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-rw-r--r--fs/cachefiles/interface.c447
1 files changed, 447 insertions, 0 deletions
diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
new file mode 100644
index 0000000000..40052bdb33
--- /dev/null
+++ b/fs/cachefiles/interface.c
@@ -0,0 +1,447 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* FS-Cache interface to CacheFiles
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/slab.h>
+#include <linux/mount.h>
+#include <linux/xattr.h>
+#include <linux/file.h>
+#include <linux/falloc.h>
+#include <trace/events/fscache.h>
+#include "internal.h"
+
+static atomic_t cachefiles_object_debug_id;
+
+/*
+ * Allocate a cache object record.
+ */
+static
+struct cachefiles_object *cachefiles_alloc_object(struct fscache_cookie *cookie)
+{
+ struct fscache_volume *vcookie = cookie->volume;
+ struct cachefiles_volume *volume = vcookie->cache_priv;
+ struct cachefiles_object *object;
+
+ _enter("{%s},%x,", vcookie->key, cookie->debug_id);
+
+ object = kmem_cache_zalloc(cachefiles_object_jar, GFP_KERNEL);
+ if (!object)
+ return NULL;
+
+ refcount_set(&object->ref, 1);
+
+ spin_lock_init(&object->lock);
+ INIT_LIST_HEAD(&object->cache_link);
+ object->volume = volume;
+ object->debug_id = atomic_inc_return(&cachefiles_object_debug_id);
+ object->cookie = fscache_get_cookie(cookie, fscache_cookie_get_attach_object);
+
+ fscache_count_object(vcookie->cache);
+ trace_cachefiles_ref(object->debug_id, cookie->debug_id, 1,
+ cachefiles_obj_new);
+ return object;
+}
+
+/*
+ * Note that an object has been seen.
+ */
+void cachefiles_see_object(struct cachefiles_object *object,
+ enum cachefiles_obj_ref_trace why)
+{
+ trace_cachefiles_ref(object->debug_id, object->cookie->debug_id,
+ refcount_read(&object->ref), why);
+}
+
+/*
+ * Increment the usage count on an object;
+ */
+struct cachefiles_object *cachefiles_grab_object(struct cachefiles_object *object,
+ enum cachefiles_obj_ref_trace why)
+{
+ int r;
+
+ __refcount_inc(&object->ref, &r);
+ trace_cachefiles_ref(object->debug_id, object->cookie->debug_id, r, why);
+ return object;
+}
+
+/*
+ * dispose of a reference to an object
+ */
+void cachefiles_put_object(struct cachefiles_object *object,
+ enum cachefiles_obj_ref_trace why)
+{
+ unsigned int object_debug_id = object->debug_id;
+ unsigned int cookie_debug_id = object->cookie->debug_id;
+ struct fscache_cache *cache;
+ bool done;
+ int r;
+
+ done = __refcount_dec_and_test(&object->ref, &r);
+ trace_cachefiles_ref(object_debug_id, cookie_debug_id, r, why);
+ if (done) {
+ _debug("- kill object OBJ%x", object_debug_id);
+
+ ASSERTCMP(object->file, ==, NULL);
+
+ kfree(object->d_name);
+
+ cache = object->volume->cache->cache;
+ fscache_put_cookie(object->cookie, fscache_cookie_put_object);
+ object->cookie = NULL;
+ kmem_cache_free(cachefiles_object_jar, object);
+ fscache_uncount_object(cache);
+ }
+
+ _leave("");
+}
+
+/*
+ * Adjust the size of a cache file if necessary to match the DIO size. We keep
+ * the EOF marker a multiple of DIO blocks so that we don't fall back to doing
+ * non-DIO for a partial block straddling the EOF, but we also have to be
+ * careful of someone expanding the file and accidentally accreting the
+ * padding.
