1. 06 10月, 2010 2 次提交
  2. 23 9月, 2010 1 次提交
  3. 22 5月, 2010 1 次提交
  4. 21 11月, 2009 1 次提交
  5. 07 10月, 2009 1 次提交
  6. 07 4月, 2009 1 次提交
  7. 03 4月, 2009 2 次提交
    • D
      CacheFiles: A cache that backs onto a mounted filesystem · 9ae326a6
      David Howells 提交于
      Add an FS-Cache cache-backend that permits a mounted filesystem to be used as a
      backing store for the cache.
      
      CacheFiles uses a userspace daemon to do some of the cache management - such as
      reaping stale nodes and culling.  This is called cachefilesd and lives in
      /sbin.  The source for the daemon can be downloaded from:
      
      	http://people.redhat.com/~dhowells/cachefs/cachefilesd.c
      
      And an example configuration from:
      
      	http://people.redhat.com/~dhowells/cachefs/cachefilesd.conf
      
      The filesystem and data integrity of the cache are only as good as those of the
      filesystem providing the backing services.  Note that CacheFiles does not
      attempt to journal anything since the journalling interfaces of the various
      filesystems are very specific in nature.
      
      CacheFiles creates a misc character device - "/dev/cachefiles" - that is used
      to communication with the daemon.  Only one thing may have this open at once,
      and whilst it is open, a cache is at least partially in existence.  The daemon
      opens this and sends commands down it to control the cache.
      
      CacheFiles is currently limited to a single cache.
      
      CacheFiles attempts to maintain at least a certain percentage of free space on
      the filesystem, shrinking the cache by culling the objects it contains to make
      space if necessary - see the "Cache Culling" section.  This means it can be
      placed on the same medium as a live set of data, and will expand to make use of
      spare space and automatically contract when the set of data requires more
      space.
      
      ============
      REQUIREMENTS
      ============
      
      The use of CacheFiles and its daemon requires the following features to be
      available in the system and in the cache filesystem:
      
      	- dnotify.
      
      	- extended attributes (xattrs).
      
      	- openat() and friends.
      
      	- bmap() support on files in the filesystem (FIBMAP ioctl).
      
      	- The use of bmap() to detect a partial page at the end of the file.
      
      It is strongly recommended that the "dir_index" option is enabled on Ext3
      filesystems being used as a cache.
      
      =============
      CONFIGURATION
      =============
      
      The cache is configured by a script in /etc/cachefilesd.conf.  These commands
      set up cache ready for use.  The following script commands are available:
      
       (*) brun <N>%
       (*) bcull <N>%
       (*) bstop <N>%
       (*) frun <N>%
       (*) fcull <N>%
       (*) fstop <N>%
      
      	Configure the culling limits.  Optional.  See the section on culling
      	The defaults are 7% (run), 5% (cull) and 1% (stop) respectively.
      
      	The commands beginning with a 'b' are file space (block) limits, those
      	beginning with an 'f' are file count limits.
      
       (*) dir <path>
      
      	Specify the directory containing the root of the cache.  Mandatory.
      
       (*) tag <name>
      
      	Specify a tag to FS-Cache to use in distinguishing multiple caches.
      	Optional.  The default is "CacheFiles".
      
       (*) debug <mask>
      
      	Specify a numeric bitmask to control debugging in the kernel module.
      	Optional.  The default is zero (all off).  The following values can be
      	OR'd into the mask to collect various information:
      
      		1	Turn on trace of function entry (_enter() macros)
      		2	Turn on trace of function exit (_leave() macros)
      		4	Turn on trace of internal debug points (_debug())
      
      	This mask can also be set through sysfs, eg:
      
      		echo 5 >/sys/modules/cachefiles/parameters/debug
      
      ==================
      STARTING THE CACHE
      ==================
      
      The cache is started by running the daemon.  The daemon opens the cache device,
      configures the cache and tells it to begin caching.  At that point the cache
      binds to fscache and the cache becomes live.
      
