify/inotify/inotify_fsnotify.c and fs/notify/inotify/inotify_user.c
-for the locking and lifetime rules.
-
-
-(vi) Rationale
+(i) Rationale
Q: What is the design decision behind not tying the watch to the open fd of
the watched object?
diff --git a/Documentation/filesystems/nfs/nfs41-server.txt b/Documentation/filesystems/nfs/nfs41-server.txt
index c49cd7e796e7..682a59fabe3f 100644
--- a/Documentation/filesystems/nfs/nfs41-server.txt
+++ b/Documentation/filesystems/nfs/nfs41-server.txt
@@ -24,11 +24,6 @@ focuses on the mandatory-to-implement NFSv4.1 Sessions, providing
"exactly once" semantics and better control and throttling of the
resources allocated for each client.
-Other NFSv4.1 features, Parallel NFS operations in particular,
-are still under development out of tree.
-See http://wiki.linux-nfs.org/wiki/index.php/PNFS_prototype_design
-for more information.
-
The table below, taken from the NFSv4.1 document, lists
the operations that are mandatory to implement (REQ), optional
(OPT), and NFSv4.0 operations that are required not to implement (MNI)
@@ -43,9 +38,7 @@ The OPTIONAL features identified and their abbreviations are as follows:
The following abbreviations indicate the linux server implementation status.
I Implemented NFSv4.1 operations.
NS Not Supported.
- NS* unimplemented optional feature.
- P pNFS features implemented out of tree.
- PNS pNFS features that are not supported yet (out of tree).
+ NS* Unimplemented optional feature.
Operations
@@ -70,13 +63,13 @@ I | DESTROY_SESSION | REQ | | Section 18.37 |
I | EXCHANGE_ID | REQ | | Section 18.35 |
I | FREE_STATEID | REQ | | Section 18.38 |
| GETATTR | REQ | | Section 18.7 |
-P | GETDEVICEINFO | OPT | pNFS (REQ) | Section 18.40 |
-P | GETDEVICELIST | OPT | pNFS (OPT) | Section 18.41 |
+I | GETDEVICEINFO | OPT | pNFS (REQ) | Section 18.40 |
+NS*| GETDEVICELIST | OPT | pNFS (OPT) | Section 18.41 |
| GETFH | REQ | | Section 18.8 |
NS*| GET_DIR_DELEGATION | OPT | DDELG (REQ) | Section 18.39 |
-P | LAYOUTCOMMIT | OPT | pNFS (REQ) | Section 18.42 |
-P | LAYOUTGET | OPT | pNFS (REQ) | Section 18.43 |
-P | LAYOUTRETURN | OPT | pNFS (REQ) | Section 18.44 |
+I | LAYOUTCOMMIT | OPT | pNFS (REQ) | Section 18.42 |
+I | LAYOUTGET | OPT | pNFS (REQ) | Section 18.43 |
+I | LAYOUTRETURN | OPT | pNFS (REQ) | Section 18.44 |
| LINK | OPT | | Section 18.9 |
| LOCK | REQ | | Section 18.10 |
| LOCKT | REQ | | Section 18.11 |
@@ -122,9 +115,9 @@ Callback Operations
| | MNI | or OPT) | |
+-------------------------+-----------+-------------+---------------+
| CB_GETATTR | OPT | FDELG (REQ) | Section 20.1 |
-P | CB_LAYOUTRECALL | OPT | pNFS (REQ) | Section 20.3 |
+I | CB_LAYOUTRECALL | OPT | pNFS (REQ) | Section 20.3 |
NS*| CB_NOTIFY | OPT | DDELG (REQ) | Section 20.4 |
-P | CB_NOTIFY_DEVICEID | OPT | pNFS (OPT) | Section 20.12 |
+NS*| CB_NOTIFY_DEVICEID | OPT | pNFS (OPT) | Section 20.12 |
NS*| CB_NOTIFY_LOCK | OPT | | Section 20.11 |
NS*| CB_PUSH_DELEG | OPT | FDELG (OPT) | Section 20.5 |
| CB_RECALL | OPT | FDELG, | Section 20.2 |
diff --git a/Documentation/filesystems/nfs/pnfs-block-server.txt b/Documentation/filesystems/nfs/pnfs-block-server.txt
new file mode 100644
index 000000000000..2143673cf154
--- /dev/null
+++ b/Documentation/filesystems/nfs/pnfs-block-server.txt
@@ -0,0 +1,37 @@
+pNFS block layout server user guide
+
+The Linux NFS server now supports the pNFS block layout extension. In this
+case the NFS server acts as Metadata Server (MDS) for pNFS, which in addition
+to handling all the metadata access to the NFS export also hands out layouts
+to the clients to directly access the underlying block devices that are
+shared with the client.
