Re: [PATCH 2/4] src/open_by_handle: flexible usage options

Eryu Guan
2017-04-19T09:42:05Z

On Tue, Apr 18, 2017 at 09:17:22PM +0300, Amir Goldstein wrote:
> More usage options for testing open_by_handle, which are needed
> for testing stable handles across copy up in overlayfs.
>
> usage: open_by_handle [-c|-l|-u|-d] <test_dir> [num_files]
>
> Examples:
>
> 1. Create N test files (nlink=1) under test_dir and exit:
> $ open_by_handle -c <test_dir> [N]
>
> 2. Get file handles, drop caches and try to open by handle
> (expects success):
> $ open_by_handle <test_dir> [N]
>
> 3. Get file handles, create hardlinks to test files (nlink=2),
> drop caches and try to open by handle (expects success):
> $ open_by_handle -l <test_dir> [N]
>
> 4. Get file handles, unlink test files w/o the hardlinks (nlink=1),
> drop caches and try to open by handle (expects success):
> $ open_by_handle -u <test_dir> [N]
>
> 5. Get file handles, unlink test files and hardlinks (nlink=0),
> drop caches and try to open by handle (expects failure):
> $ open_by_handle -d <test_dir> [N]

"The reason I separated -l (link) and -u (unlink) is because for
overlayfs I need to test linking in lower layer and unlinking from
overlay."

I think it's better to have this in commit log too. (And more
description of the usages of these options? I found that "-c" only
creates test files not hard links, so a subsequent "-u" reports ESTALE,
"-u" is only valid after a "-l". This could confuse testers, I guess.)

>
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> ---
> src/open_by_handle.c | 93 ++++++++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 80 insertions(+), 13 deletions(-)
>
> diff --git a/src/open_by_handle.c b/src/open_by_handle.c
> index 8f04865..c33a4aa 100644
> --- a/src/open_by_handle.c
> +++ b/src/open_by_handle.c
> @@ -37,12 +37,12 @@
> #include <errno.h>
> #include <linux/limits.h>
>
> -#define NUMFILES 1024
> +#define MAXFILES 1024
>
> struct handle {
> struct file_handle fh;
> unsigned char fid[MAX_HANDLE_SZ];
> -} handle[NUMFILES];
> +} handle[MAXFILES];
>
> int main(int argc, char **argv)
> {
> @@ -51,18 +51,60 @@ int main(int argc, char **argv)
> int ret;
> int failed = 0;
> char fname[PATH_MAX];
> + char fname2[PATH_MAX];
> char *test_dir;
> int mount_fd, mount_id;
> + int argi = 1, numfiles = 1;
> + int create = 0, delete = 0, nlink = 1;
>
> - if (argc != 2) {
> - fprintf(stderr, "usage: open_by_handle <test_dir>\n");
> + if (argc < 2 || argc > 4) {
> +usage:
> + fprintf(stderr, "usage: open_by_handle [-c|-l|-u|-d] <test_dir> [num_files]\n");
> + fprintf(stderr, "\n");
> + fprintf(stderr, "open_by_handle -c <test_dir> [N] - create N test files under test_dir, get file handles and exit\n");
> + fprintf(stderr, "open_by_handle <test_dir> [N] - get file handles, drop caches and try to open by handle (expects success)\n");
> + fprintf(stderr, "open_by_handle -l <test_dir> [N] - get file handles, create hardlinks to test files (nlink=2), drop caches and try to open by handle (expects success)\n");
> + fprintf(stderr, "open_by_handle -u <test_dir> [N] - get file handles, unlink test files w/o hardlinks (nlink=1), drop caches and try to open by handle (expects success)\n");
> + fprintf(stderr, "open_by_handle -d <test_dir> [N] - get file handles, unlink test files and hardlinks (nlink=0), drop caches and try to open by handle (expects failure)\n");
> return EXIT_FAILURE;
> }
>
> - test_dir = argv[1];
> + if (argv[1][0] == '-') {

Hmm, why not "getopt"?

