From: HereThereBeDragons Date: Fri, 30 Jun 2023 12:57:06 +0000 (+0200) Subject: Make expire only function fail if no kernel support (#789) X-Git-Tag: fuse-3.16.1~11 X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=51bc827df873d9ff4069b83796cd32fcb6bd659e;p=qemu-gpiodev%2Flibfuse.git Make expire only function fail if no kernel support (#789) --- diff --git a/example/notify_inval_entry.c b/example/notify_inval_entry.c index 8af31bc..ea3d43f 100644 --- a/example/notify_inval_entry.c +++ b/example/notify_inval_entry.c @@ -85,6 +85,7 @@ #include #include #include +#include #include #include #include @@ -93,6 +94,7 @@ static char file_name[MAX_STR_LEN]; static fuse_ino_t file_ino = 2; static int lookup_cnt = 0; +static pthread_t main_thread; /* Command line parsing */ struct options { @@ -253,14 +255,32 @@ static void* update_fs_loop(void *data) { struct fuse_session *se = (struct fuse_session*) data; char *old_name; - while(1) { + + while(!fuse_session_exited(se)) { old_name = strdup(file_name); update_fs(); + if (!options.no_notify && lookup_cnt) { - if(options.only_expire) { - assert(fuse_lowlevel_notify_expire_entry - (se, FUSE_ROOT_ID, old_name, strlen(old_name), FUSE_LL_EXPIRE_ONLY) == 0); - } else { + if(options.only_expire) { // expire entry + int ret = fuse_lowlevel_notify_expire_entry + (se, FUSE_ROOT_ID, old_name, strlen(old_name)); + + // no kernel support + if (ret == -ENOSYS) { + printf("fuse_lowlevel_notify_expire_entry not supported by kernel\n"); + printf("Exiting...\n"); + + fuse_session_exit(se); + // Make sure to exit now, rather than on next request from userspace + pthread_kill(main_thread, SIGPIPE); + + break; + } + // 1) ret == 0: successful expire of an existing entry + // 2) ret == -ENOENT: kernel has already expired the entry / + // entry does not exist anymore in the kernel + assert(ret == 0 || ret == -ENOENT); + } else { // invalidate entry assert(fuse_lowlevel_notify_inval_entry (se, FUSE_ROOT_ID, old_name, strlen(old_name)) == 0); } @@ -312,7 +332,7 @@ int main(int argc, char *argv[]) { update_fs(); se = fuse_session_new(&args, &tfs_oper, - sizeof(tfs_oper), NULL); + sizeof(tfs_oper), &se); if (se == NULL) goto err_out1; @@ -324,6 +344,11 @@ int main(int argc, char *argv[]) { fuse_daemonize(opts.foreground); + // Needed to ensure that the main thread continues/restarts processing as soon + // as the fuse session ends (immediately after calling fuse_session_exit() ) + // and not only on the next request from userspace + main_thread = pthread_self(); + /* Start thread to update file contents */ ret = pthread_create(&updater, NULL, update_fs_loop, (void *)se); if (ret != 0) { @@ -333,9 +358,9 @@ int main(int argc, char *argv[]) { } /* Block until ctrl+c or fusermount -u */ - if (opts.singlethread) + if (opts.singlethread) { ret = fuse_session_loop(se); - else { + } else { config.clone_fd = opts.clone_fd; config.max_idle_threads = opts.max_idle_threads; ret = fuse_session_loop_mt(se, &config); diff --git a/include/fuse_common.h b/include/fuse_common.h index 3a1e1f8..837df5a 100644 --- a/include/fuse_common.h +++ b/include/fuse_common.h @@ -418,7 +418,7 @@ struct fuse_loop_config_v1 { #define FUSE_CAP_EXPLICIT_INVAL_DATA (1 << 25) /** - * Indicates support that dentries can be expired or invalidated. + * Indicates support that dentries can be expired. * * Expiring dentries, instead of invalidating them, makes a difference for * overmounted dentries, where plain invalidation would detach all submounts diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h index b42447e..3ac97eb 100644 --- a/include/fuse_lowlevel.h +++ b/include/fuse_lowlevel.h @@ -139,11 +139,12 @@ struct fuse_custom_io { }; /** - * Flags for fuse_lowlevel_notify_expire_entry() + * Flags for fuse_lowlevel_notify_entry() * 0 = invalidate entry * FUSE_LL_EXPIRE_ONLY = expire entry */ -enum fuse_expire_flags { +enum fuse_notify_entry_flags { + FUSE_LL_INVALIDATE = 0, FUSE_LL_EXPIRE_ONLY = (1 << 0), }; @@ -1682,8 +1683,7 @@ int fuse_lowlevel_notify_inval_inode(struct fuse_session *se, fuse_ino_t ino, off_t off, off_t len); /** - * Notify to invalidate parent attributes and the dentry matching - * parent/name + * Notify to invalidate parent attributes and the dentry matching parent/name * * To avoid a deadlock this function must not be called in the * execution path of a related filesystem operation or within any code @@ -1710,14 +1710,13 @@ int fuse_lowlevel_notify_inval_entry(struct fuse_session *se, fuse_ino_t parent, const char *name, size_t namelen); /** - * Notify to