3bc303c254
This is the fourth respin of the patch to convert oplock breaks to use the slow_work facility. A customer of ours was testing a backport of one of the earlier patchsets, and hit a "Busy inodes after umount..." problem. An oplock break job had raced with a umount, and the superblock got torn down and its memory reused. When the oplock break job tried to dereference the inode->i_sb, the kernel oopsed. This patchset has the oplock break job hold an inode and vfsmount reference until the oplock break completes. With this, there should be no need to take a tcon reference (the vfsmount implicitly holds one already). Currently, when an oplock break comes in there's a chance that the oplock break job won't occur if the allocation of the oplock_q_entry fails. There are also some rather nasty races in the allocation and handling these structs. Rather than allocating oplock queue entries when an oplock break comes in, add a few extra fields to the cifsFileInfo struct. Get rid of the dedicated cifs_oplock_thread as well and queue the oplock break job to the slow_work thread pool. This approach also has the advantage that the oplock break jobs can potentially run in parallel rather than be serialized like they are today. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <sfrench@us.ibm.com>
146 lines
6.2 KiB
Text
146 lines
6.2 KiB
Text
config CIFS
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tristate "CIFS support (advanced network filesystem, SMBFS successor)"
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depends on INET
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select NLS
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select SLOW_WORK
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help
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This is the client VFS module for the Common Internet File System
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(CIFS) protocol which is the successor to the Server Message Block
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(SMB) protocol, the native file sharing mechanism for most early
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PC operating systems. The CIFS protocol is fully supported by
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file servers such as Windows 2000 (including Windows 2003, NT 4
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and Windows XP) as well by Samba (which provides excellent CIFS
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server support for Linux and many other operating systems). Limited
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support for OS/2 and Windows ME and similar servers is provided as
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well.
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The cifs module provides an advanced network file system
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client for mounting to CIFS compliant servers. It includes
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support for DFS (hierarchical name space), secure per-user
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session establishment via Kerberos or NTLM or NTLMv2,
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safe distributed caching (oplock), optional packet
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signing, Unicode and other internationalization improvements.
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If you need to mount to Samba or Windows from this machine, say Y.
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config CIFS_STATS
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bool "CIFS statistics"
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depends on CIFS
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help
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Enabling this option will cause statistics for each server share
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mounted by the cifs client to be displayed in /proc/fs/cifs/Stats
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config CIFS_STATS2
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bool "Extended statistics"
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depends on CIFS_STATS
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help
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Enabling this option will allow more detailed statistics on SMB
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request timing to be displayed in /proc/fs/cifs/DebugData and also
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allow optional logging of slow responses to dmesg (depending on the
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value of /proc/fs/cifs/cifsFYI, see fs/cifs/README for more details).
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These additional statistics may have a minor effect on performance
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and memory utilization.
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Unless you are a developer or are doing network performance analysis
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or tuning, say N.
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config CIFS_WEAK_PW_HASH
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bool "Support legacy servers which use weaker LANMAN security"
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depends on CIFS
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help
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Modern CIFS servers including Samba and most Windows versions
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(since 1997) support stronger NTLM (and even NTLMv2 and Kerberos)
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security mechanisms. These hash the password more securely
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than the mechanisms used in the older LANMAN version of the
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SMB protocol but LANMAN based authentication is needed to
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establish sessions with some old SMB servers.
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Enabling this option allows the cifs module to mount to older
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LANMAN based servers such as OS/2 and Windows 95, but such
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mounts may be less secure than mounts using NTLM or more recent
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security mechanisms if you are on a public network. Unless you
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have a need to access old SMB servers (and are on a private
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network) you probably want to say N. Even if this support
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is enabled in the kernel build, LANMAN authentication will not be
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used automatically. At runtime LANMAN mounts are disabled but
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can be set to required (or optional) either in
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/proc/fs/cifs (see fs/cifs/README for more detail) or via an
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option on the mount command. This support is disabled by
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default in order to reduce the possibility of a downgrade
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attack.
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If unsure, say N.
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config CIFS_UPCALL
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bool "Kerberos/SPNEGO advanced session setup"
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depends on CIFS && KEYS
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help
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Enables an upcall mechanism for CIFS which accesses
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userspace helper utilities to provide SPNEGO packaged (RFC 4178)
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Kerberos tickets which are needed to mount to certain secure servers
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(for which more secure Kerberos authentication is required). If
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unsure, say N.
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config CIFS_XATTR
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bool "CIFS extended attributes"
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depends on CIFS
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help
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Extended attributes are name:value pairs associated with inodes by
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the kernel or by users (see the attr(5) manual page, or visit
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<http://acl.bestbits.at/> for details). CIFS maps the name of
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extended attributes beginning with the user namespace prefix
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to SMB/CIFS EAs. EAs are stored on Windows servers without the
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user namespace prefix, but their names are seen by Linux cifs clients
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prefaced by the user namespace prefix. The system namespace
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(used by some filesystems to store ACLs) is not supported at
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this time.
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If unsure, say N.
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config CIFS_POSIX
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bool "CIFS POSIX Extensions"
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depends on CIFS_XATTR
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help
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Enabling this option will cause the cifs client to attempt to
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negotiate a newer dialect with servers, such as Samba 3.0.5
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or later, that optionally can handle more POSIX like (rather
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than Windows like) file behavior. It also enables
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support for POSIX ACLs (getfacl and setfacl) to servers
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(such as Samba 3.10 and later) which can negotiate
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CIFS POSIX ACL support. If unsure, say N.
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config CIFS_DEBUG2
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bool "Enable additional CIFS debugging routines"
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depends on CIFS
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help
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Enabling this option adds a few more debugging routines
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to the cifs code which slightly increases the size of
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the cifs module and can cause additional logging of debug
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messages in some error paths, slowing performance. This
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option can be turned off unless you are debugging
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cifs problems. If unsure, say N.
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config CIFS_DFS_UPCALL
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bool "DFS feature support"
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depends on CIFS && KEYS
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help
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Distributed File System (DFS) support is used to access shares
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transparently in an enterprise name space, even if the share
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moves to a different server. This feature also enables
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an upcall mechanism for CIFS which contacts userspace helper
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utilities to provide server name resolution (host names to
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IP addresses) which is needed for implicit mounts of DFS junction
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points. If unsure, say N.
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config CIFS_EXPERIMENTAL
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bool "CIFS Experimental Features (EXPERIMENTAL)"
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depends on CIFS && EXPERIMENTAL
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help
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Enables cifs features under testing. These features are
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experimental and currently include DFS support and directory
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change notification ie fcntl(F_DNOTIFY), as well as the upcall
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mechanism which will be used for Kerberos session negotiation
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and uid remapping. Some of these features also may depend on
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setting a value of 1 to the pseudo-file /proc/fs/cifs/Experimental
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(which is disabled by default). See the file fs/cifs/README
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for more details. If unsure, say N.
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