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nfsd: Fix a write performance regression

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The call to filemap_flush() in nfsd_file_put() is there to ensure that
we clear out any writes belonging to a NFSv3 client relatively quickly
and avoid situations where the file can't be evicted by the garbage
collector. It also ensures that we detect write errors quickly.

The problem is this causes a regression in performance for some
workloads.

So try to improve matters by deferring writeback until we're ready to
close the file, and need to detect errors so that we can force the
client to resend.

Tested-by: Jan Kara <jack@suse.cz>
Fixes: b6669305d35a ("nfsd: Reduce the number of calls to nfsd_file_gc()")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Link: https://lore.kernel.org/all/20220330103457.r4xrhy2d6nhtouzk@quack3.lan
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Trond Myklebust 2022-03-31 09:54:01 -04:00 committed by Chuck Lever
parent 5f7b839d47
commit 6b8a94332e
1 changed files with 15 additions and 3 deletions
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18
fs/nfsd/filecache.c
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@ -235,6 +235,13 @@ nfsd_file_check_write_error(struct nfsd_file *nf)
return filemap_check_wb_err(file->f_mapping, READ_ONCE(file->f_wb_err));
}
static void
nfsd_file_flush(struct nfsd_file *nf)
{
if (nf->nf_file && vfs_fsync(nf->nf_file, 1) != 0)
nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id));
}
static void
nfsd_file_do_unhash(struct nfsd_file *nf)
{
@ -302,11 +309,14 @@ nfsd_file_put(struct nfsd_file *nf)
return;
}
filemap_flush(nf->nf_file->f_mapping);
is_hashed = test_bit(NFSD_FILE_HASHED, &nf->nf_flags) != 0;
nfsd_file_put_noref(nf);
if (is_hashed)
if (!is_hashed) {
nfsd_file_flush(nf);
nfsd_file_put_noref(nf);
} else {
nfsd_file_put_noref(nf);
nfsd_file_schedule_laundrette();
}
if (atomic_long_read(&nfsd_filecache_count) >= NFSD_FILE_LRU_LIMIT)
nfsd_file_gc();
}
@ -327,6 +337,7 @@ nfsd_file_dispose_list(struct list_head *dispose)
while(!list_empty(dispose)) {
nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
list_del(&nf->nf_lru);
nfsd_file_flush(nf);
nfsd_file_put_noref(nf);
}
}
@ -340,6 +351,7 @@ nfsd_file_dispose_list_sync(struct list_head *dispose)
while(!list_empty(dispose)) {
nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
list_del(&nf->nf_lru);
nfsd_file_flush(nf);
if (!refcount_dec_and_test(&nf->nf_ref))
continue;
if (nfsd_file_free(nf))