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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 29/32] fscache: Implement "will_modify" parameter on fscache_use_cookie() From: David Howells To: Trond Myklebust , Anna Schumaker , Steve French , Alexander Viro , Matthew Wilcox Cc: Jeff Layton , Dave Wysochanski , dhowells@redhat.com, linux-cachefs@redhat.com, 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, 13 Jul 2020 17:36:08 +0100 Message-ID: <159465816816.1376674.16552237991218497564.stgit@warthog.procyon.org.uk> In-Reply-To: <159465784033.1376674.18106463693989811037.stgit@warthog.procyon.org.uk> References: <159465784033.1376674.18106463693989811037.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.22 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org Implement the "will_modify" parameter passed to fscache_use_cookie(). Setting this to true will henceforth cause the affected object to be marked as dirty on disk, subject to conflict resolution in the event that power failure or a crash occurs or the filesystem operates in disconnected mode. The dirty flag is removed when the fscache_object is discarded from memory. A cache hook is provided to prepare for writing - and this can be used to mark the object on disk. Signed-off-by: David Howells --- fs/cachefiles/interface.c | 65 +++++++++++++++++++++++++++++++++++++++++ fs/cachefiles/internal.h | 2 + fs/cachefiles/xattr.c | 21 +++++++++++++ fs/fscache/cookie.c | 17 +++++++++-- fs/fscache/internal.h | 1 + fs/fscache/obj.c | 28 +++++++++++++++--- include/linux/fscache-cache.h | 4 +++ 7 files changed, 129 insertions(+), 9 deletions(-) diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c index 76f3a89d3e6c..c626cc4248a7 100644 --- a/fs/cachefiles/interface.c +++ b/fs/cachefiles/interface.c @@ -210,14 +210,78 @@ static void cachefiles_update_object(struct fscache_object *_object) _leave(""); } +/* + * Shorten the backing object to discard any dirty data and free up + * any unused granules. + */ +static bool cachefiles_shorten_object(struct cachefiles_object *object, loff_t new_size) +{ + struct cachefiles_cache *cache; + struct inode *inode; + struct path path; + loff_t i_size; + + cache = container_of(object->fscache.cache, + struct cachefiles_cache, cache); + path.mnt = cache->mnt; + path.dentry = object->dentry; + + inode = d_inode(object->dentry); + trace_cachefiles_trunc(object, inode, i_size_read(inode), new_size); + if (vfs_truncate(&path, new_size) < 0) { + cachefiles_io_error_obj(object, "Trunc-to-size failed"); + cachefiles_remove_object_xattr(cache, object->dentry); + return false; + } + + new_size = round_up(new_size, CACHEFILES_DIO_BLOCK_SIZE); + i_size = i_size_read(inode); + if (i_size < new_size) { + trace_cachefiles_trunc(object, inode, i_size, new_size); + if (vfs_truncate(&path, new_size) < 0) { + cachefiles_io_error_obj(object, "Trunc-to-dio-size failed"); + cachefiles_remove_object_xattr(cache, object->dentry); + return false; + } + } + + return true; +} + +/* + * Trim excess stored data off of an object. + */ +static bool cachefiles_trim_object(struct cachefiles_object *object) +{ + loff_t object_size; + + _enter("{OBJ%x}", object->fscache.debug_id); + + object_size = object->fscache.cookie->object_size; + if (i_size_read(d_inode(object->dentry)) <= object_size) + return true; + + return cachefiles_shorten_object(object, object_size); +} + /* * Commit changes to the object as we drop it. */ static bool cachefiles_commit_object(struct cachefiles_object *object, struct cachefiles_cache *cache) { + bool update = false; + if (object->content_map_changed) cachefiles_save_content_map(object); + if (test_and_clear_bit(FSCACHE_OBJECT_LOCAL_WRITE, &object->fscache.flags)) + update = true; + if (test_and_clear_bit(FSCACHE_OBJECT_NEEDS_UPDATE, &object->fscache.flags)) + update = true; + if (update) { + if (cachefiles_trim_object(object)) + cachefiles_set_object_xattr(object); + } if (test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) return cachefiles_commit_tmpfile(cache, object); @@ -575,5 +639,6 @@ const struct fscache_cache_ops