+ */
+static int cachefiles_adjust_size(struct cachefiles_object *object)
+{
+ struct iattr newattrs;
+ struct file *file = object->file;
+ uint64_t ni_size;
+ loff_t oi_size;
+ int ret;
+
+ ni_size = object->cookie->object_size;
+ ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE);
+
+ _enter("{OBJ%x},[%llu]",
+ object->debug_id, (unsigned long long) ni_size);
+
+ if (!file)
+ return -ENOBUFS;
+
+ oi_size = i_size_read(file_inode(file));
+ if (oi_size == ni_size)
+ return 0;
+
+ inode_lock(file_inode(file));
+
+ /* if there's an extension to a partial page at the end of the backing
+ * file, we need to discard the partial page so that we pick up new
+ * data after it */
+ if (oi_size & ~PAGE_MASK && ni_size > oi_size) {
+ _debug("discard tail %llx", oi_size);
+ newattrs.ia_valid = ATTR_SIZE;
+ newattrs.ia_size = oi_size & PAGE_MASK;
+ ret = cachefiles_inject_remove_error();
+ if (ret == 0)
+ ret = notify_change(&nop_mnt_idmap, file->f_path.dentry,
+ &newattrs, NULL);
+ if (ret < 0)
+ goto truncate_failed;
+ }
+
+ newattrs.ia_valid = ATTR_SIZE;
+ newattrs.ia_size = ni_size;
+ ret = cachefiles_inject_write_error();
+ if (ret == 0)
+ ret = notify_change(&nop_mnt_idmap, file->f_path.dentry,
+ &newattrs, NULL);
+
+truncate_failed:
+ inode_unlock(file_inode(file));
+
+ if (ret < 0)
+ trace_cachefiles_io_error(NULL, file_inode(file), ret,
+ cachefiles_trace_notify_change_error);
+ if (ret == -EIO) {
+ cachefiles_io_error_obj(object, "Size set failed");
+ ret = -ENOBUFS;
+ }
+
+ _leave(" = %d", ret);
+ return ret;
+}
+
+/*
+ * Attempt to look up the nominated node in this cache
+ */
+static bool cachefiles_lookup_cookie(struct fscache_cookie *cookie)
+{
+ struct cachefiles_object *object;
+ struct cachefiles_cache *cache = cookie->volume->cache->cache_priv;
+ const struct cred *saved_cred;
+ bool success;
+
+ object = cachefiles_alloc_object(cookie);
+ if (!object)
+ goto fail;
+
+ _enter("{OBJ%x}", object->debug_id);
+
+ if (!cachefiles_cook_key(object))
+ goto fail_put;
+
+ cookie->cache_priv = object;
+
+ cachefiles_begin_secure(cache, &saved_cred);
+
+ success = cachefiles_look_up_object(object);
+ if (!success)
+ goto fail_withdraw;
+
+ cachefiles_see_object(object, cachefiles_obj_see_lookup_cookie);
+
+ spin_lock(&cache->object_list_lock);
+ list_add(&object->cache_link, &cache->object_list);
+ spin_unlock(&cache->object_list_lock);
+ cachefiles_adjust_size(object);
+
+ cachefiles_end_secure(cache, saved_cred);
+ _leave(" = t");
+ return true;
+
+fail_withdraw:
+ cachefiles_end_secure(cache, saved_cred);
+ cachefiles_see_object(object, cachefiles_obj_see_lookup_failed);
+ fscache_caching_failed(cookie);
+ _debug("failed c=%08x o=%08x", cookie->debug_id, object->debug_id);
+ /* The caller holds an access count on the cookie, so we need them to
+ * drop it before we can withdraw the object.
+ */
+ return false;
+
+fail_put:
+ cachefiles_put_object(object, cachefiles_obj_put_alloc_fail);
+fail:
+ return false;
+}
+
+/*
+ * Shorten the backing object to discard any dirty data and free up
+ * any unused granules.