      The daemon is run as follows:
      
      	/sbin/cachefilesd [-d]* [-s] [-n] [-f <configfile>]
      
      The flags are:
      
       (*) -d
      
      	Increase the debugging level.  This can be specified multiple times and
      	is cumulative with itself.
      
       (*) -s
      
      	Send messages to stderr instead of syslog.
      
       (*) -n
      
      	Don't daemonise and go into background.
      
       (*) -f <configfile>
      
      	Use an alternative configuration file rather than the default one.
      
      ===============
      THINGS TO AVOID
      ===============
      
      Do not mount other things within the cache as this will cause problems.  The
      kernel module contains its own very cut-down path walking facility that ignores
      mountpoints, but the daemon can't avoid them.
      
      Do not create, rename or unlink files and directories in the cache whilst the
      cache is active, as this may cause the state to become uncertain.
      
      Renaming files in the cache might make objects appear to be other objects (the
      filename is part of the lookup key).
      
      Do not change or remove the extended attributes attached to cache files by the
      cache as this will cause the cache state management to get confused.
      
      Do not create files or directories in the cache, lest the cache get confused or
      serve incorrect data.
      
      Do not chmod files in the cache.  The module creates things with minimal
      permissions to prevent random users being able to access them directly.
      
      =============
      CACHE CULLING
      =============
      
      The cache may need culling occasionally to make space.  This involves
      discarding objects from the cache that have been used less recently than
      anything else.  Culling is based on the access time of data objects.  Empty
      directories are culled if not in use.
      
      Cache culling is done on the basis of the percentage of blocks and the
      percentage of files available in the underlying filesystem.  There are six
      "limits":
      
       (*) brun
       (*) frun
      
           If the amount of free space and the number of available files in the cache
           rises above both these limits, then culling is turned off.
      
       (*) bcull
       (*) fcull
      
           If the amount of available space or the number of available files in the
           cache falls below either of these limits, then culling is started.
      
       (*) bstop
       (*) fstop
      
           If the amount of available space or the number of available files in the
           cache falls below either of these limits, then no further allocation of
           disk space or files is permitted until culling has raised things above
           these limits again.
      
      These must be configured thusly:
      
      	0 <= bstop < bcull < brun < 100
      	0 <= fstop < fcull < frun < 100
      
      Note that these are percentages of available space and available files, and do
      _not_ appear as 100 minus the percentage displayed by the "df" program.
      
      The userspace daemon scans the cache to build up a table of cullable objects.
      These are then culled in least recently used order.  A new scan of the cache is
      started as soon as space is made in the table.  Objects will be skipped if
      their atimes have changed or if the kernel module says it is still using them.
      
      ===============
      CACHE STRUCTURE
      ===============
      
      The CacheFiles module will create two directories in the directory it was
      given:
      
       (*) cache/
      
       (*) graveyard/
      
      The active cache objects all reside in the first directory.  The CacheFiles
      kernel module moves any retired or culled objects that it can't simply unlink
      to the graveyard from which the daemon will actually delete them.
      
      The daemon uses dnotify to monitor the graveyard directory, and will delete
      anything that appears therein.
      
      The module represents index objects as directories with the filename "I..." or
      "J...".  Note that the "cache/" directory is itself a special index.
      
      Data objects are represented as files if they have no children, or directories
      if they do.  Their filenames all begin "D..." or "E...".  If represented as a
      directory, data objects will have a file in the directory called "data" that
      actually holds the data.
      
      Special objects are similar to data objects, except their filenames begin
      "S..." or "T...".
      
      If an object has children, then it will be represented as a directory.
      Immediately in the representative directory are a collection of directories
      named for hash values of the child object keys with an '@' prepended.  Into
      this directory, if possible, will be placed the representations of the child
      objects:
      
      	INDEX     INDEX      INDEX                             DATA FILES
      	========= ========== ================================= ================
      	cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400
      	cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...DB1ry
      	cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...N22ry
      	cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...FP1ry
      
      If the key is so long that it exceeds NAME_MAX with the decorations added on to
      it, then it will be cut into pieces, the first few of which will be used to
      make a nest of directories, and the last one of which will be the objects
      inside the last directory.  The names of the intermediate directories will have
      '+' prepended:
      
      	J1223/@23/+xy...z/+kl...m/Epqr
      
      Note that keys are raw data, and not only may they exceed NAME_MAX in size,
      they may also contain things like '/' and NUL characters, and so they may not
      be suitable for turning directly into a filename.
      
