Eric Lee / smarc-fsl-linux-kernel

21 May, 2019

1 commit

  • 457c89965   treewide: Add SPDX license identifier for missed files ... Browse Code »

    Add SPDX license identifiers to all files which:

    - Have no license information of any form

    - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
    initial scan/conversion to ignore the file

    These files fall under the project license, GPL v2 only. The resulting SPDX
    license identifier is:

    GPL-2.0-only

    Signed-off-by: Thomas Gleixner
    Signed-off-by: Greg Kroah-Hartman

    Thomas Gleixner
     

21 Feb, 2019

1 commit

29 May, 2017

1 commit

  • fe3b81b44   NFS: Use ERR_CAST() to avoid cross-structure cast ... Browse Code »

    When the call to nfs_devname() fails, the error path attempts to retain
    the error via the mnt variable, but this requires a cast across very
    different types (char * to struct vfsmount *), which the upcoming
    structure layout randomization plugin flags as being potentially
    dangerous in the face of randomization. This is a false positive, but
    what this code actually wants to do is retain the error value, so this
    patch explicitly sets it, instead of using what seems to be an
    unexpected cast.

    Signed-off-by: Kees Cook
    Acked-by: Trond Myklebust
    Reviewed-by: Christoph Hellwig

    Kees Cook
     

21 Apr, 2017

1 commit

03 Mar, 2017

1 commit

  • a528d35e8   statx: Add a system call to make enhanced file info available ... Browse Code »

    Add a system call to make extended file information available, including
    file creation and some attribute flags where available through the
    underlying filesystem.

    The getattr inode operation is altered to take two additional arguments: a
    u32 request_mask and an unsigned int flags that indicate the
    synchronisation mode. This change is propagated to the vfs_getattr*()
    function.

    Functions like vfs_stat() are now inline wrappers around new functions
    vfs_statx() and vfs_statx_fd() to reduce stack usage.

    ========
    OVERVIEW
    ========

    The idea was initially proposed as a set of xattrs that could be retrieved
    with getxattr(), but the general preference proved to be for a new syscall
    with an extended stat structure.

    A number of requests were gathered for features to be included. The
    following have been included:

    (1) Make the fields a consistent size on all arches and make them large.

    (2) Spare space, request flags and information flags are provided for
    future expansion.

    (3) Better support for the y2038 problem [Arnd Bergmann] (tv_sec is an
    __s64).

    (4) Creation time: The SMB protocol carries the creation time, which could
    be exported by Samba, which will in turn help CIFS make use of
    FS-Cache as that can be used for coherency data (stx_btime).

    This is also specified in NFSv4 as a recommended attribute and could
    be exported by NFSD [Steve French].

    (5) Lightweight stat: Ask for just those details of interest, and allow a
    netfs (such as NFS) to approximate anything not of interest, possibly
    without going to the server [Trond Myklebust, Ulrich Drepper, Andreas
    Dilger] (AT_STATX_DONT_SYNC).

    (6) Heavyweight stat: Force a netfs to go to the server, even if it thinks
    its cached attributes are up to date [Trond Myklebust]
    (AT_STATX_FORCE_SYNC).

    And the following have been left out for future extension:

    (7) Data version number: Could be used by userspace NFS servers [Aneesh
    Kumar].

    Can also be used to modify fill_post_wcc() in NFSD which retrieves
    i_version directly, but has just called vfs_getattr(). It could get
    it from the kstat struct if it used vfs_xgetattr() instead.

    (There's disagreement on the exact semantics of a single field, since
    not all filesystems do this the same way).

    (8) BSD stat compatibility: Including more fields from the BSD stat such
    as creation time (st_btime) and inode generation number (st_gen)
    [Jeremy Allison, Bernd Schubert].

    (9) Inode generation number: Useful for FUSE and userspace NFS servers
    [Bernd Schubert].

    (This was asked for but later deemed unnecessary with the
    open-by-handle capability available and caused disagreement as to
    whether it's a security hole or not).