+ */
+static bool cachefiles_shorten_object(struct cachefiles_object *object,
+ struct file *file, loff_t new_size)
+{
+ struct cachefiles_cache *cache = object->volume->cache;
+ struct inode *inode = file_inode(file);
+ loff_t i_size, dio_size;
+ int ret;
+
+ dio_size = round_up(new_size, CACHEFILES_DIO_BLOCK_SIZE);
+ i_size = i_size_read(inode);
+
+ trace_cachefiles_trunc(object, inode, i_size, dio_size,
+ cachefiles_trunc_shrink);
+ ret = cachefiles_inject_remove_error();
+ if (ret == 0)
+ ret = vfs_truncate(&file->f_path, dio_size);
+ if (ret < 0) {
+ trace_cachefiles_io_error(object, file_inode(file), ret,
+ cachefiles_trace_trunc_error);
+ cachefiles_io_error_obj(object, "Trunc-to-size failed %d", ret);
+ cachefiles_remove_object_xattr(cache, object, file->f_path.dentry);
+ return false;
+ }
+
+ if (new_size < dio_size) {
+ trace_cachefiles_trunc(object, inode, dio_size, new_size,
+ cachefiles_trunc_dio_adjust);
+ ret = cachefiles_inject_write_error();
+ if (ret == 0)
+ ret = vfs_fallocate(file, FALLOC_FL_ZERO_RANGE,
+ new_size, dio_size - new_size);
+ if (ret < 0) {
+ trace_cachefiles_io_error(object, file_inode(file), ret,
+ cachefiles_trace_fallocate_error);
+ cachefiles_io_error_obj(object, "Trunc-to-dio-size failed %d", ret);
+ cachefiles_remove_object_xattr(cache, object, file->f_path.dentry);
+ return false;
+ }
+ }
+
+ return true;
+}
+
+/*
+ * Resize the backing object.
+ */
+static void cachefiles_resize_cookie(struct netfs_cache_resources *cres,
+ loff_t new_size)
+{
+ struct cachefiles_object *object = cachefiles_cres_object(cres);
+ struct cachefiles_cache *cache = object->volume->cache;
+ struct fscache_cookie *cookie = object->cookie;
+ const struct cred *saved_cred;
+ struct file *file = cachefiles_cres_file(cres);
+ loff_t old_size = cookie->object_size;
+
+ _enter("%llu->%llu", old_size, new_size);
+
+ if (new_size < old_size) {
+ cachefiles_begin_secure(cache, &saved_cred);
+ cachefiles_shorten_object(object, file, new_size);
+ cachefiles_end_secure(cache, saved_cred);
+ object->cookie->object_size = new_size;
+ return;
+ }
+
+ /* The file is being expanded. We don't need to do anything
+ * particularly. cookie->initial_size doesn't change and so the point
+ * at which we have to download before doesn't change.
+ */
+ cookie->object_size = new_size;
+}
+
+/*
+ * Commit changes to the object as we drop it.
+ */
+static void cachefiles_commit_object(struct cachefiles_object *object,
+ struct cachefiles_cache *cache)
+{
+ bool update = false;
+
+ if (test_and_clear_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags))
+ update = true;
+ if (test_and_clear_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags))
+ update = true;
+ if (update)
+ cachefiles_set_object_xattr(object);
+
+ if (test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags))
+ cachefiles_commit_tmpfile(cache, object);
+}
+
+/*
+ * Finalise and object and close the VFS structs that we have.
+ */
+static void cachefiles_clean_up_object(struct cachefiles_object *object,
+ struct cachefiles_cache *cache)
+{
+ if (test_bit(FSCACHE_COOKIE_RETIRED, &object->cookie->flags)) {
+ if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
+ cachefiles_see_object(object, cachefiles_obj_see_clean_delete);
+ _debug("- inval object OBJ%x", object->debug_id);
+ cachefiles_delete_object(object, FSCACHE_OBJECT_WAS_RETIRED);
+ } else {
+ cachefiles_see_object(object, cachefiles_obj_see_clean_drop_tmp);
+ _debug("- inval object OBJ%x tmpfile", object->debug_id);
+ }
+ } else {
+ cachefiles_see_object(object, cachefiles_obj_see_clean_commit);
+ cachefiles_commit_object(object, cache);
+ }
+
+ cachefiles_unmark_inode_in_use(object, object->file);
+ if (object->file) {
+ fput(object->file);
+ object->file = NULL;
+ }
+}
+
+/*
+ * Withdraw caching for a cookie.
