linux-stable.git/fs/afs, branch linux-5.6.y

rxrpc: Fix the excessive initial retransmission timeout

2020-05-27T15:48:28+00:00

commit c410bf01933e5e09d142c66c3df9ad470a7eec13 upstream.

rxrpc currently uses a fixed 4s retransmission timeout until the RTT is
sufficiently sampled. This can cause problems with some fileservers with
calls to the cache manager in the afs filesystem being dropped from the
fileserver because a packet goes missing and the retransmission timeout is
greater than the call expiry timeout.

Fix this by:

(1) Copying the RTT/RTO calculation code from Linux's TCP implementation
and altering it to fit rxrpc.

(2) Altering the various users of the RTT to make use of the new SRTT
value.

(3) Replacing the use of rxrpc_resend_timeout to use the calculated RTO
value instead (which is needed in jiffies), along with a backoff.

Notes:

(1) rxrpc provides RTT samples by matching the serial numbers on outgoing
DATA packets that have the RXRPC_REQUEST_ACK set and PING ACK packets
against the reference serial number in incoming REQUESTED ACK and
PING-RESPONSE ACK packets.

(2) Each packet that is transmitted on an rxrpc connection gets a new
per-connection serial number, even for retransmissions, so an ACK can
be cross-referenced to a specific trigger packet. This allows RTT
information to be drawn from retransmitted DATA packets also.

(3) rxrpc maintains the RTT/RTO state on the rxrpc_peer record rather than
on an rxrpc_call because many RPC calls won't live long enough to
generate more than one sample.

(4) The calculated SRTT value is in units of 8ths of a microsecond rather
than nanoseconds.

The (S)RTT and RTO values are displayed in /proc/net/rxrpc/peers.

Fixes: 17926a79320a ([AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both"")
Signed-off-by: David Howells
Signed-off-by: Greg Kroah-Hartman

afs: Don't unlock fetched data pages until the op completes successfully

2020-05-27T15:48:03+00:00

[ Upstream commit 9d1be4f4dc5ff1c66c86acfd2c35765d9e3776b3 ]

Don't call req->page_done() on each page as we finish filling it with
the data coming from the network.  Whilst this might speed up the
application a bit, it's a problem if there's a network failure and the
operation has to be reissued.

If this happens, an oops occurs because afs_readpages_page_done() clears
the pointer to each page it unlocks and when a retry happens, the
pointers to the pages it wants to fill are now NULL (and the pages have
been unlocked anyway).

Instead, wait till the operation completes successfully and only then
release all the pages after clearing any terminal gap (the server can
give us less data than we requested as we're allowed to ask for more
than is available).

KASAN produces a bug like the following, and even without KASAN, it can
oops and panic.

    BUG: KASAN: wild-memory-access in _copy_to_iter+0x323/0x5f4
    Write of size 1404 at addr 0005088000000000 by task md5sum/5235

    CPU: 0 PID: 5235 Comm: md5sum Not tainted 5.7.0-rc3-fscache+ #250
    Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014
    Call Trace:
     memcpy+0x39/0x58
     _copy_to_iter+0x323/0x5f4
     __skb_datagram_iter+0x89/0x2a6
     skb_copy_datagram_iter+0x129/0x135
     rxrpc_recvmsg_data.isra.0+0x615/0xd42
     rxrpc_kernel_recv_data+0x1e9/0x3ae
     afs_extract_data+0x139/0x33a
     yfs_deliver_fs_fetch_data64+0x47a/0x91b
     afs_deliver_to_call+0x304/0x709
     afs_wait_for_call_to_complete+0x1cc/0x4ad
     yfs_fs_fetch_data+0x279/0x288
     afs_fetch_data+0x1e1/0x38d
     afs_readpages+0x593/0x72e
     read_pages+0xf5/0x21e
     __do_page_cache_readahead+0x128/0x23f
     ondemand_readahead+0x36e/0x37f
     generic_file_buffered_read+0x234/0x680
     new_sync_read+0x109/0x17e
     vfs_read+0xe6/0x138
     ksys_read+0xd8/0x14d
     do_syscall_64+0x6e/0x8a
     entry_SYSCALL_64_after_hwframe+0x49/0xb3