cachefiles_cache_ops = { .shape_request = cachefiles_shape_request, .read = cachefiles_read, .write = cachefiles_write, + .prepare_to_write = cachefiles_prepare_to_write, .display_object = cachefiles_display_object, }; diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index ba60fc9dda0a..bfe56eb53104 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -247,7 +247,7 @@ extern int cachefiles_set_object_xattr(struct cachefiles_object *object); extern int cachefiles_check_auxdata(struct cachefiles_object *object); extern int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, struct dentry *dentry); - +extern int cachefiles_prepare_to_write(struct fscache_object *object); /* * error handling diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c index 22c56ca2fd0b..456301b7abb0 100644 --- a/fs/cachefiles/xattr.c +++ b/fs/cachefiles/xattr.c @@ -124,6 +124,8 @@ int cachefiles_set_object_xattr(struct cachefiles_object *object) buf->zero_point = cpu_to_be64(object->fscache.cookie->zero_point); buf->type = object->fscache.cookie->type; buf->content = object->content_info; + if (test_bit(FSCACHE_OBJECT_LOCAL_WRITE, &object->fscache.flags)) + buf->content = CACHEFILES_CONTENT_DIRTY; if (len > 0) memcpy(buf->data, fscache_get_aux(object->fscache.cookie), len); @@ -184,10 +186,16 @@ int cachefiles_check_auxdata(struct cachefiles_object *object) why = cachefiles_coherency_check_aux; } else if (be64_to_cpu(buf->object_size) != object->fscache.cookie->object_size) { why = cachefiles_coherency_check_objsize; + } else if (buf->content == CACHEFILES_CONTENT_DIRTY) { + // TODO: Begin conflict resolution + pr_warn("Dirty object in cache\n"); + why = cachefiles_coherency_check_dirty; } else { object->fscache.cookie->zero_point = be64_to_cpu(buf->zero_point); object->content_info = buf->content; why = cachefiles_coherency_check_ok; + object->fscache.cookie->zero_point = be64_to_cpu(buf->zero_point); + object->content_info = buf->content; ret = 0; } @@ -219,3 +227,16 @@ int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, _leave(" = %d", ret); return ret; } + +/* + * Stick a marker on the cache object to indicate that it's dirty. + */ +int cachefiles_prepare_to_write(struct fscache_object *_object) +{ + struct cachefiles_object *object = + container_of(_object, struct cachefiles_object, fscache); + + _enter("c=%08x", object->fscache.cookie->debug_id); + + return cachefiles_set_object_xattr(object); +} diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c index fc93f4b69198..22cb8efe261f 100644 --- a/fs/fscache/cookie.c +++ b/fs/fscache/cookie.c @@ -342,6 +342,8 @@ EXPORT_SYMBOL(__fscache_acquire_cookie); void __fscache_use_cookie(struct fscache_cookie *cookie, bool will_modify) { enum fscache_cookie_stage stage; + struct fscache_object *object; + bool write_set; _enter("c=%08x", cookie->debug_id); @@ -360,7 +362,7 @@ void __fscache_use_cookie(struct fscache_cookie *cookie, bool will_modify) /* The lookup job holds its own active increment */ atomic_inc(&cookie->n_active); - fscache_dispatch(cookie, NULL, 0, fscache_lookup_object); + fscache_dispatch(cookie, NULL, will_modify, fscache_lookup_object); break; case FSCACHE_COOKIE_STAGE_INITIALISING: @@ -373,8 +375,17 @@ void __fscache_use_cookie(struct fscache_cookie *cookie, bool will_modify) case FSCACHE_COOKIE_STAGE_NO_DATA_YET: case FSCACHE_COOKIE_STAGE_ACTIVE: case FSCACHE_COOKIE_STAGE_INVALIDATING: - // TODO: Handle will_modify - spin_unlock(&cookie->lock); + if (will_modify) { + object = hlist_entry(cookie->backing_objects.first, + struct fscache_object, cookie_link); + write_set = test_and_set_bit(FSCACHE_OBJECT_LOCAL_WRITE, + &object->flags); + spin_unlock(&cookie->lock); + if (!write_set) + fscache_dispatch(cookie, object, 0, fscache_prepare_to_write); + } else { + spin_unlock(&cookie->lock); + } break; case FSCACHE_COOKIE_STAGE_DEAD: diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h index d9391d3974d1..120bb68f74b1 100644 --- a/fs/fscache/internal.h +++ b/fs/fscache/internal.h @@ -136,6 +136,7 @@ extern void fscache_lookup_object(struct fscache_cookie *, struct fscache_object extern void fscache_invalidate_object(struct fscache_cookie *, struct fscache_object *, int); extern void fscache_drop_object(struct fscache_cookie *, struct fscache_object *, bool); extern void fscache_discard_objects(struct fscache_cookie *, struct fscache_object *, int); +extern void fscache_prepare_to_write(struct fscache_cookie *, struct fscache_object *, int); /* * object-list.c diff --git a/fs/fscache/obj.c b/fs/fscache/obj.c index a7064a4cb486..139b59472628 100644 --- a/fs/fscache/obj.c +++ b/fs/fscache/obj.c @@ -117,7 +117,8 @@ static bool fscache_wrangle_object(struct fscache_cookie *cookie, * Create an object chain, making sure that the index chain is fully created. */ static struct fscache_object *fscache_lookup_object_chain(struct fscache_cookie *cookie, - struct fscache_cache *cache) + struct fscache_cache *cache, + bool will_modify) { struct fscache_object *object = NULL, *parent, *xobject; @@ -131,7 +132,7 @@ static struct fscache_object *fscache_lookup_object_chain(struct fscache_cookie spin_unlock(&cookie->lock); /* Recurse to look up/create the parent index. */ - parent = fscache_lookup_object_chain(cookie->parent, cache); + parent = fscache_lookup_object_chain(cookie->parent, cache, false); if (IS_ERR(parent)) goto error; @@ -146,6 +147,9 @@ static struct fscache_object *fscache_lookup_object_chain(struct fscache_cookie if (!object) goto error; + if (will_modify) + __set_bit(FSCACHE_OBJECT_LOCAL_WRITE, &object->flags); + xobject = fscache_attach_object(cookie, object); if (xobject != object) { fscache_do_put_object(object, fscache_obj_put_alloc_dup); @@ -203,7 +207,8 @@ static struct fscache_object *fscache_lookup_object_chain(struct fscache_cookie * - this must make sure the index chain is instantiated and instantiate the * object representation too */ -static void fscache_lookup_object_locked(struct fscache_cookie *cookie) +static void fscache_lookup_object_locked(struct fscache_cookie *cookie, + bool will_modify) { struct fscache_object *object; struct fscache_cache *cache; @@ -221,12 +226,16 @@ static void fscache_lookup_object_locked(struct fscache_cookie *cookie) _debug("cache %s", cache->tag->name); - object = fscache_lookup_object_chain(cookie, cache); + object = fscache_lookup_object_chain(cookie, cache, will_modify); if (!object) { _leave(" [fail]"); return; } + if (will_modify && + test_and_set_bit(FSCACHE_OBJECT_LOCAL_WRITE, &object->flags)) + fscache_prepare_to_write(cookie, object, 0); + fscache_do_put_object(object, fscache_obj_put); _leave(" [done]"); } @@ -235,7 +244,7 @@ void fscache_lookup_object(struct fscache_cookie *cookie, struct fscache_object *object, int param) { down_read(&fscache_addremove_sem); - fscache_lookup_object_locked(cookie); + fscache_lookup_object_locked(cookie, param); up_read(&fscache_addremove_sem); __fscache_unuse_cookie(cookie, NULL, NULL); } @@ -339,3 +348,12 @@ void fscache_discard_objects(struct fscache_cookie *cookie, up_read(&fscache_addremove_sem); _leave(""); } + +/* + * Prepare a cache object to be written to. + */ +void fscache_prepare_to_write(struct fscache_cookie *cookie, + struct fscache_object *object, int param) +{ + object->cache->ops->prepare_to_write(object); +} diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h index da85eb15b3c9..3625fd431d9f 100644 --- a/include/linux/fscache-cache.h +++ b/include/linux/fscache-cache.h @@ -154,6 +154,9 @@ struct fscache_cache_ops { struct fscache_io_request *req, struct iov_iter *iter); + /* Prepare to write to a live cache object */ + int (*prepare_to_write)(struct fscache_object *object); + /* Display object info in /proc/fs/fscache/objects */ int (*display_object)(struct seq_file *m, struct fscache_object *object); }; @@ -182,6 +185,7 @@ struct fscache_object { spinlock_t lock; /* state and operations lock */ unsigned long flags; +#define FSCACHE_OBJECT_LOCAL_WRITE 1 /* T if the object is being modified locally */ #define FSCACHE_OBJECT_NEEDS_INVAL 8 /* T if object needs invalidation */ #define FSCACHE_OBJECT_NEEDS_UPDATE 9 /* T if object attrs need writing to disk */