kernel.git/fs/nfs, branch linux-5.16.y

NFSv4: fix open failure with O_ACCMODE flag

2022-04-13T18:03:12Z

[ Upstream commit b243874f6f9568b2daf1a00e9222cacdc15e159c ] open() with O_ACCMODE|O_DIRECT flags secondly will fail. Reproducer: 1. mount -t nfs -o vers=4.2 $server_ip:/ /mnt/ 2. fd = open("/mnt/file", O_ACCMODE|O_DIRECT|O_CREAT) 3. close(fd) 4. fd = open("/mnt/file", O_ACCMODE|O_DIRECT) Server nfsd4_decode_share_access() will fail with error nfserr_bad_xdr when client use incorrect share access mode of 0. Fix this by using NFS4_SHARE_ACCESS_BOTH share access mode in client, just like firstly opening. Fixes: ce4ef7c0a8a05 ("NFS: Split out NFS v4 file operations") Signed-off-by: ChenXiaoSong Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

Revert "NFSv4: Handle the special Linux file open access mode"

2022-04-13T18:03:12Z

[ Upstream commit ab0fc21bc7105b54bafd85bd8b82742f9e68898a ] This reverts commit 44942b4e457beda00981f616402a1a791e8c616e. After secondly opening a file with O_ACCMODE|O_DIRECT flags, nfs4_valid_open_stateid() will dereference NULL nfs4_state when lseek(). Reproducer: 1. mount -t nfs -o vers=4.2 $server_ip:/ /mnt/ 2. fd = open("/mnt/file", O_ACCMODE|O_DIRECT|O_CREAT) 3. close(fd) 4. fd = open("/mnt/file", O_ACCMODE|O_DIRECT) 5. lseek(fd) Reported-by: Lyu Tao Signed-off-by: ChenXiaoSong Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

NFS: Avoid writeback threads getting stuck in mempool_alloc()

2022-04-13T18:03:11Z

[ Upstream commit 0bae835b63c53f86cdc524f5962e39409585b22c ] In a low memory situation, allow the NFS writeback code to fail without getting stuck in infinite loops in mempool_alloc(). Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

NFS: nfsiod should not block forever in mempool_alloc()

2022-04-13T18:03:11Z

[ Upstream commit 515dcdcd48736576c6f5c197814da6f81c60a21e ] The concern is that since nfsiod is sometimes required to kick off a commit, it can get locked up waiting forever in mempool_alloc() instead of failing gracefully and leaving the commit until later. Try to allocate from the slab first, with GFP_KERNEL | __GFP_NORETRY, then fall back to a non-blocking attempt to allocate from the memory pool. Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

NFS: swap-out must always use STABLE writes.

2022-04-13T18:03:10Z

[ Upstream commit c265de257f558a05c1859ee9e3fed04883b9ec0e ] The commit handling code is not safe against memory-pressure deadlocks when writing to swap. In particular, nfs_commitdata_alloc() blocks indefinitely waiting for memory, and this can consume all available workqueue threads. swap-out most likely uses STABLE writes anyway as COND_STABLE indicates that a stable write should be used if the write fits in a single request, and it normally does. However if we ever swap with a small wsize, or gather unusually large numbers of pages for a single write, this might change. For safety, make it explicit in the code that direct writes used for swap must always use FLUSH_STABLE. Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

NFS: swap IO handling is slightly different for O_DIRECT IO

2022-04-13T18:03:10Z

[ Upstream commit 64158668ac8b31626a8ce48db4cad08496eb8340 ] 1/ Taking the i_rwsem for swap IO triggers lockdep warnings regarding possible deadlocks with "fs_reclaim". These deadlocks could, I believe, eventuate if a buffered read on the swapfile was attempted. We don't need coherence with the page cache for a swap file, and buffered writes are forbidden anyway. There is no other need for i_rwsem during direct IO. So never take it for swap_rw() 2/ generic_write_checks() explicitly forbids writes to swap, and performs checks that are not needed for swap. So bypass it for swap_rw(). Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

NFSv4: Protect the state recovery thread against direct reclaim

2022-04-13T18:03:09Z

[ Upstream commit 3e17898aca293a24dae757a440a50aa63ca29671 ] If memory allocation triggers a direct reclaim from the state recovery thread, then we can deadlock. Use memalloc_nofs_save/restore to ensure that doesn't happen. Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

NFSv4.2: fix reference count leaks in _nfs42_proc_copy_notify()

2022-04-13T18:03:09Z

[ Upstream commit b7f114edd54326f730a754547e7cfb197b5bc132 ] [You don't often get email from xiongx18@fudan.edu.cn. Learn why this is important at http://aka.ms/LearnAboutSenderIdentification.] The reference counting issue happens in two error paths in the function _nfs42_proc_copy_notify(). In both error paths, the function simply returns the error code and forgets to balance the refcount of object `ctx`, bumped by get_nfs_open_context() earlier, which may cause refcount leaks. Fix it by balancing refcount of the `ctx` object before the function returns in both error paths. Signed-off-by: Xin Xiong Signed-off-by: Xiyu Yang Signed-off-by: Xin Tan Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

NFSv4/pNFS: Fix another issue with a list iterator pointing to the head

2022-04-08T12:06:31Z

[ Upstream commit 7c9d845f0612e5bcd23456a2ec43be8ac43458f1 ] In nfs4_callback_devicenotify(), if we don't find a matching entry for the deviceid, we're left with a pointer to 'struct nfs_server' that actually points to the list of super blocks associated with our struct nfs_client. Furthermore, even if we have a valid pointer, nothing pins the super block, and so the struct nfs_server could end up getting freed while we're using it. Since all we want is a pointer to the struct pnfs_layoutdriver_type, let's skip all the iteration over super blocks, and just use APIs to find the layout driver directly. Reported-by: Xiaomeng Tong Fixes: 1be5683b03a7 ("pnfs: CB_NOTIFY_DEVICEID") Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

NFS: Don't loop forever in nfs_do_recoalesce()

2022-04-08T12:06:30Z

[ Upstream commit d02d81efc7564b4d5446a02e0214a164cf00b1f3 ] If __nfs_pageio_add_request() fails to add the request, it will return with either desc->pg_error < 0, or mirror->pg_recoalesce will be set, so we are guaranteed either to exit the function altogether, or to loop. However if there is nothing left in mirror->pg_list to coalesce, we must exit, so make sure that we clear mirror->pg_recoalesce every time we loop. Reported-by: Olga Kornievskaia Fixes: 70536bf4eb07 ("NFS: Clean up reset of the mirror accounting variables") Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin