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Tue, 04 Aug 2026 06:06:04 -0400 X-MC-Unique: sIuaNUnoPAyAEPB2D6aUkA-1 X-Mimecast-MFC-AGG-ID: sIuaNUnoPAyAEPB2D6aUkA_1785837961 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5AC731955DAF; Tue, 4 Aug 2026 10:06:01 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.44.32.44]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 759C7195608E; Tue, 4 Aug 2026 10:05:55 +0000 (UTC) From: David Howells To: Christian Brauner , Matthew Wilcox , Christoph Hellwig Cc: David Howells , Paulo Alcantara , Jens Axboe , Leon Romanovsky , Steve French , ChenXiaoSong , Marc Dionne , Stefan Metzmacher , Eric Van Hensbergen , Dominique Martinet , Ilya Dryomov , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v8 25/25] cachefiles: Preset the state xattr when creating a new file Date: Tue, 4 Aug 2026 11:02:20 +0100 Message-ID: <20260804100224.2748935-26-dhowells@redhat.com> In-Reply-To: <20260804100224.2748935-1-dhowells@redhat.com> References: <20260804100224.2748935-1-dhowells@redhat.com> X-Mailing-List: linux-erofs@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-MFC-PROC-ID: HZva4kWHZzp-G4bVqE2f2ujoMXaAzhCFPGBR6nH1DZs_1785837961 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true With a really small cache, cachefiles is likely to see a lot of writes hitting ENOSPC - and this can include setxattr that sets the state xattr on a cachefile - but we don't really want to successfully fill a cache file only to have to scrap it because we can't set the xattr. Instead, preset the xattr when we create the tmpfile we're going to use, and scrap the file at that point if we get ENOSPC. Only if setxattr succeeds do we allow data to be written to the file. Note that there is a potential performance loss in that writes to the cache have to be delayed until this is completed - but we do the tmpfile/setxattr in parallel, starting when the file is opened and only have to wait once writeback occurs. Further, a new tracepoint, cachefiles_no_space, has been added to log ENOSPC events, along with a couple of subreq traces to log failure detection in netfslib. Signed-off-by: David Howells cc: Marc Dionne cc: Paulo Alcantara cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org --- fs/cachefiles/internal.h | 1 + fs/cachefiles/io.c | 23 ++++++++---- fs/cachefiles/namei.c | 15 ++++++-- fs/cachefiles/xattr.c | 60 ++++++++++++++++++++++++++++++- include/trace/events/cachefiles.h | 28 ++++++++++++++- include/trace/events/netfs.h | 2 ++ 6 files changed, 119 insertions(+), 10 deletions(-) diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index 99d5f9077a31..71832fdb3770 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -287,6 +287,7 @@ void cachefiles_withdraw_volume(struct cachefiles_volume *volume); /* * xattr.c */ +int cachefiles_preset_object_xattr(struct cachefiles_object *object, struct file *file); extern int cachefiles_set_object_xattr(struct cachefiles_object *object); extern int cachefiles_check_auxdata(struct cachefiles_object *object, struct file *file); diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c index b06d0fbcc81e..e8722b9bf183 100644 --- a/fs/cachefiles/io.c +++ b/fs/cachefiles/io.c @@ -672,10 +672,14 @@ int __cachefiles_prepare_write(struct cachefiles_object *object, * space, we need to see if it's fully allocated. If it's not, we may * want to cull it. */ - if (cachefiles_has_space(cache, 0, *_len / cache->bsize, - cachefiles_has_space_check) == 0) + ret = cachefiles_has_space(cache, 0, *_len / cache->bsize, + cachefiles_has_space_check); + if (ret == 0) return 0; /* Enough space to simply overwrite the whole block */ + if (ret == -ENOBUFS) + trace_cachefiles_no_space(object, cachefiles_trace_write_nospace); + pos = cachefiles_inject_read_error(); if (pos == 0) pos = vfs_llseek(file, start, SEEK_HOLE); @@ -704,8 +708,11 @@ int __cachefiles_prepare_write(struct cachefiles_object *object, return ret; check_space: - return cachefiles_has_space(cache, 0, *_len / cache->bsize, - cachefiles_has_space_for_write); + ret = cachefiles_has_space(cache, 0, *_len / cache->bsize, + cachefiles_has_space_for_write); + if (ret == -ENOBUFS) + trace_cachefiles_no_space(object, cachefiles_trace_write_nospace); + return ret; } static int cachefiles_prepare_write_old(struct netfs_cache_resources *cres, @@ -757,10 +764,14 @@ static int cachefiles_issue_write(struct netfs_io_subrequest *subreq) wreq->debug_id, subreq->debug_index, start, start + len - 1); if (!cachefiles_cres_file(cres)) { - if (!fscache_wait_for_operation(cres, FSCACHE_WANT_WRITE)) + if (!fscache_wait_for_operation(cres, FSCACHE_WANT_WRITE)) { + trace_netfs_sreq(subreq, netfs_sreq_trace_cache_waitfail); return -EINVAL; - if (!cachefiles_cres_file(cres)) + } + if (!cachefiles_cres_file(cres)) { + trace_netfs_sreq(subreq, netfs_sreq_trace_cache_nofile); return -EINVAL; + } } ret = netfs_prepare_write_buffer(subreq, BIO_MAX_VECS); diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c index a30df0f91e5e..ef656a319ede 100644 --- a/fs/cachefiles/namei.c +++ b/fs/cachefiles/namei.c @@ -117,8 +117,11 @@ struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache, if (d_is_negative(subdir)) { ret = cachefiles_has_space(cache, 1, 0, cachefiles_has_space_for_create); - if (ret < 0) + if (ret < 0) { + if (ret == -ENOBUFS) + trace_cachefiles_no_space(NULL, cachefiles_trace_mkdir_nospace); goto mkdir_error; + } _debug("attempt mkdir"); @@ -447,6 +450,11 @@ struct file *cachefiles_create_tmpfile(struct cachefiles_object *object) pr_notice("Cache does not support read_iter and write_iter\n"); goto err_unuse; } + + /* Preallocate space for the xattr. */ + ret = cachefiles_preset_object_xattr(object, file); + if (ret < 0) + goto err_unuse; out: cachefiles_end_secure(cache, saved_cred); object->content_info = CACHEFILES_CONTENT_ALL; @@ -470,8 +478,11 @@ static bool cachefiles_create_file(struct cachefiles_object *object) ret = cachefiles_has_space(object->volume->cache, 1, 0, cachefiles_has_space_for_create); - if (ret < 0) + if (ret < 0) { + if (ret == -ENOBUFS) + trace_cachefiles_no_space(object, cachefiles_trace_create_nospace); return false; + } file = cachefiles_create_tmpfile(object); if (IS_ERR(file)) diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c index 25f2a906f984..2a7cc514f1a5 100644 --- a/fs/cachefiles/xattr.c +++ b/fs/cachefiles/xattr.c @@ -33,6 +33,58 @@ struct cachefiles_vol_xattr { __u8 data[]; /* netfs volume coherency data */ } __packed; +/* + * Preset the state xattr on a cache file to allocate space for it. + */ +int cachefiles_preset_object_xattr(struct cachefiles_object *object, struct file *file) +{ + struct cachefiles_xattr *buf; + struct dentry *dentry = file->f_path.dentry; + unsigned int len = object->cookie->aux_len; + int ret; + + buf = kzalloc(sizeof(struct cachefiles_xattr) + len, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + buf->type = CACHEFILES_COOKIE_TYPE_DATA; + buf->content = CACHEFILES_CONTENT_DIRTY; + + ret = cachefiles_inject_write_error(); + if (ret == 0) { + ret = mnt_want_write_file(file); + if (ret == 0) { + ret = vfs_setxattr(&nop_mnt_idmap, dentry, + cachefiles_xattr_cache, buf, + sizeof(struct cachefiles_xattr) + len, 0); + mnt_drop_write_file(file); + } + } + if (ret < 0) { + trace_cachefiles_vfs_error(object, file_inode(file), ret, + cachefiles_trace_setxattr_error); + trace_cachefiles_coherency(object, file_inode(file)->i_ino, + object->object_size, + be64_to_cpup((__be64 *)buf->data), + buf->content, + cachefiles_coherency_set_fail); + switch (ret) { + case -ENOMEM: + case -ENOSPC: + break; + default: + cachefiles_io_error_obj( + object, + "Failed to set xattr with error %d", ret); + break; + } + } + + kfree(buf); + _leave(" = %d", ret); + return ret; +} + /* * set the state xattr on a cache file */ @@ -81,10 +133,16 @@ int cachefiles_set_object_xattr(struct cachefiles_object *object) be64_to_cpup((__be64 *)buf->data), buf->content, cachefiles_coherency_set_fail); - if (ret != -ENOMEM) + switch (ret) { + case -ENOMEM: + break; + case -ENOSPC: + default: cachefiles_io_error_obj( object, "Failed to set xattr with error %d", ret); + break; + } } else { trace_cachefiles_coherency(object, file_inode(file)->i_ino, object->object_size, diff --git a/include/trace/events/cachefiles.h b/include/trace/events/cachefiles.h index eccdb5abeedc..c7b5b8587cca 100644 --- a/include/trace/events/cachefiles.h +++ b/include/trace/events/cachefiles.h @@ -85,11 +85,13 @@ enum cachefiles_prepare_read_trace { enum cachefiles_error_trace { cachefiles_trace_alignment_error, + cachefiles_trace_create_nospace, cachefiles_trace_fallocate_error, cachefiles_trace_getxattr_error, cachefiles_trace_link_error, cachefiles_trace_lookup_error, cachefiles_trace_mkdir_error, + cachefiles_trace_mkdir_nospace, cachefiles_trace_notify_change_error, cachefiles_trace_open_error, cachefiles_trace_read_error, @@ -102,6 +104,7 @@ enum cachefiles_error_trace { cachefiles_trace_trunc_error, cachefiles_trace_unlink_error, cachefiles_trace_write_error, + cachefiles_trace_write_nospace, }; #endif @@ -171,11 +174,13 @@ enum cachefiles_error_trace { #define cachefiles_error_traces \ EM(cachefiles_trace_alignment_error, "align") \ + EM(cachefiles_trace_create_nospace, "create-nospace") \ EM(cachefiles_trace_fallocate_error, "fallocate") \ EM(cachefiles_trace_getxattr_error, "getxattr") \ EM(cachefiles_trace_link_error, "link") \ EM(cachefiles_trace_lookup_error, "lookup") \ EM(cachefiles_trace_mkdir_error, "mkdir") \ + EM(cachefiles_trace_mkdir_nospace, "mkdir-nospace") \ EM(cachefiles_trace_notify_change_error, "notify_change") \ EM(cachefiles_trace_open_error, "open") \ EM(cachefiles_trace_read_error, "read") \ @@ -187,7 +192,8 @@ enum cachefiles_error_trace { EM(cachefiles_trace_tmpfile_error, "tmpfile") \ EM(cachefiles_trace_trunc_error, "trunc") \ EM(cachefiles_trace_unlink_error, "unlink") \ - E_(cachefiles_trace_write_error, "write") + EM(cachefiles_trace_write_error, "write") \ + E_(cachefiles_trace_write_nospace, "write-nospace") /* @@ -692,6 +698,26 @@ TRACE_EVENT(cachefiles_io_error, __entry->error) ); +TRACE_EVENT(cachefiles_no_space, + TP_PROTO(struct cachefiles_object *obj, enum cachefiles_error_trace trace), + + TP_ARGS(obj, trace), + + TP_STRUCT__entry( + __field(unsigned int, obj) + __field(enum cachefiles_error_trace, trace) + ), + + TP_fast_assign( + __entry->obj = obj ? obj->debug_id : 0; + __entry->trace = trace; + ), + + TP_printk("o=%08x %s", + __entry->obj, + __print_symbolic(__entry->trace, cachefiles_error_traces)) + ); + #endif /* _TRACE_CACHEFILES_H */ /* This part must be outside protection */ diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h index e6bbf2a09d92..45c1924c0b2f 100644 --- a/include/trace/events/netfs.h +++ b/include/trace/events/netfs.h @@ -101,8 +101,10 @@ EM(netfs_sreq_trace_abandoned, "ABNDN") \ EM(netfs_sreq_trace_add_donations, "+DON ") \ EM(netfs_sreq_trace_added, "ADD ") \ + EM(netfs_sreq_trace_cache_nofile, "CA-!F") \ EM(netfs_sreq_trace_cache_nowrite, "CA-NW") \ EM(netfs_sreq_trace_cache_prepare, "CA-PR") \ + EM(netfs_sreq_trace_cache_waitfail, "CA-!W") \ EM(netfs_sreq_trace_cache_write, "CA-WR") \ EM(netfs_sreq_trace_cancel, "CANCL") \ EM(netfs_sreq_trace_clear, "CLEAR") \