      To handle this, CacheFiles will use a suitably printable filename directly and
      "base-64" encode ones that aren't directly suitable.  The two versions of
      object filenames indicate the encoding:
      
      	OBJECT TYPE	PRINTABLE	ENCODED
      	===============	===============	===============
      	Index		"I..."		"J..."
      	Data		"D..."		"E..."
      	Special		"S..."		"T..."
      
      Intermediate directories are always "@" or "+" as appropriate.
      
      Each object in the cache has an extended attribute label that holds the object
      type ID (required to distinguish special objects) and the auxiliary data from
      the netfs.  The latter is used to detect stale objects in the cache and update
      or retire them.
      
      Note that CacheFiles will erase from the cache any file it doesn't recognise or
      any file of an incorrect type (such as a FIFO file or a device file).
      
      ==========================
      SECURITY MODEL AND SELINUX
      ==========================
      
      CacheFiles is implemented to deal properly with the LSM security features of
      the Linux kernel and the SELinux facility.
      
      One of the problems that CacheFiles faces is that it is generally acting on
      behalf of a process, and running in that process's context, and that includes a
      security context that is not appropriate for accessing the cache - either
      because the files in the cache are inaccessible to that process, or because if
      the process creates a file in the cache, that file may be inaccessible to other
      processes.
      
      The way CacheFiles works is to temporarily change the security context (fsuid,
      fsgid and actor security label) that the process acts as - without changing the
      security context of the process when it the target of an operation performed by
      some other process (so signalling and suchlike still work correctly).
      
      When the CacheFiles module is asked to bind to its cache, it:
      
       (1) Finds the security label attached to the root cache directory and uses
           that as the security label with which it will create files.  By default,
           this is:
      
      	cachefiles_var_t
      
       (2) Finds the security label of the process which issued the bind request
           (presumed to be the cachefilesd daemon), which by default will be:
      
      	cachefilesd_t
      
           and asks LSM to supply a security ID as which it should act given the
           daemon's label.  By default, this will be:
      
      	cachefiles_kernel_t
      
           SELinux transitions the daemon's security ID to the module's security ID
           based on a rule of this form in the policy.
      
      	type_transition <daemon's-ID> kernel_t : process <module's-ID>;
      
           For instance:
      
      	type_transition cachefilesd_t kernel_t : process cachefiles_kernel_t;
      
      The module's security ID gives it permission to create, move and remove files
      and directories in the cache, to find and access directories and files in the
      cache, to set and access extended attributes on cache objects, and to read and
      write files in the cache.
      
      The daemon's security ID gives it only a very restricted set of permissions: it
      may scan directories, stat files and erase files and directories.  It may
      not read or write files in the cache, and so it is precluded from accessing the
      data cached therein; nor is it permitted to create new files in the cache.
      
      There are policy source files available in:
      
      	http://people.redhat.com/~dhowells/fscache/cachefilesd-0.8.tar.bz2
      
      and later versions.  In that tarball, see the files:
      
      	cachefilesd.te
      	cachefilesd.fc
      	cachefilesd.if
      
      They are built and installed directly by the RPM.
      
      If a non-RPM based system is being used, then copy the above files to their own
      directory and run:
      
      	make -f /usr/share/selinux/devel/Makefile
      	semodule -i cachefilesd.pp
      
      You will need checkpolicy and selinux-policy-devel installed prior to the
      build.
      
      By default, the cache is located in /var/fscache, but if it is desirable that
      it should be elsewhere, than either the above policy files must be altered, or
      an auxiliary policy must be installed to label the alternate location of the
      cache.
      
