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2005-09-23SUNRPC: fix bug in patch "portmapper doesn't need a reserved port"Chuck Lever
The in-kernel portmapper does in fact need a reserved port when registering new services, but not when performing bind queries. Ensure that we distinguish between the two cases. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23Revert "[PATCH] RPC,NFS: new rpc_pipefs patch"Trond Myklebust
This reverts 17f4e6febca160a9f9dd4bdece9784577a2f4524 commit.
2005-09-23NFS: Make /proc/mounts display the protocol used by NFSv4Trond Myklebust
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC,NFS: new rpc_pipefs patchChristoph Hellwig
Currently rpc_mkdir/rpc_rmdir and rpc_mkpipe/mk_unlink have an API that's a little unfortunate. They take a path relative to the rpc_pipefs root and thus need to perform a full lookup. If you look at debugfs or usbfs they always store the dentry for directories they created and thus can pass in a dentry + single pathname component pair into their equivalents of the above functions. And in fact rpc_pipefs actually stores a dentry for all but one component so this change not only simplifies the core rpc_pipe code but also the callers. Unfortuntately this code path is only used by the NFS4 idmapper and AUTH_GSSAPI for which I don't have a test enviroment. Could someone give it a spin? It's the last bit needed before we can rework the lookup_hash API Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: rationalize set_buffer_sizeChuck Lever
In fact, ->set_buffer_size should be completely functionless for non-UDP. Test-plan: Check socket buffer size on UDP sockets over time. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: parametrize various transport connect timeoutsChuck Lever
Each transport implementation can now set unique bind, connect, reestablishment, and idle timeout values. These are variables, allowing the values to be modified dynamically. This permits exponential backoff of any of these values, for instance. As an example, we implement exponential backoff for the connection reestablishment timeout. Test-plan: Destructive testing (unplugging the network temporarily). Connectathon with UDP and TCP. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: make sure to get the same local port number when reconnectingChuck Lever
Implement a best practice: if the remote end drops our connection, try to reconnect using the same port number. This is important because the NFS server's Duplicate Reply Cache often hashes on the source port number. If the client reuses the port number when it reconnects, the server's DRC will be more effective. Based on suggestions by Mike Eisler, Olaf Kirch, and Alexey Kuznetsky. Test-plan: Destructive testing. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: allow RPC client's port range to be adjustableChuck Lever
Select an RPC client source port between 650 and 1023 instead of between 1 and 800. The old range conflicts with a number of network services. Provide sysctls to allow admins to select a different port range. Note that this doesn't affect user-level RPC library behavior, which still uses 1 to 800. Based on a suggestion by Olaf Kirch <okir@suse.de>. Test-plan: Repeated mount and unmount. Destructive testing. Idle timeouts. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: clean up after nocong was removedChuck Lever
Clean-up: Move some macros that are specific to the Van Jacobson implementation into xprt.c. Get rid of the cong_wait field in rpc_xprt, which is no longer used. Get rid of xprt_clear_backlog. Test-plan: Compile with CONFIG_NFS enabled. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: remove xprt->nocongChuck Lever
Get rid of the "xprt->nocong" variable. Test-plan: Use WAN simulation to cause sporadic bursty packet loss with UDP mounts. Look for significant regression in performance or client stability. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: add a release_rqst callout to the RPC transport switchChuck Lever
The final place where congestion control state is adjusted is in xprt_release, where each request is finally released. Add a callout there to allow transports to perform additional processing when a request is about to be released. Test-plan: Use WAN simulation to cause sporadic bursty packet loss. Look for significant regression in performance or client stability. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: add generic interface for adjusting the congestion windowChuck Lever
A new interface that allows transports to adjust their congestion window using the Van Jacobson implementation in xprt.c is provided. Test-plan: Use WAN simulation to cause sporadic bursty packet loss. Look for significant regression in performance or client stability. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: separate xprt_timer implementationsChuck Lever
Allow transports to hook the retransmit timer interrupt. Some transports calculate their congestion window here so that a retransmit timeout has immediate effect on the congestion window. Test-plan: Use WAN simulation to cause sporadic bursty packet loss. Look for significant regression in performance or client stability. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: expose API for serializing access to RPC transportsChuck Lever
The next method we abstract is the one that releases a transport, allowing another task to have access to the transport. Again, one generic version of this is provided for transports that don't need the RPC client to perform congestion control, and one version is for transports that can use the original Van Jacobson implementation in xprt.c. Test-plan: Use WAN simulation to cause sporadic bursty packet loss. Look for significant regression in performance or client stability. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: expose API for serializing access to RPC transportsChuck Lever
The next several patches introduce an API that allows transports to choose whether the RPC client provides congestion control or whether the transport itself provides it. The first method we abstract is the one that serializes access to the RPC transport to prevent the bytes from different requests from mingling together. This method provides proper request serialization and the opportunity to prevent new requests from being started because the transport is congested. The normal situation is for the transport to handle congestion control itself. Although NFS over UDP was first, it has been recognized after years of experience that having the transport provide congestion control is much better than doing it in the RPC client. Thus TCP, and probably every future transport implementation, will use the default method, xprt_lock_write, provided in xprt.c, which does not provide any kind of congestion control. UDP can continue using the xprt.c-provided Van Jacobson congestion avoidance implementation. Test-plan: Use WAN simulation to cause sporadic bursty packet loss. Look for significant regression in performance or client stability. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: add API to set transport-specific timeoutsChuck Lever
Prepare the way to remove the "xprt->nocong" variable by adding a callout to the RPC client transport switch API to handle setting RPC retransmit timeouts. Add a pair of generic helper functions that provide the ability to set a simple fixed timeout, or to set a timeout based on the state of a round- trip estimator. Test-plan: Use WAN simulation to cause sporadic bursty packet loss. Look for significant regression in performance or client stability. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: get rid of xprt->streamChuck Lever
Now we can fix up the last few places that use the "xprt->stream" variable, and get rid of it from the rpc_xprt structure. Test-plan: Destructive testing (unplugging the network temporarily). Connectathon with UDP and TCP. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: skip over transport-specific heads automaticallyChuck Lever
Add a generic mechanism for skipping over transport-specific headers when constructing an RPC request. This removes another "xprt->stream" dependency. Test-plan: Write-intensive workload on a single mount point (try both UDP and TCP). Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: separate TCP and UDP socket write pathsChuck Lever
Split the RPC client's main socket write path into a TCP version and a UDP version to eliminate another dependency on the "xprt->stream" variable. Compiler optimization removes unneeded code from xs_sendpages, as this function is now called with some constant arguments. We can now cleanly perform transport protocol-specific return code testing and error recovery in each path. Test-plan: Millions of fsx operations. Performance characterization such as "sio" or "iozone". Examine oprofile results for any changes before and after this patch is applied. Version: Thu, 11 Aug 2005 16:08:46 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: separate TCP and UDP transport connection logicChuck Lever
Create separate connection worker functions for managing UDP and TCP transport sockets. This eliminates several dependencies on "xprt->stream". Test-plan: Destructive testing (unplugging the network temporarily). Connectathon with v2, v3, and v4. Version: Thu, 11 Aug 2005 16:08:18 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: separate TCP and UDP write space callbacksChuck Lever
Split the socket write space callback function into a TCP version and UDP version, eliminating one dependence on the "xprt->stream" variable. Keep the common pieces of this path in xprt.c so other transports can use it too. Test-plan: Write-intensive workload on a single mount point. Version: Thu, 11 Aug 2005 16:07:51 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: client-side transport switch cleanupChuck Lever
Clean-up: change some comments to reflect the realities of the new RPC transport switch mechanism. Get rid of unused xprt_receive() prototype. Also, organize function prototypes in xprt.h by usage and scope. Test-plan: Compile kernel with CONFIG_NFS enabled. Version: Thu, 11 Aug 2005 16:07:21 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: Add helper for waking tasks pending on a transportChuck Lever
Clean-up: remove only reference to xprt->pending from the socket transport implementation. This makes a cleaner interface for other transport implementations as well. Test-plan: Compile kernel with CONFIG_NFS enabled. Version: Thu, 11 Aug 2005 16:06:52 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: Eliminate socket.h includes in RPC clientChuck Lever
Clean-up: get rid of unnecessary socket.h and in.h includes in the generic parts of the RPC client. Test-plan: Compile kernel with CONFIG_NFS enabled. Version: Thu, 11 Aug 2005 16:06:23 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: rename the sockstate fieldChuck Lever