    (10) Extra coherency data may be useful in making backups [Andreas Dilger].

    (No particular data were offered, but things like last backup
    timestamp, the data version number and the DOS archive bit would come
    into this category).

    (11) Allow the filesystem to indicate what it can/cannot provide: A
    filesystem can now say it doesn't support a standard stat feature if
    that isn't available, so if, for instance, inode numbers or UIDs don't
    exist or are fabricated locally...

    (This requires a separate system call - I have an fsinfo() call idea
    for this).

    (12) Store a 16-byte volume ID in the superblock that can be returned in
    struct xstat [Steve French].

    (Deferred to fsinfo).

    (13) Include granularity fields in the time data to indicate the
    granularity of each of the times (NFSv4 time_delta) [Steve French].

    (Deferred to fsinfo).

    (14) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags.
    Note that the Linux IOC flags are a mess and filesystems such as Ext4
    define flags that aren't in linux/fs.h, so translation in the kernel
    may be a necessity (or, possibly, we provide the filesystem type too).

    (Some attributes are made available in stx_attributes, but the general
    feeling was that the IOC flags were to ext[234]-specific and shouldn't
    be exposed through statx this way).

    (15) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer,
    Michael Kerrisk].

    (Deferred, probably to fsinfo. Finding out if there's an ACL or
    seclabal might require extra filesystem operations).

    (16) Femtosecond-resolution timestamps [Dave Chinner].

    (A __reserved field has been left in the statx_timestamp struct for
    this - if there proves to be a need).

    (17) A set multiple attributes syscall to go with this.

    ===============
    NEW SYSTEM CALL
    ===============

    The new system call is:

    int ret = statx(int dfd,
    const char *filename,
    unsigned int flags,
    unsigned int mask,
    struct statx *buffer);

    The dfd, filename and flags parameters indicate the file to query, in a
    similar way to fstatat(). There is no equivalent of lstat() as that can be
    emulated with statx() by passing AT_SYMLINK_NOFOLLOW in flags. There is
    also no equivalent of fstat() as that can be emulated by passing a NULL
    filename to statx() with the fd of interest in dfd.

    Whether or not statx() synchronises the attributes with the backing store
    can be controlled by OR'ing a value into the flags argument (this typically
    only affects network filesystems):

    (1) AT_STATX_SYNC_AS_STAT tells statx() to behave as stat() does in this
    respect.

    (2) AT_STATX_FORCE_SYNC will require a network filesystem to synchronise
    its attributes with the server - which might require data writeback to
    occur to get the timestamps correct.

    (3) AT_STATX_DONT_SYNC will suppress synchronisation with the server in a
    network filesystem. The resulting values should be considered
    approximate.

    mask is a bitmask indicating the fields in struct statx that are of
    interest to the caller. The user should set this to STATX_BASIC_STATS to
    get the basic set returned by stat(). It should be noted that asking for
    more information may entail extra I/O operations.

    buffer points to the destination for the data. This must be 256 bytes in
    size.

    ======================
    MAIN ATTRIBUTES RECORD
    ======================

    The following structures are defined in which to return the main attribute
    set:

    struct statx_timestamp {
    __s64 tv_sec;
    __s32 tv_nsec;
    __s32 __reserved;
    };

    struct statx {
    __u32 stx_mask;
    __u32 stx_blksize;
    __u64 stx_attributes;
    __u32 stx_nlink;
    __u32 stx_uid;
    __u32 stx_gid;
    __u16 stx_mode;
    __u16 __spare0[1];
    __u64 stx_ino;
    __u64 stx_size;
    __u64 stx_blocks;
    __u64 __spare1[1];
    struct statx_timestamp stx_atime;
    struct statx_timestamp stx_btime;
    struct statx_timestamp stx_ctime;
    struct statx_timestamp stx_mtime;
    __u32 stx_rdev_major;
    __u32 stx_rdev_minor;
    __u32 stx_dev_major;
    __u32 stx_dev_minor;
    __u64 __spare2[14];
    };

