From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: [PATCH 2/3] contrib: add thread locking and readdir64_r support to spd_readdir Date: Mon, 21 Jan 2013 19:09:49 -0500 Message-ID: <1358813390-26466-2-git-send-email-tytso@mit.edu> References: <1358813390-26466-1-git-send-email-tytso@mit.edu> Cc: Theodore Ts'o To: Ext4 Developers List Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:44700 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751563Ab3AVAJ4 (ORCPT ); Mon, 21 Jan 2013 19:09:56 -0500 In-Reply-To: <1358813390-26466-1-git-send-email-tytso@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: This is part of a series of improvements from a 2008 version of spd_readdir.c that somehow didn't make it into the version which we checked into e2fsprogs git tree. Signed-off-by: "Theodore Ts'o" --- contrib/spd_readdir.c | 75 ++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 57 insertions(+), 18 deletions(-) diff --git a/contrib/spd_readdir.c b/contrib/spd_readdir.c index 30c01b3..910b104 100644 --- a/contrib/spd_readdir.c +++ b/contrib/spd_readdir.c @@ -1,21 +1,22 @@ /* * readdir accelerator * - * (C) Copyright 2003, 2004 by Theodore Ts'o. + * (C) Copyright 2003, 2004, 2008 by Theodore Ts'o. + * + * 2008-06-08 Modified by Ross Boylan + * Added support for readdir_r and readdir64_r calls. Note + * this has not been tested on anything other than GNU/Linux i386, + * and that the regular readdir wrapper will take slightly more + * space than Ted's original since it now includes a lock. * * Compile using the command: * - * gcc -o spd_readdir.so -fPIC -shared spd_readdir.c -ldl + * gcc -o spd_readdir.so -shared -fpic spd_readdir.c -ldl * * Use it by setting the LD_PRELOAD environment variable: * * export LD_PRELOAD=/usr/local/sbin/spd_readdir.so * - * Note that this preload is not going to work for all programs. In - * particular, although it does supply readdir_r(), it is *not* thread - * safe. So I can't recommend this as something to be dropped in - * /etc/ld.so.preload. - * * %Begin-Header% * This file may be redistributed under the terms of the GNU Public * License. @@ -55,6 +56,7 @@ #else #define PR_GET_DUMPABLE 3 #endif +#include struct dirent_s { unsigned long long d_ino; @@ -66,6 +68,7 @@ struct dirent_s { struct dir_s { DIR *dir; + pthread_mutex_t lock; /* Mutex lock for this structure. */ int num; int max; struct dirent_s *dp; @@ -83,6 +86,8 @@ static struct dirent *(*real_readdir)(DIR *dir) = 0; static int (*real_readdir_r)(DIR *dir, struct dirent *entry, struct dirent **result) = 0; static struct dirent64 *(*real_readdir64)(DIR *dir) = 0; +static int (*real_readdir64_r)(DIR *dir, struct dirent64 *entry, + struct dirent64 **result) = 0; static off_t (*real_telldir)(DIR *dir) = 0; static void (*real_seekdir)(DIR *dir, off_t offset) = 0; static int (*real_dirfd)(DIR *dir) = 0; @@ -124,6 +129,7 @@ static void setup_ptr() real_readdir = dlsym(RTLD_NEXT, "readdir"); real_readdir_r = dlsym(RTLD_NEXT, "readdir_r"); real_readdir64 = dlsym(RTLD_NEXT, "readdir64"); + real_readdir64_r = dlsym(RTLD_NEXT, "readdir64_r"); real_telldir = dlsym(RTLD_NEXT, "telldir"); real_seekdir = dlsym(RTLD_NEXT, "seekdir"); real_dirfd = dlsym(RTLD_NEXT, "dirfd"); @@ -142,6 +148,8 @@ static void free_cached_dir(struct dir_s *dirstruct) { int i; + pthread_mutex_destroy(&(dirstruct->lock)); + if (!dirstruct->dp) return; @@ -181,11 +189,14 @@ static int ino_cmp(const void *a, const void *b) struct dir_s *alloc_dirstruct(DIR *dir) { struct dir_s *dirstruct; + static pthread_mutexattr_t mutexattr; + mutexattr.__align = PTHREAD_MUTEX_RECURSIVE; dirstruct = malloc(sizeof(struct dir_s)); if (dirstruct) memset(dirstruct, 0, sizeof(struct dir_s)); dirstruct->dir = dir; + pthread_mutex_init(&(dirstruct->lock), &mutexattr); return dirstruct; } @@ -268,7 +279,7 @@ DIR *fdopendir(int fd) if (!real_fdopendir) setup_ptr(); - DEBUG_DIR(printf("fdpendir(%d) (%d open)\n", fd, num_open++)); + DEBUG_DIR(printf("fdopendir(%d) (%d open)\n", fd, num_open++)); dir = (*real_fdopendir)(fd); if (!dir) return NULL; @@ -336,19 +347,19 @@ int readdir_r(DIR *dir, struct dirent *entry, struct dirent **result) if (dirstruct->direct) return (*real_readdir_r)(dirstruct->dir, entry, result); + pthread_mutex_lock(&(dirstruct->lock)); if (dirstruct->pos >= dirstruct->num) { *result = NULL; - return 0; + } else { + ds = &dirstruct->dp[dirstruct->pos++]; + entry->d_ino = ds->d_ino; + entry->d_off = ds->d_off; + entry->d_reclen = ds->d_reclen; + entry->d_type = ds->d_type; + strncpy(entry->d_name, ds->d_name, sizeof(entry->d_name)); + *result = entry; } - - ds = &dirstruct->dp[dirstruct->pos++]; - entry->d_ino = ds->d_ino; - entry->d_off = ds->d_off; - entry->d_reclen = ds->d_reclen; - entry->d_type = ds->d_type; - strncpy(entry->d_name, ds->d_name, sizeof(entry->d_name)); - *result = entry; - + pthread_mutex_unlock(&(dirstruct->lock)); return 0; } @@ -374,6 +385,32 @@ struct dirent64 *readdir64(DIR *dir) return (&dirstruct->ret_dir64); } +int readdir64_r (DIR *__restrict dir, + struct dirent64 *__restrict entry, + struct dirent64 **__restrict result) +{ + struct dir_s *dirstruct = (struct dir_s *) dir; + struct dirent_s *ds; + + if (dirstruct->direct) + return (*real_readdir64_r)(dir, entry, result); + pthread_mutex_lock(&(dirstruct->lock)); + if (dirstruct->pos >= dirstruct->num) { + *result = NULL; + } else { + ds = &dirstruct->dp[dirstruct->pos++]; + entry->d_ino = ds->d_ino; + entry->d_off = ds->d_off; + entry->d_reclen = ds->d_reclen; + entry->d_type = ds->d_type; + strncpy(entry->d_name, ds->d_name, + sizeof(entry->d_name)); + *result = entry; + } + pthread_mutex_unlock(&(dirstruct->lock)); + return 0; +} + off_t telldir(DIR *dir) { struct dir_s *dirstruct = (struct dir_s *) dir; @@ -404,9 +441,11 @@ void rewinddir(DIR *dir) if (dirstruct->direct) return; + pthread_mutex_lock(&(dirstruct->lock)); dirstruct->pos = 0; free_cached_dir(dirstruct); cache_dirstruct(dirstruct); + pthread_mutex_unlock(&(dirstruct->lock)); } int dirfd(DIR *dir) -- 1.7.12.rc0.22.gcdd159b