Clean-up: get rid of a name reference to sockets in the generic parts of the RPC client by renaming the sockstate field in the rpc_xprt structure. Test-plan: Compile kernel with CONFIG_NFS enabled. Version: Thu, 11 Aug 2005 16:05:53 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: Rename xprt_lockChuck Lever
Clean-up: Replace the xprt_lock with something more aptly named. This lock single-threads the XID and request slot reservation process. Test-plan: Compile kernel with CONFIG_NFS enabled. Version: Thu, 11 Aug 2005 16:05:26 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: Rename sock_lockChuck Lever
Clean-up: replace a name reference to sockets in the generic parts of the RPC client by renaming sock_lock in the rpc_xprt structure. Test-plan: Compile kernel with CONFIG_NFS enabled. Version: Thu, 11 Aug 2005 16:05:00 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: Reduce stack utilization in xs_sendpagesChuck Lever
Reduce stack utilization of the RPC socket transport's send path. A couple of unlikely()s are added to ensure the compiler places the tail processing at the end of the csect. Test-plan: Millions of fsx operations. Performance characterization such as "sio" or "iozone". Version: Thu, 11 Aug 2005 16:04:30 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: transport switch function namingChuck Lever
Introduce block header comments and a function naming convention to the socket transport implementation. Provide a debug setting for transports that is separate from RPCDBG_XPRT. Eliminate xprt_default_timeout(). Provide block comments for exposed interfaces in xprt.c, and eliminate the useless obvious comments. Convert printk's to dprintk's. Test-plan: Compile kernel with CONFIG_NFS enabled. Version: Thu, 11 Aug 2005 16:04:04 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: introduce client-side transport switchChuck Lever
Move the bulk of client-side socket-specific code into a separate source file, net/sunrpc/xprtsock.c. Test-plan: Millions of fsx operations. Performance characterization such as "sio" or "iozone". Destructive testing (unplugging the network temporarily, server reboots). Connectathon with v2, v3, and v4. Version: Thu, 11 Aug 2005 16:03:38 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: extract socket logic common to both client and serverChuck Lever
Clean-up: Move some code that is common to both RPC client- and server-side socket transports into its own source file, net/sunrpc/socklib.c. Test-plan: Compile kernel with CONFIG_NFS enabled. Millions of fsx operations over UDP, client and server. Connectathon over UDP. Version: Thu, 11 Aug 2005 16:03:09 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: portmapper doesn't need a reserved portChuck Lever
The in-kernel portmapper does not require a reserved port for making bind queries. Test-plan: Tens of runs of the Connectathon locking suite with TCP and UDP against several other NFS server implementations using NFSv3, not NFSv4 (which doesn't require rpcbind). Version: Thu, 11 Aug 2005 16:02:43 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] NFS: use a constant value for TCP retransmit timeoutsChuck Lever
Implement a best practice: don't use exponential backoff when computing retransmit timeout values on TCP connections, but simply retransmit at regular intervals. This also fixes a bug introduced when xprt_reset_majortimeo() was added. Test-plan: Enable RPC debugging and watch timeout behavior on a NFS/TCP mount. Version: Thu, 11 Aug 2005 16:02:19 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: proper soft timeout behavior for rpcbindChuck Lever
Implement a best practice: for soft mounts, an rpcbind timeout should cause an RPC request to fail. This also provides an FSM hook for retrying an rpcbind with a different rpcbind protocol version. We'll use this later to try multiple rpcbind protocol versions when binding. To enable this, expose the RPC error code returned during a portmap request to the FSM so it can make some decision about how to report, retry, or fail the request. Test-plan: Hundreds of passes with connectathon NFSv3 locking suite, on the client and server. Version: Thu, 11 Aug 2005 16:01:53 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] RPC: Report connection errors properly when mounting with "soft"Chuck Lever
Fix up xprt_connect_status: the soft timeout logic was clobbering tk_status, so TCP connect errors were not properly reported on soft mounts. Test-plan: Destructive testing (unplugging the network temporarily). Connectathon with UDP and TCP. Version: Thu, 11 Aug 2005 16:01:28 -0400 Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23NFS: Don't expose internal READDIR errors to userspaceTrond Myklebust
Fixes a condition whereby the kernel is returning the non-POSIX error EBADCOOKIE to userspace. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23From: Olaf Kirch <okir@suse.de>Olaf Kirch
[PATCH] Fix miscompare in __posix_lock_file If an application requests the same lock twice, the kernel should just leave the existing lock in place. Currently, it will install a second lock of the same type. Signed-off-by: Olaf Kirch <okir@suse.de> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23NFS: Drop inode after renameTrond Myklebust
When doing a rename on top of an existing file that is not in use, the inode of the overwritten file will remain in the icache. The fix is to decrement i_nlink of the overwritten inode, like we do for unlink, rmdir etc already. Problem diagnosed by Olaf Kirch. This patch is a slight variation on his fix. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2005-09-23[PATCH] pci: fixup parent subordinate busnrIvan Kokshaysky