Fixes: 196ee9cd2d04 ("afs: Make afs_fs_fetch_data() take a list of pages")
Fixes: 30062bd13e36 ("afs: Implement YFS support in the fs client")
Signed-off-by: David Howells 
Reviewed-by: Matthew Wilcox (Oracle) 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

afs: Fix length of dump of bad YFSFetchStatus record

2020-05-02T06:50:58+00:00

[ Upstream commit 3efe55b09a92a59ed8214db801683cf13c9742c4 ]

Fix the length of the dump of a bad YFSFetchStatus record.  The function
was copied from the AFS version, but the YFS variant contains bigger fields
and extra information, so expand the dump to match.

Signed-off-by: David Howells 
Signed-off-by: Sasha Levin

afs: Fix to actually set AFS_SERVER_FL_HAVE_EPOCH

2020-05-02T06:50:42+00:00

commit 69cf3978f3ada4e54beae4ad44868b5627864884 upstream.

AFS keeps track of the epoch value from the rxrpc protocol to note (a) when
a fileserver appears to have restarted and (b) when different endpoints of
a fileserver do not appear to be associated with the same fileserver
(ie. all probes back from a fileserver from all of its interfaces should
carry the same epoch).

However, the AFS_SERVER_FL_HAVE_EPOCH flag that indicates that we've
received the server's epoch is never set, though it is used.

Fix this to set the flag when we first receive an epoch value from a probe
sent to the filesystem client from the fileserver.

Fixes: 3bf0fb6f33dd ("afs: Probe multiple fileservers simultaneously")
Signed-off-by: David Howells 
Signed-off-by: Greg Kroah-Hartman

afs: Make record checking use TASK_UNINTERRUPTIBLE when appropriate

2020-05-02T06:50:41+00:00

commit c4bfda16d1b40d1c5941c61b5aa336bdd2d9904a upstream.

When an operation is meant to be done uninterruptibly (such as
FS.StoreData), we should not be allowing volume and server record checking
to be interrupted.

Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation")
Signed-off-by: David Howells 
Signed-off-by: Greg Kroah-Hartman

afs: Fix race between post-modification dir edit and readdir/d_revalidate

2020-04-23T08:37:57+00:00

commit 2105c2820d366b76f38e6ad61c75771881ecc532 upstream.

AFS directories are retained locally as a structured file, with lookup
being effected by a local search of the file contents.  When a modification
(such as mkdir) happens, the dir file content is modified locally rather
than redownloading the directory.

The directory contents are accessed in a number of ways, with a number of
different locks schemes:

 (1) Download of contents - dvnode->validate_lock/write in afs_read_dir().

 (2) Lookup and readdir - dvnode->validate_lock/read in afs_dir_iterate(),
     downgrading from (1) if necessary.

 (3) d_revalidate of child dentry - dvnode->validate_lock/read in
     afs_do_lookup_one() downgrading from (1) if necessary.

 (4) Edit of dir after modification - page locks on individual dir pages.

Unfortunately, because (4) uses different locking scheme to (1) - (3),
nothing protects against the page being scanned whilst the edit is
underway.  Even download is not safe as it doesn't lock the pages - relying
instead on the validate_lock to serialise as a whole (the theory being that
directory contents are treated as a block and always downloaded as a
block).

Fix this by write-locking dvnode->validate_lock around the edits.  Care
must be taken in the rename case as there may be two different dirs - but
they need not be locked at the same time.  In any case, once the lock is
taken, the directory version must be rechecked, and the edit skipped if a
later version has been downloaded by revalidation (there can't have been
any local changes because the VFS holds the inode lock, but there can have
been remote changes).