+
+To use pNFS block layouts with with the Linux NFS server the exported file
+system needs to support the pNFS block layouts (currently just XFS), and the
+file system must sit on shared storage (typically iSCSI) that is accessible
+to the clients in addition to the MDS. As of now the file system needs to
+sit directly on the exported volume, striping or concatenation of
+volumes on the MDS and clients is not supported yet.
+
+On the server, pNFS block volume support is automatically if the file system
+support it. On the client make sure the kernel has the CONFIG_PNFS_BLOCK
+option enabled, the blkmapd daemon from nfs-utils is running, and the
+file system is mounted using the NFSv4.1 protocol version (mount -o vers=4.1).
+
+If the nfsd server needs to fence a non-responding client it calls
+/sbin/nfsd-recall-failed with the first argument set to the IP address of
+the client, and the second argument set to the device node without the /dev
+prefix for the file system to be fenced. Below is an example file that shows
+how to translate the device into a serial number from SCSI EVPD 0x80:
+
+cat > /sbin/nfsd-recall-failed << EOF
+#!/bin/sh
+
+CLIENT="$1"
+DEV="/dev/$2"
+EVPD=`sg_inq --page=0x80 ${DEV} | \
+ grep "Unit serial number:" | \
+ awk -F ': ' '{print $2}'`
+
+echo "fencing client ${CLIENT} serial ${EVPD}" >> /var/log/pnfsd-fence.log
+EOF
diff --git a/Documentation/filesystems/nfs/pnfs.txt b/Documentation/filesystems/nfs/pnfs.txt
index adc81a35fe2d..44a9f2493a88 100644
--- a/Documentation/filesystems/nfs/pnfs.txt
+++ b/Documentation/filesystems/nfs/pnfs.txt
@@ -57,15 +57,16 @@ bit is set, preventing any new lsegs from being added.
layout drivers
--------------
-PNFS utilizes what is called layout drivers. The STD defines 3 basic
-layout types: "files" "objects" and "blocks". For each of these types
-there is a layout-driver with a common function-vectors table which
-are called by the nfs-client pnfs-core to implement the different layout
-types.
+PNFS utilizes what is called layout drivers. The STD defines 4 basic
+layout types: "files", "objects", "blocks", and "flexfiles". For each
+of these types there is a layout-driver with a common function-vectors
+table which are called by the nfs-client pnfs-core to implement the
+different layout types.
-Files-layout-driver code is in: fs/nfs/nfs4filelayout.c && nfs4filelayoutdev.c
+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
+Flexfiles-layout-driver code is in: fs/nfs/flexfilelayout/.. directory
objects-layout setup
--------------------
diff --git a/Documentation/filesystems/ocfs2.txt b/Documentation/filesystems/ocfs2.txt
index 7618a287aa41..28f8c08201e2 100644
--- a/Documentation/filesystems/ocfs2.txt
+++ b/Documentation/filesystems/ocfs2.txt
@@ -100,3 +100,7 @@ coherency=full (*) Disallow concurrent O_DIRECT writes, cluster inode
coherency=buffered Allow concurrent O_DIRECT writes without EX lock among
nodes, which gains high performance at risk of getting
stale data on other nodes.
+journal_async_commit Commit block can be written to disk without waiting
+ for descriptor blocks. If enabled older kernels cannot
+ mount the device. This will enable 'journal_checksum'
+ internally.
diff --git a/Documentation/filesystems/overlayfs.txt b/Documentation/filesystems/overlayfs.txt
index a27c950ece61..6db0e5d1da07 100644
--- a/Documentation/filesystems/overlayfs.txt
+++ b/Documentation/filesystems/overlayfs.txt
@@ -159,6 +159,22 @@ overlay filesystem (though an operation on the name of the file such as
rename or unlink will of course be noticed and handled).
+Multiple lower layers
+---------------------
+
+Multiple lower layers can now be given using the the colon (":") as a
+separator character between the directory names. For example:
+
+ mount -t overlay overlay -olowerdir=/lower1:/lower2:/lower3 /merged
+
+As the example shows, "upperdir=" and "workdir=" may be omitted. In
+that case the overlay will be read-only.
