kernel.git/fs/nfs/write.c, branch linux-3.18.y

NFS: Add a cond_resched() to nfs_commit_release_pages()

2018-02-16T19:14:44Z

commit 7f1bda447c9bd48b415acedba6b830f61591601f upstream. The commit list can get very large, and so we need a cond_resched() in nfs_commit_release_pages() in order to ensure we don't hog the CPU for excessive periods of time. Reported-by: Mike Galbraith Signed-off-by: Trond Myklebust Signed-off-by: Greg Kroah-Hartman

nfs: don't create zero-length requests

2016-08-22T16:23:16Z

[ Upstream commit 149a4fddd0a72d526abbeac0c8deaab03559836a ] NFS doesn't expect requests with wb_bytes set to zero and may make unexpected decisions about how to handle that request at the page IO layer. Skip request creation if we won't have any wb_bytes in the request. Signed-off-by: Benjamin Coddington Signed-off-by: Alexey Dobriyan Reviewed-by: Weston Andros Adamson Cc: stable@vger.kernel.org Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

NFS: Ensure we set NFS_CONTEXT_RESEND_WRITES when requeuing writes

2015-07-04T03:02:33Z

[ Upstream commit c70701131f7a8edea91fc49d11796d342cff7c62 ] If a write attempt fails, and the write is queued up for resending to the server, as opposed to being dropped, then we need to set the appropriate flag so that nfs_file_fsync() does the right thing. Cc: stable@vger.kernel.org Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

nfs: remove spurious WARN_ON_ONCE in write path

2014-11-12T19:22:52Z

This WARN_ON_ONCE was supposed to catch reference counting bugs, but can trigger in inappropriate situations. This was reproducible using NFSv2 on an architecture with 64K pages -- we verified that it was not a reference counting bug and the warning was safe to ignore. Reported-by: Will Deacon Tested-by: Will Deacon Signed-off-by: Weston Andros Adamson Signed-off-by: Trond Myklebust

NFS: avoid waiting at all in nfs_release_page when congested.

2014-09-25T12:25:38Z

If nfs_release_page() is called on a sequence of pages which are all in the same file which is blocked on COMMIT, each page could contribute a 1 second delay which could be come excessive. I have seen delays of as much as 208 seconds. To keep the delay to one second, mark the bdi as write-congested if the commit didn't finished. Once it does finish, the write-congested flag will be cleared by nfs_commit_release_pages(). With this, the longest total delay in try_to_free_pages that I have seen is under 3 seconds. With no waiting in nfs_release_page at all I have seen delays of nearly 1.5 seconds. Signed-off-by: NeilBrown Acked-by: Jeff Layton Signed-off-by: Trond Myklebust

NFS: avoid deadlocks with loop-back mounted NFS filesystems.

2014-09-25T12:25:28Z

Support for loop-back mounted NFS filesystems is useful when NFS is used to access shared storage in a high-availability cluster. If the node running the NFS server fails, some other node can mount the filesystem and start providing NFS service. If that node already had the filesystem NFS mounted, it will now have it loop-back mounted. nfsd can suffer a deadlock when allocating memory and entering direct reclaim. While direct reclaim does not write to the NFS filesystem it can send and wait for a COMMIT through nfs_release_page(). This patch modifies nfs_release_page() to wait a limited time for the commit to complete - one second. If the commit doesn't complete in this time, nfs_release_page() will fail. This means it might now fail in some cases where it wouldn't before. These cases are only when 'gfp' includes '__GFP_WAIT'. nfs_release_page() is only called by try_to_release_page(), and that can only be called on an NFS page with required 'gfp' flags from - page_cache_pipe_buf_steal() in splice.c - shrink_page_list() in vmscan.c - invalidate_inode_pages2_range() in truncate.c The first two handle failure quite safely. The last is only called after ->launder_page() has been called, and that will have waited for the commit to finish already. So aborting if the commit takes longer than 1 second is perfectly safe. Signed-off-by: NeilBrown Acked-by: Jeff Layton Signed-off-by: Trond Myklebust

NFS: don't use STABLE writes during writeback.

2014-09-25T03:23:02Z

commit b31268ac793fd300da66b9c28bbf0a200339ab96 FS: Use stable writes when not doing a bulk flush was a bit heavy handed. The particular problem that lead to this patch was that small writes to an O_SYNC file we being written as UNSTABLE writes followed by a commit. This is appropriate for large writes (which require multiple NFS requests) but for small writes (single NFS request), using NFS_FILE_SYNC is more efficient. So that patch causes the code to select between the two methods depending on how many nfs requests get generated. Unfortunately this ends up applying to non O_SYNC writes as well. In particular if you memory-map a file and update random pages, then when they are eventually written out by writeback they will go as NFS_FILE_SYNC. This is inefficient and slows down the application. So: only set FLUSH_COND_STABLE when wbc->sync_mode is WB_SYNC_ALL. With this patch: O_SYNC writes are NFS_FILE_SYNC for single requests, and NFS_UNSTABLE followed by COMMIT for multiple requests Writing immediately before close of fsync follow the same pattern. Non-O_SYNC writes without an fsync of close eventually get flushed out as UNSTABLE and a commit follows eventually as appropriate. Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust

NFS: Unconditionally enable commit code

2014-09-12T17:49:31Z

The goal is to create a generic NFS module with code that does not depend on what versions of NFS are enabled. Signed-off-by: Anna Schumaker Signed-off-by: Trond Myklebust

NFS: Fix a compile warning when !(CONFIG_NFS_V3 || CONFIG_NFS_V4)

2014-09-10T19:47:02Z

gcc reports: linux/fs/nfs/write.c: In function ‘nfs_page_find_head_request_locked.isra.17’: linux/fs/nfs/write.c:121:64: warning: ‘cinfo.mds’ may be used uninitialized in this function [-Wmaybe-uninitialized] list_for_each_entry_safe(freq, t, &cinfo.mds->list, wb_list) { ^ linux/fs/nfs/write.c:110:25: note: ‘cinfo.mds’ was declared here struct nfs_commit_info cinfo; Reported-by: Anna Schumaker Cc: Weston Andros Adamson Signed-off-by: Trond Myklebust

nfs41: add a helper function to set layoutcommit after commit

2014-09-10T19:47:00Z

Track lwb in nfs_commit_data so that we can use it to setup layoutcommit in commit_done callback. Signed-off-by: Peng Tao Signed-off-by: Trond Myklebust