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Date: Wed, 17 Oct 2012 12:06:58 -0500
From: Eric Sandeen <sandeen@...hat.com>
To: Ashish Sangwan <ashishsangwan2@...il.com>
CC: tytso@....edu, linux-ext4@...r.kernel.org,
Namjae Jeon <linkinjeon@...il.com>
Subject: Re: [PATCH] e4defrag: Add option -m mtab to e4defrag
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 <ashish.sangwan2@...il.com>
> Signed-off-by: Namjae Jeon <linkinjeon@...il.com>
> ---
> 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");
>
--
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