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Registered in England and Wales under Company Registration No. 3798903 Subject: [RFC PATCH 31/61] cachefiles: Implement new fscache I/O backend API From: David Howells To: Trond Myklebust , Anna Schumaker , Steve French , Jeff Layton Cc: dhowells@redhat.com, Matthew Wilcox , Alexander Viro , linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 04 May 2020 18:12:09 +0100 Message-ID: <158861232949.340223.21702873867667105.stgit@warthog.procyon.org.uk> In-Reply-To: <158861203563.340223.7585359869938129395.stgit@warthog.procyon.org.uk> References: <158861203563.340223.7585359869938129395.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.21 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Implement the new fscache I/O backend API in cachefiles. The cachefiles_object struct carries a non-accounted file to the cachefiles object (so that it doesn't cause ENFILE). Signed-off-by: David Howells --- fs/cachefiles/Makefile | 1 + fs/cachefiles/interface.c | 3 ++ fs/cachefiles/internal.h | 14 +++++++ fs/cachefiles/io.c | 88 +++++++++++++++++++++++++++++++++++++++++++++ fs/cachefiles/namei.c | 3 ++ 5 files changed, 109 insertions(+) create mode 100644 fs/cachefiles/io.c diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile index 3455d3646547..d894d317d6e7 100644 --- a/fs/cachefiles/Makefile +++ b/fs/cachefiles/Makefile @@ -7,6 +7,7 @@ cachefiles-y := \ bind.o \ daemon.o \ interface.o \ + io.o \ key.o \ main.o \ namei.o \ diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c index 47596b58c2da..747211363ae0 100644 --- a/fs/cachefiles/interface.c +++ b/fs/cachefiles/interface.c @@ -469,4 +469,7 @@ const struct fscache_cache_ops cachefiles_cache_ops = { .put_object = cachefiles_put_object, .get_object_usage = cachefiles_get_object_usage, .sync_cache = cachefiles_sync_cache, + .shape_extent = cachefiles_shape_extent, + .read = cachefiles_read, + .write = cachefiles_write, }; diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index 16d15291a629..9f9e33893b4f 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -115,6 +115,20 @@ extern const struct fscache_cache_ops cachefiles_cache_ops; extern struct fscache_object *cachefiles_grab_object(struct fscache_object *_object, enum fscache_obj_ref_trace why); +/* + * io.c + */ +extern unsigned int cachefiles_shape_extent(struct fscache_object *object, + struct fscache_extent *extent, + loff_t i_size, bool for_write); +extern int cachefiles_read(struct fscache_object *object, + struct fscache_io_request *req, + struct iov_iter *iter); +extern int cachefiles_write(struct fscache_object *object, + struct fscache_io_request *req, + struct iov_iter *iter); +extern bool cachefiles_open_object(struct cachefiles_object *obj); + /* * key.c */ diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c new file mode 100644 index 000000000000..d472e9d9173c --- /dev/null +++ b/fs/cachefiles/io.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Data I/O routines + * + * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include +#include +#include "internal.h" + +/* + * Determine the size of a data extent in a cache object. This must be written + * as a whole unit, but can be read piecemeal. + */ +unsigned int cachefiles_shape_extent(struct fscache_object *object, + struct fscache_extent *extent, + loff_t i_size, bool for_write) +{ + return 0; +} + +/* + * Initiate a read from the cache. + */ +int cachefiles_read(struct fscache_object *object, + struct fscache_io_request *req, + struct iov_iter *iter) +{ + req->error = -ENODATA; + if (req->io_done) + req->io_done(req); + return -ENODATA; +} + +/* + * Initiate a write to the cache. + */ +int cachefiles_write(struct fscache_object *object, + struct fscache_io_request *req, + struct iov_iter *iter) +{ + req->error = -ENOBUFS; + if (req->io_done) + req->io_done(req); + return -ENOBUFS; +} + +/* + * Open a cache object. + */ +bool cachefiles_open_object(struct cachefiles_object *object) +{ + struct cachefiles_cache *cache = + container_of(object->fscache.cache, struct cachefiles_cache, cache); + struct file *file; + struct path path; + + path.mnt = cache->mnt; + path.dentry = object->backer; + + file = open_with_fake_path(&path, + O_RDWR | O_LARGEFILE | O_DIRECT, + d_backing_inode(object->backer), + cache->cache_cred); + if (IS_ERR(file)) + goto error; + + if (!S_ISREG(file_inode(file)->i_mode)) + goto error_file; + + if (unlikely(!file->f_op->read_iter) || + unlikely(!file->f_op->write_iter)) { + pr_notice("Cache does not support read_iter and write_iter\n"); + goto error_file; + } + + object->backing_file = file; + return true; + +error_file: + fput(file); +error: + return false; +} diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c index ad7edd41ce27..c33b5ee65ac1 100644 --- a/fs/cachefiles/namei.c +++ b/fs/cachefiles/namei.c @@ -492,6 +492,9 @@ bool cachefiles_walk_to_object(struct cachefiles_object *parent, } else { BUG(); // TODO: open file in data-class subdir } + + if (!cachefiles_open_object(object)) + goto check_error; } if (object->new)