+
+The specified lower directories will be stacked beginning from the
+rightmost one and going left. In the above example lower1 will be the
+top, lower2 the middle and lower3 the bottom layer.
+
+
Non-standard behavior
---------------------
@@ -196,3 +212,15 @@ Changes to the underlying filesystems while part of a mounted overlay
filesystem are not allowed. If the underlying filesystem is changed,
the behavior of the overlay is undefined, though it will not result in
a crash or deadlock.
+
+Testsuite
+---------
+
+There's testsuite developed by David Howells at:
+
+ git://git.infradead.org/users/dhowells/unionmount-testsuite.git
+
+Run as root:
+
+ # cd unionmount-testsuite
+ # ./run --ov
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index aae9dd13c91f..a07ba61662ed 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -28,7 +28,7 @@ Table of Contents
1.6 Parallel port info in /proc/parport
1.7 TTY info in /proc/tty
1.8 Miscellaneous kernel statistics in /proc/stat
- 1.9 Ext4 file system parameters
+ 1.9 Ext4 file system parameters
2 Modifying System Parameters
@@ -42,6 +42,7 @@ Table of Contents
3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
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
4 Configuring procfs
4.1 Mount options
@@ -144,6 +145,8 @@ Table 1-1: Process specific entries in /proc
stack Report full stack trace, enable via CONFIG_STACKTRACE
smaps a extension based on maps, showing the memory consumption of
each mapping and flags associated with it
+ numa_maps an extension based on maps, showing the memory locality and
+ binding policy as well as mem usage (in pages) of each mapping.
..............................................................................
For example, to get the status information of a process, all you have to do is
@@ -488,12 +491,47 @@ To clear the bits for the file mapped pages associated with the process
To clear the soft-dirty bit
> echo 4 > /proc/PID/clear_refs
+To reset the peak resident set size ("high water mark") to the process's
+current value:
+ > echo 5 > /proc/PID/clear_refs
+
Any other value written to /proc/PID/clear_refs will have no effect.
The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags
using /proc/kpageflags and number of times a page is mapped using
/proc/kpagecount. For detailed explanation, see Documentation/vm/pagemap.txt.
+The /proc/pid/numa_maps is an extension based on maps, showing the memory
+locality and binding policy, as well as the memory usage (in pages) of
+each mapping. The output follows a general format where mapping details get
+summarized separated by blank spaces, one mapping per each file line:
+
+address policy mapping details
+
+00400000 default file=/usr/local/bin/app mapped=1 active=0 N3=1 kernelpagesize_kB=4
+00600000 default file=/usr/local/bin/app anon=1 dirty=1 N3=1 kernelpagesize_kB=4
+3206000000 default file=/lib64/ld-2.12.so mapped=26 mapmax=6 N0=24 N3=2 kernelpagesize_kB=4
+320621f000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
+3206220000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
+3206221000 default anon=1 dirty=1 N3=1 kernelpagesize_kB=4
+3206800000 default file=/lib64/libc-2.12.so mapped=59 mapmax=21 active=55 N0=41 N3=18 kernelpagesize_kB=4
+320698b000 default file=/lib64/libc-2.12.so
+3206b8a000 default file=/lib64/libc-2.12.so anon=2 dirty=2 N3=2 kernelpagesize_kB=4
+3206b8e000 default file=/lib64/libc-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
+3206b8f000 default anon=3 dirty=3 active=1 N3=3 kernelpagesize_kB=4
+7f4dc10a2000 default anon=3 dirty=3 N3=3 kernelpagesize_kB=4
+7f4dc10b4000 default anon=2 dirty=2 active=1 N3=2 kernelpagesize_kB=4
+7f4dc1200000 default file=/anon_hugepage\040(deleted) huge anon=1 dirty=1 N3=1 kernelpagesize_kB=2048
+7fff335f0000 default stack anon=3 dirty=3 N3=3 kernelpagesize_kB=4
+7fff3369d000 default mapped=1 mapmax=35 active=0 N3=1 kernelpagesize_kB=4
+
+Where:
+"address" is the starting address for the mapping;
+"policy" reports the NUMA memory policy set for the mapping (see vm/numa_memory_policy.txt);
+"mapping details" summarizes mapping data such as mapping type, page usage counters,
+node locality page counters (N0 == node0, N1 == node1, ...) and the kernel page
+size, in KB, that is backing the mapping up.
