diff options
Diffstat (limited to 'fs/cachefiles/interface.c')
| -rw-r--r-- | fs/cachefiles/interface.c | 447 |
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, +}; |