From: Eric Sandeen Subject: Re: [PATCH] e4defrag: Add option -m mtab to e4defrag Date: Wed, 17 Oct 2012 12:06:58 -0500 Message-ID: <507EE5B2.3000506@redhat.com> References: <1350492760-2106-1-git-send-email-ashish.sangwan2@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: tytso@mit.edu, linux-ext4@vger.kernel.org, Namjae Jeon To: Ashish Sangwan Return-path: Received: from mx1.redhat.com ([209.132.183.28]:1056 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757439Ab2JQRHC (ORCPT ); Wed, 17 Oct 2012 13:07:02 -0400 In-Reply-To: <1350492760-2106-1-git-send-email-ashish.sangwan2@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 10/17/12 11:52 AM, Ashish Sangwan wrote: > Currently, e4defrag will not work on machines where /etc/mtab is not present > OR is empty. > This patch does 3 things: > a) Add option "-m mtab" to e4defrag so that user can specify any file to > be scanned for otbtaining mounted filesystems info. Under what conditions would this be useful; i.e. when is mtab information ever in a file other than /etc/mtab? Thanks, -Eric > b) If mtab option is not specified, first we try to scan /proc/mounts, if failed > to access this file, we try with /etc/mtab. > c) In function is_ext4, check if the varibale "mnt_type" is null before > calling strcmp, otherwise segfault would occur if mtab is empty. > > Signed-off-by: Ashish Sangwan > Signed-off-by: Namjae Jeon > --- > misc/e4defrag.8.in | 10 ++++++++++ > misc/e4defrag.c | 34 ++++++++++++++++++++++------------ > 2 files changed, 32 insertions(+), 12 deletions(-) > > diff --git a/misc/e4defrag.8.in b/misc/e4defrag.8.in > index 75e1bc9..7090e51 100644 > --- a/misc/e4defrag.8.in > +++ b/misc/e4defrag.8.in > @@ -9,6 +9,9 @@ e4defrag \- online defragmenter for ext4 filesystem > [ > .B \-v > ] > +[ > +.B \-m mtab > +] > .I target > \&... > .SH DESCRIPTION > @@ -57,6 +60,13 @@ is never defragmented. > .B \-v > Print error messages and the fragmentation count before and after defrag for > each file. > +.TP > +.B \-m mtab > +This option will specify the file to be scanned for obtaining mounted filesystems > +information. If this option is not specified, the default is to use > +.B /proc/mounts . > +If this file is not accessible, e4defrag will try to get required information from > +.B /etc/mtab > .SH NOTES > .B e4defrag > does not support swap file, files in lost+found directory, and files allocated > diff --git a/misc/e4defrag.c b/misc/e4defrag.c > index 4b31d03..3567e9f 100644 > --- a/misc/e4defrag.c > +++ b/misc/e4defrag.c > @@ -123,6 +123,7 @@ > #define NGMSG_FILE_OPEN "Failed to open" > #define NGMSG_FILE_UNREG "File is not regular file" > #define NGMSG_LOST_FOUND "Can not process \"lost+found\"" > +#define _PATH_PROC_MOUNTS "/proc/mounts" > > /* Data type for filesystem-wide blocks number */ > typedef unsigned long long ext4_fsblk_t; > @@ -262,10 +263,8 @@ static int fallocate64(int fd, int mode, loff_t offset, loff_t len) > * @dir_path_len: the length of directory. > */ > static int get_mount_point(const char *devname, char *mount_point, > - int dir_path_len) > + int dir_path_len, const char *mtab) > { > - /* Refer to /etc/mtab */ > - const char *mtab = MOUNTED; > FILE *fp = NULL; > struct mntent *mnt = NULL; > struct stat64 sb; > @@ -278,7 +277,7 @@ static int get_mount_point(const char *devname, char *mount_point, > > fp = setmntent(mtab, "r"); > if (fp == NULL) { > - perror("Couldn't access /etc/mtab"); > + printf("Couldn't access %s\n", mtab); > return -1; > } > > @@ -313,14 +312,12 @@ static int get_mount_point(const char *devname, char *mount_point, > * > * @file: the file's name. > */ > -static int is_ext4(const char *file, char *devname) > +static int is_ext4(const char *file, char *devname, const char *mtab) > { > int maxlen = 0; > int len, ret; > FILE *fp = NULL; > char *mnt_type = NULL; > - /* Refer to /etc/mtab */ > - const char *mtab = MOUNTED; > char file_path[PATH_MAX + 1]; > struct mntent *mnt = NULL; > struct statfs64 fsbuf; > @@ -345,7 +342,7 @@ static int is_ext4(const char *file, char *devname) > > fp = setmntent(mtab, "r"); > if (fp == NULL) { > - perror("Couldn't access /etc/mtab"); > + printf("Couldn't access %s", mtab); > return -1; > } > > @@ -374,6 +371,10 @@ static int is_ext4(const char *file, char *devname) > } > > endmntent(fp); > + if (mnt_type == NULL) { > + printf("Could not get mount information from %s\n", mtab); > + return -1; > + } > if (strcmp(mnt_type, FS_EXT4) == 0) { > FREE(mnt_type); > return 0; > @@ -1724,6 +1725,7 @@ int main(int argc, char *argv[]) > int success_flag = 0; > char dir_name[PATH_MAX + 1]; > char dev_name[PATH_MAX + 1]; > + char *mtab = NULL; > struct stat64 buf; > ext2_filsys fs = NULL; > > @@ -1731,7 +1733,7 @@ int main(int argc, char *argv[]) > if (argc == 1) > goto out; > > - while ((opt = getopt(argc, argv, "vc")) != EOF) { > + while ((opt = getopt(argc, argv, "vcm:")) != EOF) { > switch (opt) { > case 'v': > mode_flag |= DETAIL; > @@ -1739,11 +1741,19 @@ int main(int argc, char *argv[]) > case 'c': > mode_flag |= STATISTIC; > break; > + case 'm': > + mtab = optarg; > + break; > default: > goto out; > } > } > - > + if (!mtab) { > + if (access(_PATH_PROC_MOUNTS, R_OK) == 0) > + mtab = _PATH_PROC_MOUNTS; > + else > + mtab = _PATH_MOUNTED; > + } > if (argc == optind) > goto out; > > @@ -1797,7 +1807,7 @@ int main(int argc, char *argv[]) > if (S_ISBLK(buf.st_mode)) { > /* Block device */ > strncpy(dev_name, argv[i], strnlen(argv[i], PATH_MAX)); > - if (get_mount_point(argv[i], dir_name, PATH_MAX) < 0) > + if (get_mount_point(argv[i], dir_name, PATH_MAX, mtab) < 0) > continue; > if (lstat64(dir_name, &buf) < 0) { > perror(NGMSG_FILE_INFO); > @@ -1833,7 +1843,7 @@ int main(int argc, char *argv[]) > * filesystem type checked in get_mount_point() > */ > if (arg_type == FILENAME || arg_type == DIRNAME) { > - if (is_ext4(argv[i], dev_name) < 0) > + if (is_ext4(argv[i], dev_name, mtab) < 0) > continue; > if (realpath(argv[i], dir_name) == NULL) { > perror("Couldn't get full path"); >