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 <[email protected]> --- fs/cachefiles/Makefile | 1 + fs/cachefiles/interface.c | 13 +++++++ fs/cachefiles/internal.h | 19 ++++++++++ fs/cachefiles/io.c | 85 +++++++++++++++++++++++++++++++++++++++++++++ fs/cachefiles/namei.c | 3 ++ 5 files changed, 120 insertions(+), 1 deletion(-) 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 3f6d2be690bc..dc8c875223bb 100644 --- a/fs/cachefiles/interface.c +++ b/fs/cachefiles/interface.c @@ -453,6 +453,18 @@ static unsigned int cachefiles_get_object_usage(const struct fscache_object *_ob return atomic_read(&object->usage); } +static const struct fscache_op_ops cachefiles_io_ops = { + .wait_for_operation = __fscache_wait_for_operation, + .end_operation = __fscache_end_operation, + .read = cachefiles_read, + .write = cachefiles_write, +}; + +static void cachefiles_begin_operation(struct fscache_op_resources *opr) +{ + opr->ops = &cachefiles_io_ops; +} + const struct fscache_cache_ops cachefiles_cache_ops = { .name = "cachefiles", .alloc_object = cachefiles_alloc_object, @@ -466,4 +478,5 @@ 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, + .begin_operation = cachefiles_begin_operation, }; diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index 16d15291a629..caa6dfbaf333 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -115,6 +115,22 @@ 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 int cachefiles_read(struct fscache_op_resources *opr, + loff_t start_pos, + struct iov_iter *iter, + bool seek_data, + fscache_io_terminated_t term_func, + void *term_func_priv); +extern int cachefiles_write(struct fscache_op_resources *opr, + loff_t start_pos, + struct iov_iter *iter, + fscache_io_terminated_t term_func, + void *term_func_priv); +extern bool cachefiles_open_object(struct cachefiles_object *obj); + /* * key.c */ @@ -216,7 +232,8 @@ do { \ \ ___cache = container_of((object)->fscache.cache, \ struct cachefiles_cache, cache); \ - cachefiles_io_error(___cache, FMT, ##__VA_ARGS__); \ + cachefiles_io_error(___cache, FMT " [o=%08x]", ##__VA_ARGS__, \ + object->fscache.debug_id); \ } while (0) diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c new file mode 100644 index 000000000000..f1d5976aa28c --- /dev/null +++ b/fs/cachefiles/io.c @@ -0,0 +1,85 @@ +// 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 ([email protected]) + */ + +#include <linux/mount.h> +#include <linux/slab.h> +#include <linux/file.h> +#include <linux/uio.h> +#include <linux/xattr.h> +#include "internal.h" +#include <trace/events/fscache.h> + +/* + * Initiate a read from the cache. + */ +int cachefiles_read(struct fscache_op_resources *opr, + loff_t start_pos, + struct iov_iter *iter, + bool seek_data, + fscache_io_terminated_t term_func, + void *term_func_priv) +{ + fscache_wait_for_operation(opr, FSCACHE_WANT_READ); + fscache_count_io_operation(opr->object->cookie); + if (term_func) + term_func(term_func_priv, -ENODATA); + return -ENODATA; +} + +/* + * Initiate a write to the cache. + */ +int cachefiles_write(struct fscache_op_resources *opr, + loff_t start_pos, + struct iov_iter *iter, + fscache_io_terminated_t term_func, + void *term_func_priv) +{ + fscache_wait_for_operation(opr, FSCACHE_WANT_WRITE); + fscache_count_io_operation(opr->object->cookie); + if (term_func) + term_func(term_func_priv, -ENOBUFS); + 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 0a7e2031efa2..4b515054d92e 100644 --- a/fs/cachefiles/namei.c +++ b/fs/cachefiles/namei.c @@ -490,6 +490,9 @@ 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)