expire or invalidate parent attributes and the dentry - * matching parent/name + * Notify to expire parent attributes and the dentry matching parent/name * - * Underlying function for fuse_lowlevel_notify_inval_entry(). + * Same restrictions apply as for fuse_lowlevel_notify_inval_entry() * - * In addition to invalidating an entry, it also allows to expire an entry. - * In that case, the entry is not forcefully removed from kernel cache - * but instead the next access to it forces a lookup from the filesystem. + * Compared to invalidating an entry, expiring the entry results not in a + * forceful removal of that entry from kernel cache but instead the next access + * to it forces a lookup from the filesystem. * * This makes a difference for overmounted dentries, where plain invalidation * would detach all submounts before dropping the dentry from the cache. @@ -1728,17 +1727,18 @@ int fuse_lowlevel_notify_inval_entry(struct fuse_session *se, fuse_ino_t parent, * so invalidation will only be triggered for the non-overmounted case. * The dentry could also be mounted in a different mount instance, in which case * any submounts will still be detached. + * + * Added in FUSE protocol version 7.38. If the kernel does not support + * this (or a newer) version, the function will return -ENOSYS and do nothing. * * @param se the session object * @param parent inode number * @param name file name * @param namelen strlen() of file name - * @param flags flags to control if the entry should be expired or invalidated - * @return zero for success, -errno for failure + * @return zero for success, -errno for failure, -enosys if no kernel support */ int fuse_lowlevel_notify_expire_entry(struct fuse_session *se, fuse_ino_t parent, - const char *name, size_t namelen, - enum fuse_expire_flags flags); + const char *name, size_t namelen); /** * This function behaves like fuse_lowlevel_notify_inval_entry() with diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c index 1ce6083..4b9ee89 100644 --- a/lib/fuse_lowlevel.c +++ b/lib/fuse_lowlevel.c @@ -2305,9 +2305,28 @@ int fuse_lowlevel_notify_inval_inode(struct fuse_session *se, fuse_ino_t ino, return send_notify_iov(se, FUSE_NOTIFY_INVAL_INODE, iov, 2); } -int fuse_lowlevel_notify_expire_entry(struct fuse_session *se, fuse_ino_t parent, - const char *name, size_t namelen, - enum fuse_expire_flags flags) +/** + * Notify parent attributes and the dentry matching parent/name + * + * Underlying base function for fuse_lowlevel_notify_inval_entry() and + * fuse_lowlevel_notify_expire_entry(). + * + * @warning + * Only checks if fuse_lowlevel_notify_inval_entry() is supported by + * the kernel. All other flags will fall back to + * fuse_lowlevel_notify_inval_entry() if not supported! + * DO THE PROPER CHECKS IN THE DERIVED FUNCTION! + * + * @param se the session object + * @param parent inode number + * @param name file name + * @param namelen strlen() of file name + * @param flags flags to control if the entry should be expired or invalidated + * @return zero for success, -errno for failure +*/ +static int fuse_lowlevel_notify_entry(struct fuse_session *se, fuse_ino_t parent, + const char *name, size_t namelen, + enum fuse_notify_entry_flags flags) { struct fuse_notify_inval_entry_out outarg; struct iovec iov[3]; @@ -2333,9 +2352,21 @@ int fuse_lowlevel_notify_expire_entry(struct fuse_session *se, fuse_ino_t parent } int fuse_lowlevel_notify_inval_entry(struct fuse_session *se, fuse_ino_t parent, - const char *name, size_t namelen) + const char *name, size_t namelen) +{ + return fuse_lowlevel_notify_entry(se, parent, name, namelen, FUSE_LL_INVALIDATE); +} + +int fuse_lowlevel_notify_expire_entry(struct fuse_session *se, fuse_ino_t parent, + const char *name, size_t namelen) { - return fuse_lowlevel_notify_expire_entry(se, parent, name, namelen, 0); + if (!se) + return -EINVAL; + + if (!(se->conn.capable & FUSE_CAP_EXPIRE_ONLY)) + return -ENOSYS; + + return fuse_lowlevel_notify_entry(se, parent, name, namelen, FUSE_LL_EXPIRE_ONLY); } diff --git a/test/test_examples.py b/test/test_examples.py index 958e633..96e4108 100755 --- a/test/test_examples.py +++ b/test/test_examples.py @@ -347,6 +347,8 @@ def test_notify_inval_entry(tmpdir, only_expire, notify, output_checker): cmdline.append('--no-notify') if only_expire == "expire_entries": cmdline.append('--only-expire') + if fuse_proto < (7,38): + pytest.skip('only-expire not supported by running kernel') mount_process = subprocess.Popen(cmdline, stdout=output_checker.fd, stderr=output_checker.fd) try: