By the way, anyone know how to handle quoted-printable patches? For some reason, git-am seems to deal with them, but git-apply doesn't. So it's fine until there's some minor conflict. --b. On Mon, Jan 06, 2020 at 01:40:28PM -0500, Trond Myklebust wrote: > In cases where we have transient errors, such as ENOSPC, it is important > to ensure that errors are reported on all writes that may be affected. > > The problem we have is that not all errors are guaranteed to be reported > at write time. Some are reported only when we call fsync(). In > particular, this can be a problem for stable NFS writes. Since most > filesystems protect the write to the page cache with the inode lock, > but do not protect the subsequent call to generic_write_sync(), this > means that if we have parallel writes to the same file, we can end up > assigning the error to the wrong stable write call. If the application > expects to be able to fix the transient errors, it may end up replaying > the wrong write. One area where we have seen this happen is in flexfiles > writes, where the server is capable of freeing up space on the DS in > case of ENOSPC. > > The other area where we have seen a similar problem is when we have > unstable writes, and the client sends a backgrounded commit in order > to free up memory. If there are outstanding writes while the commit > gets a transient error and bumps the write verifier, then we want to > ensure that those writes get the approprite write verifier depending > on whether they were affected by the fsync() or not. Right now, > because the NFSv3 verifier is set in the XDR encoder well after the > write is done, there is fairly large window for a race with a > background commit. > > This patch series deals with both issues by adding per-file-descriptor > locking that ensures that writes, fsync error handling, and write verifier > updates are appropriately serialised. > > Trond Myklebust (9): > nfsd: Allow nfsd_vfs_write() to take the nfsd_file as an argument > nfsd: Fix stable writes > nfsd: Update the boot verifier on stable writes too. > nfsd: Pass the nfsd_file as arguments to nfsd4_clone_file_range() > nfsd: Ensure exclusion between CLONE and WRITE errors > sunrpc: Fix potential leaks in sunrpc_cache_unhash() > sunrpc: clean up cache entry add/remove from hashtable > nfsd: Ensure sampling of the commit verifier is atomic with the commit > nfsd: Ensure sampling of the write verifier is atomic with the write > > fs/nfsd/filecache.c | 1 + > fs/nfsd/filecache.h | 1 + > fs/nfsd/nfs3proc.c | 5 +-- > fs/nfsd/nfs3xdr.c | 16 +++------ > fs/nfsd/nfs4proc.c | 14 ++++---- > fs/nfsd/nfsproc.c | 2 +- > fs/nfsd/vfs.c | 79 ++++++++++++++++++++++++++++++++++----------- > fs/nfsd/vfs.h | 16 +++++---- > fs/nfsd/xdr3.h | 2 ++ > net/sunrpc/cache.c | 48 ++++++++++++++------------- > 10 files changed, 115 insertions(+), 69 deletions(-) > > -- > 2.24.1
