kernel/git/stable/linux.git/fs/afs/dir.c, branch linux-4.16.y

afs: Support the AFS dynamic root

2018-02-06T14:43:37+00:00

Support the AFS dynamic root which is a pseudo-volume that doesn't connect to any server resource, but rather is just a root directory that dynamically creates mountpoint directories where the name of such a directory is the name of the cell. Such a mount can be created thus: mount -t afs none /afs -o dyn Dynamic root superblocks aren't shared except by bind mounts and propagation. Cell root volumes can then be mounted by referring to them by name, e.g.: ls /afs/grand.central.org/ ls /afs/.grand.central.org/ The kernel will upcall to consult the DNS if the address wasn't supplied directly. Signed-off-by: David Howells

afs: Fix unlink

2018-01-02T10:02:19+00:00

Repeating creation and deletion of a file on an afs mount will run the box out of memory, e.g.: dd if=/dev/zero of=/afs/scratch/m0 bs=$((1024*1024)) count=512 rm /afs/scratch/m0 The problem seems to be that it's not properly decrementing the nlink count so that the inode can be scrapped. Note that this doesn't fix local creation followed by remote deletion. That's harder to handle and will require a separate patch as we're not told that the file has been deleted - only that the directory has changed. Reported-by: Marc Dionne Signed-off-by: David Howells

afs: remove redundant assignment of dvnode to itself

2017-11-24T13:55:46+00:00

The assignment of dvnode to itself is redundant and can be removed. Cleans up warning detected by cppcheck: fs/afs/dir.c:975: (warning) Redundant assignment of 'dvnode' to itself. Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation") Signed-off-by: Colin Ian King Signed-off-by: David Howells

afs: Fix signal handling in some file ops

2017-11-24T13:55:35+00:00

afs_mkdir(), afs_create(), afs_link() and afs_symlink() all need to drop the target dentry if a signal causes the operation to be killed immediately before we try to contact the server. Signed-off-by: David Howells

afs: Fix some dentry handling in dir ops and missing key_puts

2017-11-24T10:56:51+00:00

Fix some of dentry handling in AFS directory ops: (1) Do d_drop() on the new_dentry before assigning a new inode to it in afs_vnode_new_inode(). It's fine to do this before calling afs_iget() because the operation has taken place on the server. (2) Replace d_instantiate()/d_rehash() with d_add(). (3) Don't d_drop() the new_dentry in afs_rename() on error. Also fix afs_link() and afs_rename() to call key_put() on all error paths where the key is taken. Signed-off-by: David Howells

afs: Introduce a file-private data record

2017-11-13T15:38:20+00:00

Introduce a file-private data record for kAFS and put the key into it rather than storing the key in file->private_data. Signed-off-by: David Howells

afs: Fix directory read/modify race

2017-11-13T15:38:20+00:00

Because parsing of the directory wasn't being done under any sort of lock, the pages holding the directory content can get invalidated whilst the parsing is ongoing. Further, the directory page check function gets called outside of the page lock, so if the page gets cleared or updated, this may return reports of bad magic numbers in the directory page. Also, the directory may change size whilst checking and parsing are ongoing, so more care needs to be taken here. Fix this by: (1) Perform the page check from the page filling function before we set PageUptodate and drop the page lock. (2) Check for the file having shrunk and the page having been abandoned before checking the page contents. (3) Lock the page whilst parsing it for the directory iterator. Whilst we're at it, add a tracepoint to report check failure. Signed-off-by: David Howells