    The defined bits in request_mask and stx_mask are:

    STATX_TYPE Want/got stx_mode & S_IFMT
    STATX_MODE Want/got stx_mode & ~S_IFMT
    STATX_NLINK Want/got stx_nlink
    STATX_UID Want/got stx_uid
    STATX_GID Want/got stx_gid
    STATX_ATIME Want/got stx_atime{,_ns}
    STATX_MTIME Want/got stx_mtime{,_ns}
    STATX_CTIME Want/got stx_ctime{,_ns}
    STATX_INO Want/got stx_ino
    STATX_SIZE Want/got stx_size
    STATX_BLOCKS Want/got stx_blocks
    STATX_BASIC_STATS [The stuff in the normal stat struct]
    STATX_BTIME Want/got stx_btime{,_ns}
    STATX_ALL [All currently available stuff]

    stx_btime is the file creation time, stx_mask is a bitmask indicating the
    data provided and __spares*[] are where as-yet undefined fields can be
    placed.

    Time fields are structures with separate seconds and nanoseconds fields
    plus a reserved field in case we want to add even finer resolution. Note
    that times will be negative if before 1970; in such a case, the nanosecond
    fields will also be negative if not zero.

    The bits defined in the stx_attributes field convey information about a
    file, how it is accessed, where it is and what it does. The following
    attributes map to FS_*_FL flags and are the same numerical value:

    STATX_ATTR_COMPRESSED File is compressed by the fs
    STATX_ATTR_IMMUTABLE File is marked immutable
    STATX_ATTR_APPEND File is append-only
    STATX_ATTR_NODUMP File is not to be dumped
    STATX_ATTR_ENCRYPTED File requires key to decrypt in fs

    Within the kernel, the supported flags are listed by:

    KSTAT_ATTR_FS_IOC_FLAGS

    [Are any other IOC flags of sufficient general interest to be exposed
    through this interface?]

    New flags include:

    STATX_ATTR_AUTOMOUNT Object is an automount trigger

    These are for the use of GUI tools that might want to mark files specially,
    depending on what they are.

    Fields in struct statx come in a number of classes:

    (0) stx_dev_*, stx_blksize.

    These are local system information and are always available.

    (1) stx_mode, stx_nlinks, stx_uid, stx_gid, stx_[amc]time, stx_ino,
    stx_size, stx_blocks.

    These will be returned whether the caller asks for them or not. The
    corresponding bits in stx_mask will be set to indicate whether they
    actually have valid values.

    If the caller didn't ask for them, then they may be approximated. For
    example, NFS won't waste any time updating them from the server,
    unless as a byproduct of updating something requested.

    If the values don't actually exist for the underlying object (such as
    UID or GID on a DOS file), then the bit won't be set in the stx_mask,
    even if the caller asked for the value. In such a case, the returned
    value will be a fabrication.

    Note that there are instances where the type might not be valid, for
    instance Windows reparse points.

    (2) stx_rdev_*.

    This will be set only if stx_mode indicates we're looking at a
    blockdev or a chardev, otherwise will be 0.

    (3) stx_btime.

    Similar to (1), except this will be set to 0 if it doesn't exist.

    =======
    TESTING
    =======

    The following test program can be used to test the statx system call:

    samples/statx/test-statx.c

    Just compile and run, passing it paths to the files you want to examine.
    The file is built automatically if CONFIG_SAMPLES is enabled.

    Here's some example output. Firstly, an NFS directory that crosses to
    another FSID. Note that the AUTOMOUNT attribute is set because transiting
    this directory will cause d_automount to be invoked by the VFS.