I believe the change that broke things is introduction of pci_fixup_parent_subordinate_busnr(). The patch here does two things: - hunk #1 should fix the problems you've seen when you boot without additional "pci" kernel options; - hunk #2 supposedly fixes boot with "pci=assign-busses" option which otherwise hangs Acer TM81xx machines as reported. Please try this with and without "pci=assign-busses". If it boots, I'd like to see 'lspci -vvx' for both cases. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-23Merge branch 'for-linus' of ↵Linus Torvalds
master.kernel.org:/pub/scm/linux/kernel/git/shaggy/jfs-2.6
2005-09-22[SCTP]: Fix SCTP_SHUTDOWN notifications.Sridhar Samudrala
Fix to allow SCTP_SHUTDOWN notifications to be received on 1-1 style SCTP SOCK_STREAM sockets. Add SCTP_SHUTDOWN notification to the receive queue before updating the state of the association. Signed-off-by: Sridhar Samudrala <sri@us.ibm.com> Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-22[NETFILTER] Fix conntrack event cache deadlock/oopsHarald Welte
This patch fixes a number of bugs. It cannot be reasonably split up in multiple fixes, since all bugs interact with each other and affect the same function: Bug #1: The event cache code cannot be called while a lock is held. Therefore, the call to ip_conntrack_event_cache() within ip_ct_refresh_acct() needs to be moved outside of the locked section. This fixes a number of 2.6.14-rcX oops and deadlock reports. Bug #2: We used to call ct_add_counters() for unconfirmed connections without holding a lock. Since the add operations are not atomic, we could race with another CPU. Bug #3: ip_ct_refresh_acct() lost REFRESH events in some cases where refresh (and the corresponding event) are desired, but no accounting shall be performed. Both, evenst and accounting implicitly depended on the skb parameter bein non-null. We now re-introduce a non-accounting "ip_ct_refresh()" variant to explicitly state the desired behaviour. Signed-off-by: Harald Welte <laforge@netfilter.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-22[NETFILTER] remove unneeded structure definition from conntrack helperHarald Welte
Signed-off-by: Harald Welte <laforge@netfilter.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-22[NETFILTER] Fix sparse endian warnings in pptp helperAlexey Dobriyan
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Harald Welte <laforge@netfilter.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-22[NETFILTER] fix DEBUG statement in PPTP helperHarald Welte
As noted by Alexey Dobriyan, the DEBUGP statement prints the wrong callID. Signed-off-by: Harald Welte <laforge@netfilter.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-22[BRIDGE]: TSO fix in br_dev_queue_push_xmitVlad Drukker
Signed-off-by: Vlad Drukker <vlad@storewiz.com> Acked-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-22[TCP]: Adjust Reno SACK estimate in tcp_fragmentHerbert Xu
Since the introduction of TSO pcount a year ago, it has been possible for tcp_fragment() to cause packets_out to decrease. Prior to that, tcp_retrans_try_collapse() was the only way for that to happen on the retransmission path. When this happens with Reno, it is possible for sasked_out to become invalid because it is only an estimate and not tied to any particular packet on the retransmission queue. Therefore we need to adjust sacked_out as well as left_out in the Reno case. The following patch does exactly that. This bug is pretty difficult to trigger in practice though since you need a SACKless peer with a retransmission that occurs just as the cached MTU value expires. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-22[PATCH] Add dm-snapshot tutorial in DocumentationPaolo 'Blaisorblade' Giarrusso
I've recently discovered the real functionality of device-mapper snapshots, and since they are not well known, I've decided to write some docs for them. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-22[PATCH] NFS: fix client oops when debugging is onNick Wilson
nfs_readpage_release() causes an oops while accessing a file with NFS debugging turned on (echo 32767 > /proc/sys/sunrpc/nfs_debug) and a kernel built with CONFIG_DEBUG_SLAB. This patch moves the debugging statement above nfs_release_request() to avoid accessing freed memory. Signed-off-by: Nick Wilson <njw@osdl.org> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-22[PATCH] Fix bd_claim() error code.Rob Landley
Problem: In some circumstances, bd_claim() is returning the wrong error code. If we try to swapon an unused block device that isn't swap formatted, we get -EINVAL. But if that same block device is already mounted, we instead get -EBUSY, even though it still isn't a valid swap device. This issue came up on the busybox list trying to get the error message from "swapon -a" right. If a swap device is already enabled, we get -EBUSY, and we shouldn't report this as an error. But we can't distinguish the two -EBUSY conditions, which are very different errors. In the code, bd_claim() returns either 0 or -EBUSY, but in this case busy means "somebody other than sys_swapon has already claimed this", and _that_ means this block device can't be a valid swap device. So return -EINVAL there. Signed-off-by: Rob Landley <rob@landley.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>