+
1.2 Kernel data
---------------
@@ -1763,6 +1801,28 @@ pair provide additional information particular to the objects they represent.
with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value'
still exhibits timer's remaining time.
+3.9 /proc/<pid>/map_files - Information about memory mapped files
+---------------------------------------------------------------------
+This directory contains symbolic links which represent memory mapped files
+the process is maintaining. Example output:
+
+ | lr-------- 1 root root 64 Jan 27 11:24 333c600000-333c620000 -> /usr/lib64/ld-2.18.so
+ | lr-------- 1 root root 64 Jan 27 11:24 333c81f000-333c820000 -> /usr/lib64/ld-2.18.so
+ | lr-------- 1 root root 64 Jan 27 11:24 333c820000-333c821000 -> /usr/lib64/ld-2.18.so
+ | ...
+ | lr-------- 1 root root 64 Jan 27 11:24 35d0421000-35d0422000 -> /usr/lib64/libselinux.so.1
+ | lr-------- 1 root root 64 Jan 27 11:24 400000-41a000 -> /usr/bin/ls
+
+The name of a link represents the virtual memory bounds of a mapping, i.e.
+vm_area_struct::vm_start-vm_area_struct::vm_end.
+
+The main purpose of the map_files is to retrieve a set of memory mapped
+files in a fast way instead of parsing /proc/<pid>/maps or
+/proc/<pid>/smaps, both of which contain many more records. At the same
+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.
+
------------------------------------------------------------------------------
Configuring procfs
------------------------------------------------------------------------------
diff --git a/Documentation/filesystems/seq_file.txt b/Documentation/filesystems/seq_file.txt
index b797ed38de46..9de4303201e1 100644
--- a/Documentation/filesystems/seq_file.txt
+++ b/Documentation/filesystems/seq_file.txt
@@ -194,16 +194,16 @@ which is in the string esc will be represented in octal form in the output.
There are also a pair of functions for printing filenames:
- int seq_path(struct seq_file *m, struct path *path, char *esc);
- int seq_path_root(struct seq_file *m, struct path *path,
- struct path *root, char *esc)
+ int seq_path(struct seq_file *m, const struct path *path,
+ const char *esc);
+ int seq_path_root(struct seq_file *m, const struct path *path,
+ const struct path *root, const char *esc)
Here, path indicates the file of interest, and esc is a set of characters
which should be escaped in the output. A call to seq_path() will output
the path relative to the current process's filesystem root. If a different
-root is desired, it can be used with seq_path_root(). Note that, if it
-turns out that path cannot be reached from root, the value of root will be
-changed in seq_file_root() to a root which *does* work.
+root is desired, it can be used with seq_path_root(). If it turns out that
+path cannot be reached from root, seq_path_root() returns SEQ_SKIP.
A function producing complicated output may want to check
bool seq_has_overflowed(struct seq_file *m);
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 43ce0507ee25..966b22829f3b 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -591,8 +591,6 @@ struct address_space_operations {
int (*releasepage) (struct page *, int);
void (*freepage)(struct page *);
ssize_t (*direct_IO)(int, struct kiocb *, struct iov_iter *iter, loff_t offset);
- struct page* (*get_xip_page)(struct address_space *, sector_t,
- int);
/* migrate the contents of a page to the specified target */
int (*migratepage) (struct page *, struct page *);
int (*launder_page) (struct page *);
@@ -748,11 +746,6 @@ struct address_space_operations {
and transfer data directly between the storage and the
application's address space.
- get_xip_page: called by the VM to translate a block number to a page.
- The page is valid until the corresponding filesystem is unmounted.
- Filesystems that want to use execute-in-place (XIP) need to implement
- it. An example implementation can be found in fs/ext2/xip.c.
-
migrate_page: This is used to compact the physical memory usage.
If the VM wants to relocate a page (maybe off a memory card
that is signalling imminent failure) it will pass a new page
diff --git a/Documentation/filesystems/xfs.txt b/Documentation/filesystems/xfs.txt
index 5be51fd888bd..0bfafe108357 100644
--- a/Documentation/filesystems/xfs.txt
+++ b/Documentation/filesystems/xfs.txt
@@ -287,9 +287,9 @@ The following sysctls are available for the XFS filesystem:
XFS_ERRLEVEL_LOW: 1
XFS_ERRLEVEL_HIGH: 5
- fs.xfs.panic_mask (Min: 0 Default: 0 Max: 127)
+ fs.xfs.panic_mask (Min: 0 Default: 0 Max: 255)
Causes certain error conditions to call BUG(). Value is a bitmask;
- AND together the tags which represent errors which should cause panics:
+ OR together the tags which represent errors which should cause panics:
XFS_NO_PTAG 0
XFS_PTAG_IFLUSH 0x00000001
@@ -299,6 +299,7 @@ The following sysctls are available for the XFS filesystem:
XFS_PTAG_SHUTDOWN_CORRUPT 0x00000010
XFS_PTAG_SHUTDOWN_IOERROR 0x00000020
XFS_PTAG_SHUTDOWN_LOGERROR 0x00000040
+ XFS_PTAG_FSBLOCK_ZERO 0x00000080
This option is intended for debugging only.