    [root@andromeda ~]# /tmp/test-statx -A /warthog/data
    statx(/warthog/data) = 0
    results=7ff
    Size: 4096 Blocks: 8 IO Block: 1048576 directory
    Device: 00:26 Inode: 1703937 Links: 125
    Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041
    Access: 2016-11-24 09:02:12.219699527+0000
    Modify: 2016-11-17 10:44:36.225653653+0000
    Change: 2016-11-17 10:44:36.225653653+0000
    Attributes: 0000000000001000 (-------- -------- -------- -------- -------- -------- ---m---- --------)

    Secondly, the result of automounting on that directory.

    [root@andromeda ~]# /tmp/test-statx /warthog/data
    statx(/warthog/data) = 0
    results=7ff
    Size: 4096 Blocks: 8 IO Block: 1048576 directory
    Device: 00:27 Inode: 2 Links: 125
    Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041
    Access: 2016-11-24 09:02:12.219699527+0000
    Modify: 2016-11-17 10:44:36.225653653+0000
    Change: 2016-11-17 10:44:36.225653653+0000

    Signed-off-by: David Howells
    Signed-off-by: Al Viro

    David Howells
     

01 Feb, 2017

1 commit

  • 93faccbbf   fs: Better permission checking for submounts ... Browse Code »

    To support unprivileged users mounting filesystems two permission
    checks have to be performed: a test to see if the user allowed to
    create a mount in the mount namespace, and a test to see if
    the user is allowed to access the specified filesystem.

    The automount case is special in that mounting the original filesystem
    grants permission to mount the sub-filesystems, to any user who
    happens to stumble across the their mountpoint and satisfies the
    ordinary filesystem permission checks.

    Attempting to handle the automount case by using override_creds
    almost works. It preserves the idea that permission to mount
    the original filesystem is permission to mount the sub-filesystem.
    Unfortunately using override_creds messes up the filesystems
    ordinary permission checks.

    Solve this by being explicit that a mount is a submount by introducing
    vfs_submount, and using it where appropriate.

    vfs_submount uses a new mount internal mount flags MS_SUBMOUNT, to let
    sget and friends know that a mount is a submount so they can take appropriate
    action.

    sget and sget_userns are modified to not perform any permission checks
    on submounts.

    follow_automount is modified to stop using override_creds as that
    has proven problemantic.

    do_mount is modified to always remove the new MS_SUBMOUNT flag so
    that we know userspace will never by able to specify it.

    autofs4 is modified to stop using current_real_cred that was put in
    there to handle the previous version of submount permission checking.

    cifs is modified to pass the mountpoint all of the way down to vfs_submount.

    debugfs is modified to pass the mountpoint all of the way down to
    trace_automount by adding a new parameter. To make this change easier
    a new typedef debugfs_automount_t is introduced to capture the type of
    the debugfs automount function.

    Cc: stable@vger.kernel.org
    Fixes: 069d5ac9ae0d ("autofs: Fix automounts by using current_real_cred()->uid")
    Fixes: aeaa4a79ff6a ("fs: Call d_automount with the filesystems creds")
    Reviewed-by: Trond Myklebust
    Reviewed-by: Seth Forshee
    Signed-off-by: "Eric W. Biederman"

    Eric W. Biederman
     

25 Oct, 2016

1 commit

  • 86a6c211d   NFS: Trim extra slash in v4 nfs_path ... Browse Code »

    A NFSv4 mount of a subdirectory will show an extra slash (as in
    'server://path') in proc's mountinfo which will not match the device name
    and path. This can cause problems for programs searching for the mount.
    Fix this by checking for a leading slash in the dentry path, if so trim
    away any trailing slashes in the device name.

    Signed-off-by: Benjamin Coddington
    Signed-off-by: Anna Schumaker

    Benjamin Coddington
     

16 Apr, 2015

1 commit

25 Oct, 2013

1 commit

09 Jun, 2013

1 commit

  • 1775fd3e8   NFS:Add labels to client function prototypes ... Browse Code »

    After looking at all of the nfsv4 operations the label structure has been added
    to the prototypes of the functions which can transmit label data.

