From: "Benjamin Coddington" <bcodding@redhat.com>
To: "Trond Myklebust" <trondmy@hammerspace.com>
Cc: dwysocha@redhat.com, linux-nfs@vger.kernel.org
Subject: Re: [PATCH v5 00/22] Readdir enhancements
Date: Thu, 12 Nov 2020 13:39:01 -0500 [thread overview]
Message-ID: <DC49EB88-4B79-40FC-97C3-47D2A588F96C@redhat.com> (raw)
In-Reply-To: <6b07ff95824f5b46237fa07f5f72d8261d764007.camel@hammerspace.com>
On 12 Nov 2020, at 13:26, Trond Myklebust wrote:
> On Thu, 2020-11-12 at 16:51 +0000, Trond Myklebust wrote:
>>
>> I was going to ask you if perhaps reverting Scott's commit
>> 07b5ce8ef2d8
>> ("NFS: Make nfs_readdir revalidate less often") might help here?
>> My thinking is that will trigger more cache invalidations when the
>> directory is changing underneath us, and will now trigger uncached
>> readdir in those situations.
>>
>>>
>
> IOW, the suggestion would be to apply something like the following on
> top of the existing readdir patchset:
I'm all for this approach, but - I'm rarely seeing the mapping->nrpages == 0
since the cache is dropped by a process in nfs_readdir() that immediately
starts filling the cache again.
It would make a lot more sense to me if we could do something like stash
desc->page_index << PAGE_SHIFT in f_pos after each nfs_readdir, then the
hueristic could check f_pos >> PAGE_SHIFT > nrpages.
Yes, f_pos is growing many different meanings in NFS directories, maybe we
can stash it on the directory context.
Ben
>
> ---
> fs/nfs/dir.c | 14 ++++++--------
> 1 file changed, 6 insertions(+), 8 deletions(-)
>
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index 3f70697729d8..384a4663f742 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -956,10 +956,10 @@ static int readdir_search_pagecache(struct
> nfs_readdir_descriptor *desc)
> {
> int res;
>
> - if (nfs_readdir_dont_search_cache(desc))
> - return -EBADCOOKIE;
> -
> do {
> + if (nfs_readdir_dont_search_cache(desc))
> + return -EBADCOOKIE;
> +
> if (desc->page_index == 0) {
> desc->current_index = 0;
> desc->prev_index = 0;
> @@ -1082,11 +1082,9 @@ static int nfs_readdir(struct file *file, struct
> dir_context *ctx)
> * to either find the entry with the appropriate number or
> * revalidate the cookie.
> */
> - if (ctx->pos == 0 || nfs_attribute_cache_expired(inode)) {
> - res = nfs_revalidate_mapping(inode, file->f_mapping);
> - if (res < 0)
> - goto out;
> - }
> + res = nfs_revalidate_mapping(inode, file->f_mapping);
> + if (res < 0)
> + goto out;
>
> res = -ENOMEM;
> desc = kzalloc(sizeof(*desc), GFP_KERNEL);
>
>
> --
> Trond Myklebust
> Linux NFS client maintainer, Hammerspace
> trond.myklebust@hammerspace.com
next prev parent reply other threads:[~2020-11-12 18:39 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-10 21:37 [PATCH v5 00/22] Readdir enhancements trondmy
2020-11-10 21:37 ` [PATCH v5 01/22] NFS: Remove unnecessary inode locking in nfs_llseek_dir() trondmy
2020-11-10 21:37 ` [PATCH v5 02/22] NFS: Remove unnecessary inode lock in nfs_fsync_dir() trondmy
2020-11-10 21:37 ` [PATCH v5 03/22] NFSv4.2: condition READDIR's mask for security label based on LSM state trondmy
2020-11-10 21:37 ` [PATCH v5 04/22] NFS: Ensure contents of struct nfs_open_dir_context are consistent trondmy
2020-11-10 21:37 ` [PATCH v5 05/22] NFS: Clean up readdir struct nfs_cache_array trondmy
2020-11-10 21:37 ` [PATCH v5 06/22] NFS: Clean up nfs_readdir_page_filler() trondmy
2020-11-10 21:37 ` [PATCH v5 07/22] NFS: Clean up directory array handling trondmy
2020-11-10 21:37 ` [PATCH v5 08/22] NFS: Don't discard readdir results trondmy
2020-11-10 21:37 ` [PATCH v5 09/22] NFS: Remove unnecessary kmap in nfs_readdir_xdr_to_array() trondmy
2020-11-10 21:37 ` [PATCH v5 10/22] NFS: Replace kmap() with kmap_atomic() in nfs_readdir_search_array() trondmy
2020-11-10 21:37 ` [PATCH v5 11/22] NFS: Simplify struct nfs_cache_array_entry trondmy
2020-11-10 21:37 ` [PATCH v5 12/22] NFS: Support larger readdir buffers trondmy
2020-11-10 21:37 ` [PATCH v5 13/22] NFS: More readdir cleanups trondmy
2020-11-10 21:37 ` [PATCH v5 14/22] NFS: nfs_do_filldir() does not return a value trondmy
2020-11-10 21:37 ` [PATCH v5 15/22] NFS: Reduce readdir stack usage trondmy
2020-11-10 21:37 ` [PATCH v5 16/22] NFS: Cleanup to remove nfs_readdir_descriptor_t typedef trondmy
2020-11-10 21:37 ` [PATCH v5 17/22] NFS: Allow the NFS generic code to pass in a verifier to readdir trondmy
2020-11-10 21:37 ` [PATCH v5 18/22] NFS: Handle NFS4ERR_NOT_SAME and NFSERR_BADCOOKIE from readdir calls trondmy
2020-11-10 21:37 ` [PATCH v5 19/22] NFS: Improve handling of directory verifiers trondmy
2020-11-10 21:37 ` [PATCH v5 20/22] NFS: Optimisations for monotonically increasing readdir cookies trondmy
2020-11-10 21:37 ` [PATCH v5 21/22] NFS: Reduce number of RPC calls when doing uncached readdir trondmy
2020-11-10 21:37 ` [PATCH v5 22/22] NFS: Do uncached readdir when we're seeking a cookie in an empty page cache trondmy
2020-11-11 22:15 ` [PATCH v5 00/22] Readdir enhancements David Wysochanski
2020-11-12 11:41 ` David Wysochanski
2020-11-12 15:34 ` Guy Keren
2020-11-12 16:54 ` Trond Myklebust
2020-11-12 16:51 ` Trond Myklebust
2020-11-12 18:26 ` Trond Myklebust
2020-11-12 18:39 ` Benjamin Coddington [this message]
2020-11-12 18:49 ` Benjamin Coddington
2020-11-12 19:04 ` Trond Myklebust
2020-11-12 19:09 ` Benjamin Coddington
2020-11-12 20:23 ` Benjamin Coddington
2020-11-13 11:09 ` Mkrtchyan, Tigran
2020-11-14 13:32 ` David Wysochanski
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