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nfsd: Reduce contention for the nfsd_file nf_rwsem

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When flushing out the unstable file writes as part of a COMMIT call, try
to perform most of of the data writes and waits outside the semaphore.

This means that if the client is sending the COMMIT as part of a memory
reclaim operation, then it can continue performing I/O, with contention
for the lock occurring only once the data sync is finished.

Fixes: 5011af4c698a ("nfsd: Fix stable writes")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
 Tested-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Trond Myklebust 2021-06-17 19:26:52 -04:00 committed by J. Bruce Fields
parent 0ff5b50ab1
commit 474bc33469
1 changed files with 16 additions and 2 deletions
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18
fs/nfsd/vfs.c
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@ -1123,6 +1123,19 @@ out:
}
#ifdef CONFIG_NFSD_V3
static int
nfsd_filemap_write_and_wait_range(struct nfsd_file *nf, loff_t offset,
loff_t end)
{
struct address_space *mapping = nf->nf_file->f_mapping;
int ret = filemap_fdatawrite_range(mapping, offset, end);
if (ret)
return ret;
filemap_fdatawait_range_keep_errors(mapping, offset, end);
return 0;
}
/*
* Commit all pending writes to stable storage.
*
@ -1153,10 +1166,11 @@ nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp,
if (err)
goto out;
if (EX_ISSYNC(fhp->fh_export)) {
int err2;
int err2 = nfsd_filemap_write_and_wait_range(nf, offset, end);
down_write(&nf->nf_rwsem);
err2 = vfs_fsync_range(nf->nf_file, offset, end, 0);
if (!err2)
err2 = vfs_fsync_range(nf->nf_file, offset, end, 0);
switch (err2) {
case 0:
nfsd_copy_boot_verifier(verf, net_generic(nf->nf_net,