    Signed-off-by: Matthew N. Dodd
    Signed-off-by: Miguel Rodel Felipe
    Signed-off-by: Phua Eu Gene
    Signed-off-by: Khin Mi Mi Aung
    Signed-off-by: Steve Dickson
    Signed-off-by: Trond Myklebust

    David Quigley
     

31 Jan, 2013

1 commit

  • ab2254178   NFS: Don't silently fail setattr() requests on mountpoints ... Browse Code »

    Ensure that any setattr and getattr requests for junctions and/or
    mountpoints are sent to the server. Ever since commit
    0ec26fd0698 (vfs: automount should ignore LOOKUP_FOLLOW), we have
    silently dropped any setattr requests to a server-side mountpoint.
    For referrals, we have silently dropped both getattr and setattr
    requests.

    This patch restores the original behaviour for setattr on mountpoints,
    and tries to do the same for referrals, provided that we have a
    filehandle...

    Signed-off-by: Trond Myklebust
    Cc: stable@vger.kernel.org

    Trond Myklebust
     

01 Nov, 2012

1 commit

  • 97a548682   nfs: Show original device name verbatim in /proc/*/mount{s,info} ... Browse Code »

    Since commit c7f404b ('vfs: new superblock methods to override
    /proc/*/mount{s,info}'), nfs_path() is used to generate the mounted
    device name reported back to userland.

    nfs_path() always generates a trailing slash when the given dentry is
    the root of an NFS mount, but userland may expect the original device
    name to be returned verbatim (as it used to be). Make this
    canonicalisation optional and change the callers accordingly.

    [jrnieder@gmail.com: use flag instead of bool argument]
    Reported-and-tested-by: Chris Hiestand
    Reference: http://bugs.debian.org/669314
    Signed-off-by: Ben Hutchings
    Cc: # v2.6.39+
    Signed-off-by: Jonathan Nieder
    Signed-off-by: Trond Myklebust

    Ben Hutchings
     

31 Jul, 2012

3 commits

  • 89d77c8fa   NFS: Convert v4 into a module ... Browse Code »

    This patch exports symbols needed by the v4 module. In addition, I also
    switch over to using IS_ENABLED() to check if CONFIG_NFS_V4 or
    CONFIG_NFS_V4_MODULE are set.

    The module (nfs4.ko) will be created in the same directory as nfs.ko and
    will be automatically loaded the first time you try to mount over NFS v4.

    Signed-off-by: Bryan Schumaker
    Signed-off-by: Trond Myklebust

    Bryan Schumaker
     
  • ddda8e0aa   NFS: Convert v2 into a module ... Browse Code »

    The module (nfs2.ko) will be created in the same directory as nfs.ko and
    will be automatically loaded the first time you try to mount over NFS v2.

    Signed-off-by: Bryan Schumaker
    Signed-off-by: Trond Myklebust

    Bryan Schumaker
     
  • e8f25e6d6   NFS: Remove the NFS v4 xdev mount function ... Browse Code »

    I can now share this code with the v2 and v3 code by using the NFS
    subversion structure.

    Signed-off-by: Bryan Schumaker
    Signed-off-by: Trond Myklebust

    Bryan Schumaker
     

28 Apr, 2012

6 commits

17 Feb, 2012

1 commit

13 Jul, 2011

1 commit

  • fca78d6d2   NFS: Add SECINFO_NO_NAME procedure ... Browse Code »

    If the client is using NFS v4.1, then we can use SECINFO_NO_NAME to find
    the secflavor for the initial mount. If the server doesn't support
    SECINFO_NO_NAME then I fall back on the "guess and check" method used
    for v4.0 mounts.

    Signed-off-by: Bryan Schumaker
    Signed-off-by: Trond Myklebust

    Bryan Schumaker
     

13 Apr, 2011

1 commit

07 Apr, 2011

1 commit

  • 418875900   NFS: Fix a signed vs. unsigned secinfo bug ... Browse Code »

    rpc_authflavor_t is cast from an unsigned int, but the
    initial code tried to use it as a signed int. I fix
    this by passing an rpc_authflavor_t pointer around, and
    returning signed integers from functions.