      For instructions on how to add an auxiliary policy to enable the cache to be
      located elsewhere when SELinux is in enforcing mode, please see:
      
      	/usr/share/doc/cachefilesd-*/move-cache.txt
      
      When the cachefilesd rpm is installed; alternatively, the document can be found
      in the sources.
      
      ==================
      A NOTE ON SECURITY
      ==================
      
      CacheFiles makes use of the split security in the task_struct.  It allocates
      its own task_security structure, and redirects current->act_as to point to it
      when it acts on behalf of another process, in that process's context.
      
      The reason it does this is that it calls vfs_mkdir() and suchlike rather than
      bypassing security and calling inode ops directly.  Therefore the VFS and LSM
      may deny the CacheFiles access to the cache data because under some
      circumstances the caching code is running in the security context of whatever
      process issued the original syscall on the netfs.
      
      Furthermore, should CacheFiles create a file or directory, the security
      parameters with that object is created (UID, GID, security label) would be
      derived from that process that issued the system call, thus potentially
      preventing other processes from accessing the cache - including CacheFiles's
      cache management daemon (cachefilesd).
      
      What is required is to temporarily override the security of the process that
      issued the system call.  We can't, however, just do an in-place change of the
      security data as that affects the process as an object, not just as a subject.
      This means it may lose signals or ptrace events for example, and affects what
      the process looks like in /proc.
      
      So CacheFiles makes use of a logical split in the security between the
      objective security (task->sec) and the subjective security (task->act_as).  The
      objective security holds the intrinsic security properties of a process and is
      never overridden.  This is what appears in /proc, and is what is used when a
      process is the target of an operation by some other process (SIGKILL for
      example).
      
      The subjective security holds the active security properties of a process, and
      may be overridden.  This is not seen externally, and is used whan a process
      acts upon another object, for example SIGKILLing another process or opening a
      file.
      
      LSM hooks exist that allow SELinux (or Smack or whatever) to reject a request
      for CacheFiles to run in a context of a specific security label, or to create
      files and directories with another security label.
      
      This documentation is added by the patch to:
      
      	Documentation/filesystems/caching/cachefiles.txt
      Signed-Off-By: NDavid Howells <dhowells@redhat.com>
      Acked-by: NSteve Dickson <steved@redhat.com>
      Acked-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
      Acked-by: NAl Viro <viro@zeniv.linux.org.uk>
      Tested-by: NDaire Byrne <Daire.Byrne@framestore.com>
      9ae326a6
    • D
      FS-Cache: Add main configuration option, module entry points and debugging · 06b3db1b
      David Howells 提交于
      Add the main configuration option, allowing FS-Cache to be selected; the
      module entry and exit functions and the debugging stuff used by these patches.
      
      The two configuration options added are:
      
      	CONFIG_FSCACHE
      	CONFIG_FSCACHE_DEBUG
      
      The first enables the facility, and the second makes the debugging statements
      enableable through the "debug" module parameter.  The value of this parameter
      is a bitmask as described in:
      
      	Documentation/filesystems/caching/fscache.txt
      
      The module can be loaded at this point, but all it will do at this point in
      the patch series is to start up the slow work facility and shut it down again.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      Acked-by: NSteve Dickson <steved@redhat.com>
      Acked-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
      Acked-by: NAl Viro <viro@zeniv.linux.org.uk>
      Tested-by: NDaire Byrne <Daire.Byrne@framestore.com>
      06b3db1b
  8. 01 4月, 2009 2 次提交
  9. 26 3月, 2009 1 次提交
  10. 28 2月, 2009 1 次提交
    • T
      ext4: Reorder fs/Makefile so that ext2 root fs's are mounted using ext2 · d8ae4601
      Theodore Ts'o 提交于
      In fs/Makefile, ext3 was placed before ext2 so that a root filesystem
      that possessed a journal, it would be mounted as ext3 instead of ext2.
      This was necessary because a cleanly unmounted ext3 filesystem was
      fully backwards compatible with ext2, and could be mounted by ext2 ---
      but it was desirable that it be mounted with ext3 so that the
      journaling would be enabled.
      