afs: Overhaul volume and server record caching and fileserver rotation

2017-11-13T15:38:19+00:00

The current code assumes that volumes and servers are per-cell and are never shared, but this is not enforced, and, indeed, public cells do exist that are aliases of each other. Further, an organisation can, say, set up a public cell and a private cell with overlapping, but not identical, sets of servers. The difference is purely in the database attached to the VL servers. The current code will malfunction if it sees a server in two cells as it assumes global address -> server record mappings and that each server is in just one cell. Further, each server may have multiple addresses - and may have addresses of different families (IPv4 and IPv6, say). To this end, the following structural changes are made: (1) Server record management is overhauled: (a) Server records are made independent of cell. The namespace keeps track of them, volume records have lists of them and each vnode has a server on which its callback interest currently resides. (b) The cell record no longer keeps a list of servers known to be in that cell. (c) The server records are now kept in a flat list because there's no single address to sort on. (d) Server records are now keyed by their UUID within the namespace. (e) The addresses for a server are obtained with the VL.GetAddrsU rather than with VL.GetEntryByName, using the server's UUID as a parameter. (f) Cached server records are garbage collected after a period of non-use and are counted out of existence before purging is allowed to complete. This protects the work functions against rmmod. (g) The servers list is now in /proc/fs/afs/servers. (2) Volume record management is overhauled: (a) An RCU-replaceable server list is introduced. This tracks both servers and their coresponding callback interests. (b) The superblock is now keyed on cell record and numeric volume ID. (c) The volume record is now tied to the superblock which mounts it, and is activated when mounted and deactivated when unmounted. This makes it easier to handle the cache cookie without causing a double-use in fscache. (d) The volume record is loaded from the VLDB using VL.GetEntryByNameU to get the server UUID list. (e) The volume name is updated if it is seen to have changed when the volume is updated (the update is keyed on the volume ID). (3) The vlocation record is got rid of and VLDB records are no longer cached. Sufficient information is stored in the volume record, though an update to a volume record is now no longer shared between related volumes (volumes come in bundles of three: R/W, R/O and backup). and the following procedural changes are made: (1) The fileserver cursor introduced previously is now fleshed out and used to iterate over fileservers and their addresses. (2) Volume status is checked during iteration, and the server list is replaced if a change is detected. (3) Server status is checked during iteration, and the address list is replaced if a change is detected. (4) The abort code is saved into the address list cursor and -ECONNABORTED returned in afs_make_call() if a remote abort happened rather than translating the abort into an error message. This allows actions to be taken depending on the abort code more easily. (a) If a VMOVED abort is seen then this is handled by rechecking the volume and restarting the iteration. (b) If a VBUSY, VRESTARTING or VSALVAGING abort is seen then this is handled by sleeping for a short period and retrying and/or trying other servers that might serve that volume. A message is also displayed once until the condition has cleared. (c) If a VOFFLINE abort is seen, then this is handled as VBUSY for the moment. (d) If a VNOVOL abort is seen, the volume is rechecked in the VLDB to see if it has been deleted; if not, the fileserver is probably indicating that the volume couldn't be attached and needs salvaging. (e) If statfs() sees one of these aborts, it does not sleep, but rather returns an error, so as not to block the umount program. (5) The fileserver iteration functions in vnode.c are now merged into their callers and more heavily macroised around the cursor. vnode.c is removed. (6) Operations on a particular vnode are serialised on that vnode because the server will lock that vnode whilst it operates on it, so a second op sent will just have to wait. (7) Fileservers are probed with FS.GetCapabilities before being used. This is where service upgrade will be done. (8) A callback interest on a fileserver is set up before an FS operation is performed and passed through to afs_make_call() so that it can be set on the vnode if the operation returns a callback. The callback interest is passed through to afs_iget() also so that it can be set there too. In general, record updating is done on an as-needed basis when we try to access servers, volumes or vnodes rather than offloading it to work items and special threads. Notes: (1) Pre AFS-3.4 servers are no longer supported, though this can be added back if necessary (AFS-3.4 was released in 1998). (2) VBUSY is retried forever for the moment at intervals of 1s. (3) /proc/fs/afs//servers no longer exists. Signed-off-by: David Howells

afs: Overhaul the callback handling

2017-11-13T15:38:18+00:00

Overhaul the AFS callback handling by the following means: (1) Don't give up callback promises on vnodes that we are no longer using, rather let them just expire on the server or let the server break them. This is actually more efficient for the server as the callback lookup is expensive if there are lots of extant callbacks. (2) Only give up the callback promises we have from a server when the server record is destroyed. Then we can just give up *all* the callback promises on it in one go. (3) Servers can end up being shared between cells if cells are aliased, so don't add all the vnodes being backed by a particular server into a big FID-indexed tree on that server as there may be duplicates. Instead have each volume instance (~= superblock) register an interest in a server as it starts to make use of it and use this to allow the processor for callbacks from the server to find the superblock and thence the inode corresponding to the FID being broken by means of ilookup_nowait(). (4) Rather than iterating over the entire callback list when a mass-break comes in from the server, maintain a counter of mass-breaks in afs_server (cb_seq) and make afs_validate() check it against the copy in afs_vnode. It would be nice not to have to take a read_lock whilst doing this, but that's tricky without using RCU. (5) Save a ref on the fileserver we're using for a call in the afs_call struct so that we can access its cb_s_break during call decoding. (6) Write-lock around callback and status storage in a vnode and read-lock around getattr so that we don't see the status mid-update. This has the following consequences: (1) Data invalidation isn't seen until someone calls afs_validate() on a vnode. Unfortunately, we need to use a key to query the server, but getting one from a background thread is tricky without caching loads of keys all over the place. (2) Mass invalidation isn't seen until someone calls afs_validate(). (3) Callback breaking is going to hit the inode_hash_lock quite a bit. Could this be replaced with rcu_read_lock() since inodes are destroyed under RCU conditions. Signed-off-by: David Howells

afs: Push the net ns pointer to more places

2017-11-13T15:38:17+00:00

Push the network namespace pointer to more places in AFS, including the afs_server structure (which doesn't hold a ref on the netns). In particular, afs_put_cell() now takes requires a net ns parameter so that it can safely alter the netns after decrementing the cell usage count - the cell will be deallocated by a background thread after being cached for a period, which means that it's not safe to access it after reducing its usage count. Signed-off-by: David Howells