    Signed-off-by: Bryan Schumaker
    Reported-by: Dan Carpenter
    Signed-off-by: Trond Myklebust

    Bryan Schumaker
     

27 Mar, 2011

1 commit

25 Mar, 2011

2 commits

21 Mar, 2011

1 commit

17 Mar, 2011

2 commits

16 Jan, 2011

3 commits

  • ea5b778a8   Unexport do_add_mount() and add in follow_automount(), not ->d_automount() ... Browse Code »

    Unexport do_add_mount() and make ->d_automount() return the vfsmount to be
    added rather than calling do_add_mount() itself. follow_automount() will then
    do the addition.

    This slightly complicates things as ->d_automount() normally wants to add the
    new vfsmount to an expiration list and start an expiration timer. The problem
    with that is that the vfsmount will be deleted if it has a refcount of 1 and
    the timer will not repeat if the expiration list is empty.

    To this end, we require the vfsmount to be returned from d_automount() with a
    refcount of (at least) 2. One of these refs will be dropped unconditionally.
    In addition, follow_automount() must get a 3rd ref around the call to
    do_add_mount() lest it eat a ref and return an error, leaving the mount we
    have open to being expired as we would otherwise have only 1 ref on it.

    d_automount() should also add the the vfsmount to the expiration list (by
    calling mnt_set_expiry()) and start the expiration timer before returning, if
    this mechanism is to be used. The vfsmount will be unlinked from the
    expiration list by follow_automount() if do_add_mount() fails.

    This patch also fixes the call to do_add_mount() for AFS to propagate the mount
    flags from the parent vfsmount.

    Signed-off-by: David Howells
    Signed-off-by: Al Viro

    David Howells
     
  • 36d43a437   NFS: Use d_automount() rather than abusing follow_link() ... Browse Code »
    43

    Make NFS use the new d_automount() dentry operation rather than abusing
    follow_link() on directories.

    Signed-off-by: David Howells
    Acked-by: Trond Myklebust
    Acked-by: Ian Kent
    Signed-off-by: Al Viro

    David Howells
     
  • cc53ce53c   Add a dentry op to allow processes to be held during pathwalk transit ... Browse Code »

    Add a dentry op (d_manage) to permit a filesystem to hold a process and make it
    sleep when it tries to transit away from one of that filesystem's directories
    during a pathwalk. The operation is keyed off a new dentry flag
    (DCACHE_MANAGE_TRANSIT).

    The filesystem is allowed to be selective about which processes it holds and
    which it permits to continue on or prohibits from transiting from each flagged
    directory. This will allow autofs to hold up client processes whilst letting
    its userspace daemon through to maintain the directory or the stuff behind it
    or mounted upon it.

    The ->d_manage() dentry operation:

    int (*d_manage)(struct path *path, bool mounting_here);

    takes a pointer to the directory about to be transited away from and a flag
    indicating whether the transit is undertaken by do_add_mount() or
    do_move_mount() skipping through a pile of filesystems mounted on a mountpoint.

    It should return 0 if successful and to let the process continue on its way;
    -EISDIR to prohibit the caller from skipping to overmounted filesystems or
    automounting, and to use this directory; or some other error code to return to
    the user.

    ->d_manage() is called with namespace_sem writelocked if mounting_here is true
    and no other locks held, so it may sleep. However, if mounting_here is true,
    it may not initiate or wait for a mount or unmount upon the parameter
    directory, even if the act is actually performed by userspace.

    Within fs/namei.c, follow_managed() is extended to check with d_manage() first
    on each managed directory, before transiting away from it or attempting to
    automount upon it.

    follow_down() is renamed follow_down_one() and should only be used where the
    filesystem deliberately intends to avoid management steps (e.g. autofs).

