From: bfields@fieldses.org (J. Bruce Fields)
To: Trond Myklebust <trondmy@gmail.com>
Cc: "J. Bruce Fields" <bfields@redhat.com>, linux-nfs@vger.kernel.org
Subject: Re: [PATCH 0/9] Fix error reporting for NFS writes
Date: Wed, 22 Jan 2020 10:27:51 -0500 [thread overview]
Message-ID: <20200122152751.GD2654@fieldses.org> (raw)
In-Reply-To: <20200106184037.563557-1-trond.myklebust@hammerspace.com>
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
next prev parent reply other threads:[~2020-01-22 15:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-06 18:40 [PATCH 0/9] Fix error reporting for NFS writes Trond Myklebust
2020-01-06 18:40 ` [PATCH 1/9] nfsd: Allow nfsd_vfs_write() to take the nfsd_file as an argument Trond Myklebust
2020-01-06 18:40 ` [PATCH 2/9] nfsd: Fix stable writes Trond Myklebust
2020-01-06 18:40 ` [PATCH 3/9] nfsd: Update the boot verifier on stable writes too Trond Myklebust
2020-01-06 18:40 ` [PATCH 4/9] nfsd: Pass the nfsd_file as arguments to nfsd4_clone_file_range() Trond Myklebust
2020-01-06 18:40 ` [PATCH 5/9] nfsd: Ensure exclusion between CLONE and WRITE errors Trond Myklebust
2020-01-06 18:40 ` [PATCH 6/9] sunrpc: Fix potential leaks in sunrpc_cache_unhash() Trond Myklebust
2020-01-06 18:40 ` [PATCH 7/9] sunrpc: clean up cache entry add/remove from hashtable Trond Myklebust
2020-01-06 18:40 ` [PATCH 8/9] nfsd: Ensure sampling of the commit verifier is atomic with the commit Trond Myklebust
2020-01-06 18:40 ` [PATCH 9/9] nfsd: Ensure sampling of the write verifier is atomic with the write Trond Myklebust
2020-01-22 15:27 ` J. Bruce Fields [this message]
2020-01-22 17:04 ` [PATCH 0/9] Fix error reporting for NFS writes J. Bruce Fields
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