      The ext4 filesystem supports new incompatible features, so there is no
      danger of an ext4 filesystem being mistaken for an ext2 filesystem.
      At that point, the relative ordering of ext4 with respect to ext2
      didn't matter until ext4 gained the ability to mount filesystems
      without a journal starting in 2.6.29-rc1.  Now that this is the case,
      given that ext4 is before ext2, it means that root filesystems that
      were using the plain-jane ext2 format are getting mounted using the
      ext4 filesystem driver, which is a change in behavior which could be
      surprising to users.
      
      It's doubtful that there are that many ext2-only root filesystem users
      that would also have ext4 compiled into the kernel, but to adhere to
      the principle of least surprise, the correct ordering in fs/Makefile
      is ext3, followed by ext2, and finally ext4.
      Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
      d8ae4601
  11. 06 1月, 2009 1 次提交
    • J
      quota: Split off quota tree handling into a separate file · 1ccd14b9
      Jan Kara 提交于
      There is going to be a new version of quota format having 64-bit
      quota limits and a new quota format for OCFS2. They are both
      going to use the same tree structure as VFSv0 quota format. So
      split out tree handling into a separate file and make size of
      leaf blocks, amount of space usable in each block (needed for
      checksumming) and structures contained in them configurable
      so that the code can be shared.
      Signed-off-by: NJan Kara <jack@suse.cz>
      Signed-off-by: NMark Fasheh <mfasheh@suse.com>
      1ccd14b9
  12. 05 1月, 2009 1 次提交
  13. 01 1月, 2009 1 次提交
  14. 07 11月, 2008 1 次提交
  15. 17 10月, 2008 1 次提交
  16. 18 10月, 2008 1 次提交
  17. 11 10月, 2008 1 次提交
  18. 30 9月, 2008 1 次提交
    • T
      Configure out file locking features · bfcd17a6
      Thomas Petazzoni 提交于
      This patch adds the CONFIG_FILE_LOCKING option which allows to remove
      support for advisory locks. With this patch enabled, the flock()
      system call, the F_GETLK, F_SETLK and F_SETLKW operations of fcntl()
      and NFS support are disabled. These features are not necessarly needed
      on embedded systems. It allows to save ~11 Kb of kernel code and data:
      
         text          data     bss     dec     hex filename
      1125436        118764  212992 1457192  163c28 vmlinux.old
      1114299        118564  212992 1445855  160fdf vmlinux
       -11137    -200       0  -11337   -2C49 +/-
      
      This patch has originally been written by Matt Mackall
      <mpm@selenic.com>, and is part of the Linux Tiny project.
      Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
      Signed-off-by: NMatt Mackall <mpm@selenic.com>
      Cc: matthew@wil.cx
      Cc: linux-fsdevel@vger.kernel.org
      Cc: mpm@selenic.com
      Cc: akpm@linux-foundation.org
      Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
      bfcd17a6
  19. 26 9月, 2008 1 次提交
  20. 27 7月, 2008 1 次提交
  21. 15 7月, 2008 1 次提交
  22. 03 7月, 2008 1 次提交
  23. 30 1月, 2008 1 次提交
  24. 17 10月, 2007 1 次提交
  25. 11 5月, 2007 4 次提交
    • D
      signal/timer/event: eventfd core · e1ad7468
      Davide Libenzi 提交于
      This is a very simple and light file descriptor, that can be used as event
      wait/dispatch by userspace (both wait and dispatch) and by the kernel
      (dispatch only).  It can be used instead of pipe(2) in all cases where those
      would simply be used to signal events.  Their kernel overhead is much lower
      than pipes, and they do not consume two fds.  When used in the kernel, it can
      offer an fd-bridge to enable, for example, functionalities like KAIO or
      syslets/threadlets to signal to an fd the completion of certain operations.
      But more in general, an eventfd can be used by the kernel to signal readiness,
      in a POSIX poll/select way, of interfaces that would otherwise be incompatible
      with it.  The API is:
      
      int eventfd(unsigned int count);
      
      The eventfd API accepts an initial "count" parameter, and returns an eventfd
      fd.  It supports poll(2) (POLLIN, POLLOUT, POLLERR), read(2) and write(2).
      
      The POLLIN flag is raised when the internal counter is greater than zero.
      
      The POLLOUT flag is raised when at least a value of "1" can be written to the
      internal counter.
      
      The POLLERR flag is raised when an overflow in the counter value is detected.
      
      The write(2) operation can never overflow the counter, since it blocks (unless
      O_NONBLOCK is set, in which case -EAGAIN is returned).
      
      But the eventfd_signal() function can do it, since it's supposed to not sleep
      during its operation.
      
      The read(2) function reads the __u64 counter value, and reset the internal
      value to zero.  If the value read is equal to (__u64) -1, an overflow happened
      on the internal counter (due to 2^64 eventfd_signal() posts that has never
      been retired - unlickely, but possible).
      
      The write(2) call writes an __u64 count value, and adds it to the current
      counter.  The eventfd fd supports O_NONBLOCK also.
      
      On the kernel side, we have:
      
      struct file *eventfd_fget(int fd);
      int eventfd_signal(struct file *file, unsigned int n);
      
      The eventfd_fget() should be called to get a struct file* from an eventfd fd
      (this is an fget() + check of f_op being an eventfd fops pointer).
      
      The kernel can then call eventfd_signal() every time it wants to post an event
      to userspace.  The eventfd_signal() function can be called from any context.
      An eventfd() simple test and bench is available here:
      
      http://www.xmailserver.org/eventfd-bench.c
      
      This is the eventfd-based version of pipetest-4 (pipe(2) based):
      
      http://www.xmailserver.org/pipetest-4.c
      
      Not that performance matters much in the eventfd case, but eventfd-bench
      shows almost as double as performance than pipetest-4.
      
      [akpm@linux-foundation.org: fix i386 build]
      [akpm@linux-foundation.org: add sys_eventfd to sys_ni.c]
      Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e1ad7468
    • D
      signal/timer/event: timerfd core · b215e283
      Davide Libenzi 提交于
      This patch introduces a new system call for timers events delivered though
      file descriptors.  This allows timer event to be used with standard POSIX
      poll(2), select(2) and read(2).  As a consequence of supporting the Linux
      f_op->poll subsystem, they can be used with epoll(2) too.
      
      The system call is defined as:
      
      int timerfd(int ufd, int clockid, int flags, const struct itimerspec *utmr);
      
      The "ufd" parameter allows for re-use (re-programming) of an existing timerfd
      w/out going through the close/open cycle (same as signalfd).  If "ufd" is -1,
      s new file descriptor will be created, otherwise the existing "ufd" will be
      re-programmed.
      
      The "clockid" parameter is either CLOCK_MONOTONIC or CLOCK_REALTIME.  The time
      specified in the "utmr->it_value" parameter is the expiry time for the timer.
      
      If the TFD_TIMER_ABSTIME flag is set in "flags", this is an absolute time,
      otherwise it's a relative time.
      
      If the time specified in the "utmr->it_interval" is not zero (.tv_sec == 0,
      tv_nsec == 0), this is the period at which the following ticks should be
      generated.
      
      The "utmr->it_interval" should be set to zero if only one tick is requested.
      Setting the "utmr->it_value" to zero will disable the timer, or will create a
      timerfd without the timer enabled.
      
      The function returns the new (or same, in case "ufd" is a valid timerfd
      descriptor) file, or -1 in case of error.
      
      As stated before, the timerfd file descriptor supports poll(2), select(2) and
      epoll(2).  When a timer event happened on the timerfd, a POLLIN mask will be
      returned.
      
      The read(2) call can be used, and it will return a u32 variable holding the
      number of "ticks" that happened on the interface since the last call to
      read(2).  The read(2) call supportes the O_NONBLOCK flag too, and EAGAIN will
      be returned if no ticks happened.
      