    A new follow_down() is added that incorporates the loop done by all other
    callers of follow_down() (do_add/move_mount(), autofs and NFSD; whilst AFS, NFS
    and CIFS do use it, their use is removed by converting them to use
    d_automount()). The new follow_down() calls d_manage() as appropriate. It
    also takes an extra parameter to indicate if it is being called from mount code
    (with namespace_sem writelocked) which it passes to d_manage(). follow_down()
    ignores automount points so that it can be used to mount on them.

    __follow_mount_rcu() is made to abort rcu-walk mode if it hits a directory with
    DCACHE_MANAGE_TRANSIT set on the basis that we're probably going to have to
    sleep. It would be possible to enter d_manage() in rcu-walk mode too, and have
    that determine whether to abort or not itself. That would allow the autofs
    daemon to continue on in rcu-walk mode.

    Note that DCACHE_MANAGE_TRANSIT on a directory should be cleared when it isn't
    required as every tranist from that directory will cause d_manage() to be
    invoked. It can always be set again when necessary.

    ==========================
    WHAT THIS MEANS FOR AUTOFS
    ==========================

    Autofs currently uses the lookup() inode op and the d_revalidate() dentry op to
    trigger the automounting of indirect mounts, and both of these can be called
    with i_mutex held.

    autofs knows that the i_mutex will be held by the caller in lookup(), and so
    can drop it before invoking the daemon - but this isn't so for d_revalidate(),
    since the lock is only held on _some_ of the code paths that call it. This
    means that autofs can't risk dropping i_mutex from its d_revalidate() function
    before it calls the daemon.

    The bug could manifest itself as, for example, a process that's trying to
    validate an automount dentry that gets made to wait because that dentry is
    expired and needs cleaning up:

    mkdir S ffffffff8014e05a 0 32580 24956
    Call Trace:
    [] :autofs4:autofs4_wait+0x674/0x897
    [] avc_has_perm+0x46/0x58
    [] autoremove_wake_function+0x0/0x2e
    [] :autofs4:autofs4_expire_wait+0x41/0x6b
    [] :autofs4:autofs4_revalidate+0x91/0x149
    [] __lookup_hash+0xa0/0x12f
    [] lookup_create+0x46/0x80
    [] sys_mkdirat+0x56/0xe4

    versus the automount daemon which wants to remove that dentry, but can't
    because the normal process is holding the i_mutex lock:

    automount D ffffffff8014e05a 0 32581 1 32561
    Call Trace:
    [] __mutex_lock_slowpath+0x60/0x9b
    [] do_path_lookup+0x2ca/0x2f1
    [] .text.lock.mutex+0xf/0x14
    [] do_rmdir+0x77/0xde
    [] tracesys+0x71/0xe0
    [] tracesys+0xd5/0xe0

    which means that the system is deadlocked.

    This patch allows autofs to hold up normal processes whilst the daemon goes
    ahead and does things to the dentry tree behind the automouter point without
    risking a deadlock as almost no locks are held in d_manage() and none in
    d_automount().

    Signed-off-by: David Howells
    Was-Acked-by: Ian Kent
    Signed-off-by: Al Viro

    David Howells
     

07 Jan, 2011

2 commits

  • b5c84bf6f   fs: dcache remove dcache_lock ... Browse Code »

    dcache_lock no longer protects anything. remove it.

    Signed-off-by: Nick Piggin

    Nick Piggin
     
  • 949854d02   fs: Use rename lock and RCU for multi-step operations ... Browse Code »

    The remaining usages for dcache_lock is to allow atomic, multi-step read-side
    operations over the directory tree by excluding modifications to the tree.
    Also, to walk in the leaf->root direction in the tree where we don't have
    a natural d_lock ordering.

    This could be accomplished by taking every d_lock, but this would mean a
    huge number of locks and actually gets very tricky.