+ */
+static void cachefiles_withdraw_cookie(struct fscache_cookie *cookie)
+{
+ struct cachefiles_object *object = cookie->cache_priv;
+ struct cachefiles_cache *cache = object->volume->cache;
+ const struct cred *saved_cred;
+
+ _enter("o=%x", object->debug_id);
+ cachefiles_see_object(object, cachefiles_obj_see_withdraw_cookie);
+
+ if (!list_empty(&object->cache_link)) {
+ spin_lock(&cache->object_list_lock);
+ cachefiles_see_object(object, cachefiles_obj_see_withdrawal);
+ list_del_init(&object->cache_link);
+ spin_unlock(&cache->object_list_lock);
+ }
+
+ cachefiles_ondemand_clean_object(object);
+
+ if (object->file) {
+ cachefiles_begin_secure(cache, &saved_cred);
+ cachefiles_clean_up_object(object, cache);
+ cachefiles_end_secure(cache, saved_cred);
+ }
+
+ cookie->cache_priv = NULL;
+ cachefiles_put_object(object, cachefiles_obj_put_detach);
+}
+
+/*
+ * Invalidate the storage associated with a cookie.
+ */
+static bool cachefiles_invalidate_cookie(struct fscache_cookie *cookie)
+{
+ struct cachefiles_object *object = cookie->cache_priv;
+ struct file *new_file, *old_file;
+ bool old_tmpfile;
+
+ _enter("o=%x,[%llu]", object->debug_id, object->cookie->object_size);
+
+ old_tmpfile = test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags);
+
+ if (!object->file) {
+ fscache_resume_after_invalidation(cookie);
+ _leave(" = t [light]");
+ return true;
+ }
+
+ new_file = cachefiles_create_tmpfile(object);
+ if (IS_ERR(new_file))
+ goto failed;
+
+ /* Substitute the VFS target */
+ _debug("sub");
+ spin_lock(&object->lock);
+
+ old_file = object->file;
+ object->file = new_file;
+ object->content_info = CACHEFILES_CONTENT_NO_DATA;
+ set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags);
+ set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags);
+
+ spin_unlock(&object->lock);
+ _debug("subbed");
+
+ /* Allow I/O to take place again */
+ fscache_resume_after_invalidation(cookie);
+
+ if (old_file) {
+ if (!old_tmpfile) {
+ struct cachefiles_volume *volume = object->volume;
+ struct dentry *fan = volume->fanout[(u8)cookie->key_hash];
+
+ inode_lock_nested(d_inode(fan), I_MUTEX_PARENT);
+ cachefiles_bury_object(volume->cache, object, fan,
+ old_file->f_path.dentry,
+ FSCACHE_OBJECT_INVALIDATED);
+ }
+ fput(old_file);
+ }
+
+ _leave(" = t");
+ return true;
+
+failed:
+ _leave(" = f");
+ return false;
+}
+
+const struct fscache_cache_ops cachefiles_cache_ops = {
+ .name = "cachefiles",
+ .acquire_volume = cachefiles_acquire_volume,
+ .free_volume = cachefiles_free_volume,
+ .lookup_cookie = cachefiles_lookup_cookie,
+ .withdraw_cookie = cachefiles_withdraw_cookie,
+ .invalidate_cookie = cachefiles_invalidate_cookie,
+ .begin_operation = cachefiles_begin_operation,
+ .resize_cookie = cachefiles_resize_cookie,
+ .prepare_to_write = cachefiles_prepare_to_write,
+};