      A quick test program, shows timerfd working correctly on my amd64 box:
      
      http://www.xmailserver.org/timerfd-test.c
      
      [akpm@linux-foundation.org: add sys_timerfd to sys_ni.c]
      Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b215e283
    • D
      signal/timer/event: signalfd core · fba2afaa
      Davide Libenzi 提交于
      This patch series implements the new signalfd() system call.
      
      I took part of the original Linus code (and you know how badly it can be
      broken :), and I added even more breakage ;) Signals are fetched from the same
      signal queue used by the process, so signalfd will compete with standard
      kernel delivery in dequeue_signal().  If you want to reliably fetch signals on
      the signalfd file, you need to block them with sigprocmask(SIG_BLOCK).  This
      seems to be working fine on my Dual Opteron machine.  I made a quick test
      program for it:
      
      http://www.xmailserver.org/signafd-test.c
      
      The signalfd() system call implements signal delivery into a file descriptor
      receiver.  The signalfd file descriptor if created with the following API:
      
      int signalfd(int ufd, const sigset_t *mask, size_t masksize);
      
      The "ufd" parameter allows to change an existing signalfd sigmask, w/out going
      to close/create cycle (Linus idea).  Use "ufd" == -1 if you want a brand new
      signalfd file.
      
      The "mask" allows to specify the signal mask of signals that we are interested
      in.  The "masksize" parameter is the size of "mask".
      
      The signalfd fd supports the poll(2) and read(2) system calls.  The poll(2)
      will return POLLIN when signals are available to be dequeued.  As a direct
      consequence of supporting the Linux poll subsystem, the signalfd fd can use
      used together with epoll(2) too.
      
      The read(2) system call will return a "struct signalfd_siginfo" structure in
      the userspace supplied buffer.  The return value is the number of bytes copied
      in the supplied buffer, or -1 in case of error.  The read(2) call can also
      return 0, in case the sighand structure to which the signalfd was attached,
      has been orphaned.  The O_NONBLOCK flag is also supported, and read(2) will
      return -EAGAIN in case no signal is available.
      
      If the size of the buffer passed to read(2) is lower than sizeof(struct
      signalfd_siginfo), -EINVAL is returned.  A read from the signalfd can also
      return -ERESTARTSYS in case a signal hits the process.  The format of the
      struct signalfd_siginfo is, and the valid fields depends of the (->code &
      __SI_MASK) value, in the same way a struct siginfo would:
      
      struct signalfd_siginfo {
      	__u32 signo;	/* si_signo */
      	__s32 err;	/* si_errno */
      	__s32 code;	/* si_code */
      	__u32 pid;	/* si_pid */
      	__u32 uid;	/* si_uid */
      	__s32 fd;	/* si_fd */
      	__u32 tid;	/* si_fd */
      	__u32 band;	/* si_band */
      	__u32 overrun;	/* si_overrun */
      	__u32 trapno;	/* si_trapno */
      	__s32 status;	/* si_status */
      	__s32 svint;	/* si_int */
      	__u64 svptr;	/* si_ptr */
      	__u64 utime;	/* si_utime */
      	__u64 stime;	/* si_stime */
      	__u64 addr;	/* si_addr */
      };
      
      [akpm@linux-foundation.org: fix signalfd_copyinfo() on i386]
      Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      fba2afaa
    • D
      signal/timer/event fds: anonymous inode source · 5dc8bf81
      Davide Libenzi 提交于
      This patch add an anonymous inode source, to be used for files that need
      and inode only in order to create a file*. We do not care of having an
      inode for each file, and we do not even care of having different names in
      the associated dentries (dentry names will be same for classes of file*).
      This allow code reuse, and will be used by epoll, signalfd and timerfd
      (and whatever else there'll be).
      Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5dc8bf81
  26. 18 2月, 2007 1 次提交
  27. 09 12月, 2006 1 次提交
  28. 12 10月, 2006 2 次提交
  29. 04 10月, 2006 1 次提交
  30. 01 10月, 2006 2 次提交
    • A
      [PATCH] Create fs/utimes.c · 82b0547c
      Alexey Dobriyan 提交于
      * fs/open.c is getting bit crowdy
      * preparation to lutimes(2)
      Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      82b0547c
    • D
      [PATCH] BLOCK: Make it possible to disable the block layer [try #6] · 9361401e
      David Howells 提交于
      Make it possible to disable the block layer.  Not all embedded devices require
      it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require
      the block layer to be present.
      