Fixes: 63a4681ff39c ("afs: Locally edit directory data for mkdir/create/unlink/...")
Signed-off-by: David Howells 
Signed-off-by: Greg Kroah-Hartman

afs: Fix afs_d_validate() to set the right directory version

2020-04-23T08:37:57+00:00

commit 40fc81027f892284ce31f8b6de1e497f5b47e71f upstream.

If a dentry's version is somewhere between invalid_before and the current
directory version, we should be setting it forward to the current version,
not backwards to the invalid_before version.  Note that we're only doing
this at all because dentry::d_fsdata isn't large enough on a 32-bit system.

Fix this by using a separate variable for invalid_before so that we don't
accidentally clobber the current dir version.

Fixes: a4ff7401fbfa ("afs: Keep track of invalid-before version for dentry coherency")
Signed-off-by: David Howells 
Signed-off-by: Greg Kroah-Hartman

afs: Fix rename operation status delivery

2020-04-23T08:37:56+00:00

commit b98f0ec91c42d87a70da42726b852ac8d78a3257 upstream.

The afs_deliver_fs_rename() and yfs_deliver_fs_rename() functions both only
decode the second file status returned unless the parent directories are
different - unfortunately, this means that the xdr pointer isn't advanced
and the volsync record will be read incorrectly in such an instance.

Fix this by always decoding the second status into the second
status/callback block which wasn't being used if the dirs were the same.

The afs_update_dentry_version() calls that update the directory data
version numbers on the dentries can then unconditionally use the second
status record as this will always reflect the state of the destination dir
(the two records will be identical if the destination dir is the same as
the source dir)

Fixes: 260a980317da ("[AFS]: Add "directory write" support.")
Fixes: 30062bd13e36 ("afs: Implement YFS support in the fs client")
Signed-off-by: David Howells 
Signed-off-by: Greg Kroah-Hartman

afs: Fix decoding of inline abort codes from version 1 status records

2020-04-23T08:37:56+00:00

commit 3e0d9892c0e7fa426ca6bf921cb4b543ca265714 upstream.

If we're decoding an AFSFetchStatus record and we see that the version is 1
and the abort code is set and we're expecting inline errors, then we store
the abort code and ignore the remaining status record (which is correct),
but we don't set the flag to say we got a valid abort code.

This can affect operation of YFS.RemoveFile2 when removing a file and the
operation of {,Y}FS.InlineBulkStatus when prospectively constructing or
updating of a set of inodes during a lookup.

Fix this to indicate the reception of a valid abort code.

Fixes: a38a75581e6e ("afs: Fix unlink to handle YFS.RemoveFile2 better")
Signed-off-by: David Howells 
Signed-off-by: Greg Kroah-Hartman

afs: Fix missing XDR advance in xdr_decode_{AFS,YFS}FSFetchStatus()

2020-04-23T08:37:56+00:00

commit c72057b56f7e24865840a6961d801a7f21d30a5f upstream.

If we receive a status record that has VNOVNODE set in the abort field,
xdr_decode_AFSFetchStatus() and xdr_decode_YFSFetchStatus() don't advance
the XDR pointer, thereby corrupting anything subsequent decodes from the
same block of data.

This has the potential to affect AFS.InlineBulkStatus and
YFS.InlineBulkStatus operation, but probably doesn't since the status
records are extracted as individual blocks of data and the buffer pointer
is reset between blocks.

It does affect YFS.RemoveFile2 operation, corrupting the volsync record -
though that is not currently used.

Other operations abort the entire operation rather than returning an error
inline, in which case there is no decoding to be done.

Fix this by unconditionally advancing the xdr pointer.

Fixes: 684b0f68cf1c ("afs: Fix AFSFetchStatus decoder to provide OpenAFS compatibility")
Signed-off-by: David Howells 
Signed-off-by: Greg Kroah-Hartman