> + if (argv[1][2])
> + goto usage;
> + switch (argv[1][1]) {
> + case 'c':
> + create = 1;
> + break;
> + case 'l':
> + nlink = 2;
> + break;
> + case 'u':
> + delete = 1;
> + nlink = 1;
> + break;
> + case 'd':
> + delete = 1;
> + nlink = 0;
> + break;
> + default:
> + fprintf(stderr, "illegal option '%s'\n", argv[1]);
> + case 'h':
> + goto usage;
> + }
> + argi++;
> + }
> + test_dir = argv[argi++];
> + if (argc > argi)
> + numfiles = atoi(argv[argi]);
> + if (!numfiles || numfiles > MAXFILES) {
> + fprintf(stderr, "illegal value '%s' for num_files\n", argv[argi]);
> + goto usage;
> + }
> +
> mount_fd = open(test_dir, O_RDONLY|O_DIRECTORY);
> if (mount_fd < 0) {
> - perror("open test_dir");
> + perror(test_dir);
> return EXIT_FAILURE;
> }
>
> @@ -70,8 +112,9 @@ int main(int argc, char **argv)
> * create a large number of files to force allocation of new inode
> * chunks on disk.
> */
> - for (i=0; i < NUMFILES; i++) {
> + for (i=0; create && i < numfiles; i++) {
> sprintf(fname, "%s/file%06d", test_dir, i);
> + sprintf(fname2, "%s/link%06d", test_dir, i);
> fd = open(fname, O_RDWR | O_CREAT | O_TRUNC, 0644);
> if (fd < 0) {
> printf("Warning (%s,%d), open(%s) failed.\n", __FILE__, __LINE__, fname);
> @@ -79,13 +122,14 @@ int main(int argc, char **argv)
> return EXIT_FAILURE;
> }
> close(fd);
> + ret = unlink(fname2);

So "-c" also implies unlinking the hard links, mind updating the commit
log and the comment above the for block?

But I'm not sure if it's a good idea for the test to depend on this
subtle cleanup behavior, see my comments to patch #4.

> }
>
> /* sync to get the new inodes to hit the disk */
> sync();
>
> /* create the handles */
> - for (i=0; i < NUMFILES; i++) {
> + for (i=0; i < numfiles; i++) {
> sprintf(fname, "%s/file%06d", test_dir, i);
> handle[i].fh.handle_bytes = MAX_HANDLE_SZ;
> ret = name_to_handle_at(AT_FDCWD, fname, &handle[i].fh, &mount_id, 0);
> @@ -95,14 +139,32 @@ int main(int argc, char **argv)
> }
> }
>
> + /* after creating test set only check that fs supports exportfs */
> + if (create)
> + return EXIT_SUCCESS;

"-c" means "Create N test files (nlink=1) under test_dir and exit", so
we could move it before name_to_handle_at() calls?

> +
> + /* hardlink the files */
> + for (i=0; nlink > 1 && i < numfiles; i++) {
> + sprintf(fname, "%s/file%06d", test_dir, i);
> + sprintf(fname2, "%s/link%06d", test_dir, i);
> + ret = link(fname, fname2);
> + if (ret < 0) {
> + perror("link");
> + return EXIT_FAILURE;
> + }
> + }
> +
> /* unlink the files */
> - for (i=0; i < NUMFILES; i++) {
> + for (i=0; delete && i < numfiles; i++) {
> sprintf(fname, "%s/file%06d", test_dir, i);
> + sprintf(fname2, "%s/link%06d", test_dir, i);
> ret = unlink(fname);
> if (ret < 0) {
> perror("unlink");
> return EXIT_FAILURE;
> }
> + if (!nlink)
> + ret = unlink(fname2);

I noticed that return values of unlink(fname2) are all ignored, is this
intentional?

> }
>
> /* sync to get log forced for unlink transactions to hit the disk */
> @@ -126,17 +188,22 @@ int main(int argc, char **argv)
> * now try to open the files by the stored handles. Expecting ENOENT
> * for all of them.

These comments should be updated too.

Thanks,
Eryu

> */
> - for (i=0; i < NUMFILES; i++) {
> + for (i=0; i < numfiles; i++) {
> errno = 0;
> fd = open_by_handle_at(mount_fd, &handle[i].fh, O_RDWR);
> - if (fd < 0 && (errno == ENOENT || errno == ESTALE)) {
> + if (nlink && fd >= 0) {
> + close(fd);
> + continue;
> + } else if (!nlink && fd < 0 && (errno == ENOENT || errno == ESTALE)) {
> continue;
> }
> if (fd >= 0) {
> printf("open_by_handle(%d) opened an unlinked file!\n", i);
> close(fd);
> - } else
> - printf("open_by_handle(%d) returned %d incorrectly on an unlinked file!\n", i, errno);
> + } else {
> + printf("open_by_handle(%d) returned %d incorrectly on %s file!\n", i, errno,
> + nlink ? "a linked" : "an unlinked");
> + }
> failed++;
> }
> if (failed)
> --
> 2.7.4
>