      This patch does the following:
      
       (*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev
           support.
      
       (*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls
           an item that uses the block layer.  This includes:
      
           (*) Block I/O tracing.
      
           (*) Disk partition code.
      
           (*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS.
      
           (*) The SCSI layer.  As far as I can tell, even SCSI chardevs use the
           	 block layer to do scheduling.  Some drivers that use SCSI facilities -
           	 such as USB storage - end up disabled indirectly from this.
      
           (*) Various block-based device drivers, such as IDE and the old CDROM
           	 drivers.
      
           (*) MTD blockdev handling and FTL.
      
           (*) JFFS - which uses set_bdev_super(), something it could avoid doing by
           	 taking a leaf out of JFFS2's book.
      
       (*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and
           linux/elevator.h contingent on CONFIG_BLOCK being set.  sector_div() is,
           however, still used in places, and so is still available.
      
       (*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and
           parts of linux/fs.h.
      
       (*) Makes a number of files in fs/ contingent on CONFIG_BLOCK.
      
       (*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK.
      
       (*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK
           is not enabled.
      
       (*) fs/no-block.c is created to hold out-of-line stubs and things that are
           required when CONFIG_BLOCK is not set:
      
           (*) Default blockdev file operations (to give error ENODEV on opening).
      
       (*) Makes some /proc changes:
      
           (*) /proc/devices does not list any blockdevs.
      
           (*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK.
      
       (*) Makes some compat ioctl handling contingent on CONFIG_BLOCK.
      
       (*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if
           given command other than Q_SYNC or if a special device is specified.
      
       (*) In init/do_mounts.c, no reference is made to the blockdev routines if
           CONFIG_BLOCK is not defined.  This does not prohibit NFS roots or JFFS2.
      
       (*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return
           error ENOSYS by way of cond_syscall if so).
      
       (*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if
           CONFIG_BLOCK is not set, since they can't then happen.
      Signed-Off-By: NDavid Howells <dhowells@redhat.com>
      Signed-off-by: NJens Axboe <axboe@kernel.dk>
      9361401e
  31. 30 9月, 2006 1 次提交
    • A
      [PATCH] Generic infrastructure for acls · f0c8bd16
      Andreas Gruenbacher 提交于
      The patches solve the following problem: We want to grant access to devices
      based on who is logged in from where, etc.  This includes switching back and
      forth between multiple user sessions, etc.
      
      Using ACLs to define device access for logged-in users gives us all the
      flexibility we need in order to fully solve the problem.
      
      Device special files nowadays usually live on tmpfs, hence tmpfs ACLs.
      
      Different distros have come up with solutions that solve the problem to
      different degrees: SUSE uses a resource manager which tracks login sessions
      and sets ACLs on device inodes as appropriate.  RedHat uses pam_console, which
      changes the primary file ownership to the logged-in user.  Others use a set of
      groups that users must be in in order to be granted the appropriate accesses.
      
      The freedesktop.org project plans to implement a combination of a
      console-tracker and a HAL-device-list based solution to grant access to
      devices to users, and more distros will likely follow this approach.
      
      These patches have first been posted here on 2 February 2005, and again
      on 8 January 2006. We have been shipping them in SLES9 and SLES10 with
      no problems reported.  The previous submission is archived here:
      
         http://lkml.org/lkml/2006/1/8/229
         http://lkml.org/lkml/2006/1/8/230
         http://lkml.org/lkml/2006/1/8/231
      
      This patch:
      
      Add some infrastructure for access control lists on in-memory
      filesystems such as tmpfs.
      Signed-off-by: NAndreas Gruenbacher <agruen@suse.de>
      Cc: Hugh Dickins <hugh@veritas.com>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      f0c8bd16
  32. 27 6月, 2006 1 次提交