    Solve this instead by using the rename seqlock for multi-step read-side
    operations, retry in case of a rename so we don't walk up the wrong parent.
    Concurrent dentry insertions are not serialised against. Concurrent deletes
    are tricky when walking up the directory: our parent might have been deleted
    when dropping locks so also need to check and retry for that.

    We can also use the rename lock in cases where livelock is a worry (and it
    is introduced in subsequent patch).

    Signed-off-by: Nick Piggin

    Nick Piggin
     

15 May, 2010

1 commit

30 Mar, 2010

1 commit

  • 5a0e3ad6a   include cleanup: Update gfp.h and slab.h includes to prepare for breaking implic… ... Browse Code »

    …it slab.h inclusion from percpu.h

    percpu.h is included by sched.h and module.h and thus ends up being
    included when building most .c files. percpu.h includes slab.h which
    in turn includes gfp.h making everything defined by the two files
    universally available and complicating inclusion dependencies.

    percpu.h -> slab.h dependency is about to be removed. Prepare for
    this change by updating users of gfp and slab facilities include those
    headers directly instead of assuming availability. As this conversion
    needs to touch large number of source files, the following script is
    used as the basis of conversion.

    http://userweb.kernel.org/~tj/misc/slabh-sweep.py

    The script does the followings.

    * Scan files for gfp and slab usages and update includes such that
    only the necessary includes are there. ie. if only gfp is used,
    gfp.h, if slab is used, slab.h.

    * When the script inserts a new include, it looks at the include
    blocks and try to put the new include such that its order conforms
    to its surrounding. It's put in the include block which contains
    core kernel includes, in the same order that the rest are ordered -
    alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
    doesn't seem to be any matching order.

    * If the script can't find a place to put a new include (mostly
    because the file doesn't have fitting include block), it prints out
    an error message indicating which .h file needs to be added to the
    file.

    The conversion was done in the following steps.

    1. The initial automatic conversion of all .c files updated slightly
    over 4000 files, deleting around 700 includes and adding ~480 gfp.h
    and ~3000 slab.h inclusions. The script emitted errors for ~400
    files.

    2. Each error was manually checked. Some didn't need the inclusion,
    some needed manual addition while adding it to implementation .h or
    embedding .c file was more appropriate for others. This step added
    inclusions to around 150 files.

    3. The script was run again and the output was compared to the edits
    from #2 to make sure no file was left behind.

    4. Several build tests were done and a couple of problems were fixed.
    e.g. lib/decompress_*.c used malloc/free() wrappers around slab
    APIs requiring slab.h to be added manually.

    5. The script was run on all .h files but without automatically
    editing them as sprinkling gfp.h and slab.h inclusions around .h
    files could easily lead to inclusion dependency hell. Most gfp.h
    inclusion directives were ignored as stuff from gfp.h was usually
    wildly available and often used in preprocessor macros. Each
    slab.h inclusion directive was examined and added manually as
    necessary.

    6. percpu.h was updated not to include slab.h.

    7. Build test were done on the following configurations and failures
    were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
    distributed build env didn't work with gcov compiles) and a few
    more options had to be turned off depending on archs to make things
    build (like ipr on powerpc/64 which failed due to missing writeq).

    * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
    * powerpc and powerpc64 SMP allmodconfig
    * sparc and sparc64 SMP allmodconfig
    * ia64 SMP allmodconfig
    * s390 SMP allmodconfig
    * alpha SMP allmodconfig
    * um on x86_64 SMP allmodconfig

    8. percpu.h modifications were reverted so that it could be applied as
    a separate patch and serve as bisection point.

    Given the fact that I had only a couple of failures from tests on step
    6, I'm fairly confident about the coverage of this conversion patch.
    If there is a breakage, it's likely to be something in one of the arch
    headers which should be easily discoverable easily on most builds of
    the specific arch.

    Signed-off-by: Tejun Heo <tj@kernel.org>
    Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

    Tejun Heo
     

23 Jun, 2009

1 commit

12 Jun, 2009

1 commit