diff options
| -rw-r--r-- | fs/nfsd/debugfs.c | 2 | ||||
| -rw-r--r-- | fs/nfsd/nfsd.h | 1 | ||||
| -rw-r--r-- | fs/nfsd/trace.h | 1 | ||||
| -rw-r--r-- | fs/nfsd/vfs.c | 83 |
4 files changed, 87 insertions, 0 deletions
diff --git a/fs/nfsd/debugfs.c b/fs/nfsd/debugfs.c index ed2b9e066206..00eb1ecef6ac 100644 --- a/fs/nfsd/debugfs.c +++ b/fs/nfsd/debugfs.c @@ -44,6 +44,7 @@ DEFINE_DEBUGFS_ATTRIBUTE(nfsd_dsr_fops, nfsd_dsr_get, nfsd_dsr_set, "%llu\n"); * Contents: * %0: NFS READ will use buffered IO * %1: NFS READ will use dontcache (buffered IO w/ dropbehind) + * %2: NFS READ will use direct IO * * This setting takes immediate effect for all NFS versions, * all exports, and in all NFSD net namespaces. @@ -64,6 +65,7 @@ static int nfsd_io_cache_read_set(void *data, u64 val) nfsd_io_cache_read = NFSD_IO_BUFFERED; break; case NFSD_IO_DONTCACHE: + case NFSD_IO_DIRECT: /* * Must disable splice_read when enabling * NFSD_IO_DONTCACHE. diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h index 4b7296881f31..e4263326ca4a 100644 --- a/fs/nfsd/nfsd.h +++ b/fs/nfsd/nfsd.h @@ -160,6 +160,7 @@ enum { /* Any new NFSD_IO enum value must be added at the end */ NFSD_IO_BUFFERED, NFSD_IO_DONTCACHE, + NFSD_IO_DIRECT, }; extern u64 nfsd_io_cache_read __read_mostly; diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h index 6e2c8e2aab10..bfd41236aff2 100644 --- a/fs/nfsd/trace.h +++ b/fs/nfsd/trace.h @@ -464,6 +464,7 @@ DEFINE_EVENT(nfsd_io_class, nfsd_##name, \ DEFINE_NFSD_IO_EVENT(read_start); DEFINE_NFSD_IO_EVENT(read_splice); DEFINE_NFSD_IO_EVENT(read_vector); +DEFINE_NFSD_IO_EVENT(read_direct); DEFINE_NFSD_IO_EVENT(read_io_done); DEFINE_NFSD_IO_EVENT(read_done); DEFINE_NFSD_IO_EVENT(write_start); diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 406fe62de219..f537a7b4ee01 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1074,6 +1074,83 @@ __be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp, return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err); } +/* + * The byte range of the client's READ request is expanded on both ends + * until it meets the underlying file system's direct I/O alignment + * requirements. After the internal read is complete, the byte range of + * the NFS READ payload is reduced to the byte range that was originally + * requested. + * + * Note that a direct read can be done only when the xdr_buf containing + * the NFS READ reply does not already have contents in its .pages array. + * This is due to potentially restrictive alignment requirements on the + * read buffer. When .page_len and @base are zero, the .pages array is + * guaranteed to be page-aligned. + */ +static noinline_for_stack __be32 +nfsd_direct_read(struct svc_rqst *rqstp, struct svc_fh *fhp, + struct nfsd_file *nf, loff_t offset, unsigned long *count, + u32 *eof) +{ + u64 dio_start, dio_end; + unsigned long v, total; + struct iov_iter iter; + struct kiocb kiocb; + ssize_t host_err; + size_t len; + + init_sync_kiocb(&kiocb, nf->nf_file); + kiocb.ki_flags |= IOCB_DIRECT; + + /* Read a properly-aligned region of bytes into rq_bvec */ + dio_start = round_down(offset, nf->nf_dio_read_offset_align); + dio_end = round_up((u64)offset + *count, nf->nf_dio_read_offset_align); + + kiocb.ki_pos = dio_start; + + v = 0; + total = dio_end - dio_start; + while (total && v < rqstp->rq_maxpages && + rqstp->rq_next_page < rqstp->rq_page_end) { + len = min_t(size_t, total, PAGE_SIZE); + bvec_set_page(&rqstp->rq_bvec[v], *rqstp->rq_next_page, + len, 0); + + total -= len; + ++rqstp->rq_next_page; + ++v; + } + + trace_nfsd_read_direct(rqstp, fhp, offset, *count - total); + iov_iter_bvec(&iter, ITER_DEST, rqstp->rq_bvec, v, + dio_end - dio_start - total); + + host_err = vfs_iocb_iter_read(nf->nf_file, &kiocb, &iter); + if (host_err >= 0) { + unsigned int pad = offset - dio_start; + + /* The returned payload starts after the pad */ + rqstp->rq_res.page_base = pad; + + /* Compute the count of bytes to be returned */ + if (host_err > pad + *count) + host_err = *count; + else if (host_err > pad) + host_err -= pad; + else + host_err = 0; + } else if (unlikely(host_err == -EINVAL)) { + struct inode *inode = d_inode(fhp->fh_dentry); + + pr_info_ratelimited("nfsd: Direct I/O alignment failure on %s/%ld\n", + inode->i_sb->s_id, inode->i_ino); + host_err = -ESERVERFAULT; + } + + return nfsd_finish_read(rqstp, fhp, nf->nf_file, offset, count, + eof, host_err); +} + /** * nfsd_iter_read - Perform a VFS read using an iterator * @rqstp: RPC transaction context @@ -1106,6 +1183,12 @@ __be32 nfsd_iter_read(struct svc_rqst *rqstp, struct svc_fh *fhp, switch (nfsd_io_cache_read) { case NFSD_IO_BUFFERED: break; + case NFSD_IO_DIRECT: + /* When dio_read_offset_align is zero, dio is not supported */ + if (nf->nf_dio_read_offset_align && !rqstp->rq_res.page_len) + return nfsd_direct_read(rqstp, fhp, nf, offset, + count, eof); + fallthrough; case NFSD_IO_DONTCACHE: if (file->f_op->fop_flags & FOP_DONTCACHE) kiocb.ki_flags = IOCB_DONTCACHE; |