@@ -348,16 +349,13 @@ The following sysctls are available for the XFS filesystem:
Deprecated Sysctls
==================
- fs.xfs.xfsbufd_centisecs (Min: 50 Default: 100 Max: 3000)
- Dirty metadata is now tracked by the log subsystem and
- flushing is driven by log space and idling demands. The
- xfsbufd no longer exists, so this syctl does nothing.
+None at present.
- Due for removal in 3.14.
- fs.xfs.age_buffer_centisecs (Min: 100 Default: 1500 Max: 720000)
- Dirty metadata is now tracked by the log subsystem and
- flushing is driven by log space and idling demands. The
- xfsbufd no longer exists, so this syctl does nothing.
+Removed Sysctls
+===============
- Due for removal in 3.14.
+ Name Removed
+ ---- -------
+ fs.xfs.xfsbufd_centisec v3.20
+ fs.xfs.age_buffer_centisecs v3.20
diff --git a/Documentation/filesystems/xip.txt b/Documentation/filesystems/xip.txt
deleted file mode 100644
index 0466ee569278..000000000000
--- a/Documentation/filesystems/xip.txt
+++ /dev/null
@@ -1,68 +0,0 @@
-Execute-in-place for file mappings
-----------------------------------
-
-Motivation
-----------
-File mappings are performed by mapping page cache pages to userspace. In
-addition, read&write type file operations also transfer data from/to the page
-cache.
-
-For memory backed storage devices that use the block device interface, the page
-cache pages are in fact copies of the original storage. Various approaches
-exist to work around the need for an extra copy. The ramdisk driver for example
-does read the data into the page cache, keeps a reference, and discards the
-original data behind later on.
-
-Execute-in-place solves this issue the other way around: instead of keeping
-data in the page cache, the need to have a page cache copy is eliminated
-completely. With execute-in-place, read&write type operations are performed
-directly from/to the memory backed storage device. For file mappings, the
-storage device itself is mapped directly into userspace.
-
-This implementation was initially written for shared memory segments between
-different virtual machines on s390 hardware to allow multiple machines to
-share the same binaries and libraries.
-
-Implementation
---------------
-Execute-in-place is implemented in three steps: block device operation,
-address space operation, and file operations.
-
-A block device operation named direct_access is used to retrieve a
-reference (pointer) to a block on-disk. The reference is supposed to be
-cpu-addressable, physical address and remain valid until the release operation
-is performed. A struct block_device reference is used to address the device,
-and a sector_t argument is used to identify the individual block. As an
-alternative, memory technology devices can be used for this.
-
-The block device operation is optional, these block devices support it as of
-today:
-- dcssblk: s390 dcss block device driver
-
-An address space operation named get_xip_mem is used to retrieve references
-to a page frame number and a kernel address. To obtain these values a reference
-to an address_space is provided. This function assigns values to the kmem and
-pfn parameters. The third argument indicates whether the function should allocate
-blocks if needed.
-
-This address space operation is mutually exclusive with readpage&writepage that
-do page cache read/write operations.
-The following filesystems support it as of today:
-- ext2: the second extended filesystem, see Documentation/filesystems/ext2.txt
-
-A set of file operations that do utilize get_xip_page can be found in
-mm/filemap_xip.c . The following file operation implementations are provided:
-- aio_read/aio_write
-- readv/writev
-- sendfile
-
-The generic file operations do_sync_read/do_sync_write can be used to implement
-classic synchronous IO calls.
-
-Shortcomings
-------------
-This implementation is limited to storage devices that are cpu addressable at
-all times (no highmem or such). It works well on rom/ram, but enhancements are
-needed to make it work with flash in read+write mode.
-Putting the Linux kernel and/or its modules on a xip filesystem does not mean
-they are not copied.