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lock-util: make global lock return parameter to image_path_lock() optional

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When adding unprivileged nspawn support we don't really want a global
lock file, since we cannot even access the dir they are stored in, hence
make the concept optional.

Some minor other modernizations.
This commit is contained in:
Lennart Poettering
2024-04-06 16:08:23 +02:00
parent 0f716ace41
commit cb1b813f0d
2 changed files with 29 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/basic/lock-util.h
+1 -1
View File
@@ -17,7 +17,7 @@ static inline int make_lock_file(const char *p, int operation, LockFile *ret) {
int make_lock_file_for(const char *p, int operation, LockFile *ret);
void release_lock_file(LockFile *f);
#define LOCK_FILE_INIT { .dir_fd = -EBADF, .fd = -EBADF }
#define LOCK_FILE_INIT (LockFile) { .dir_fd = -EBADF, .fd = -EBADF }
/* POSIX locks with the same interface as flock(). */
int posix_lock(int fd, int operation);
src/shared/discover-image.c
+28 -18
View File
@@ -1295,7 +1295,12 @@ static void make_lock_dir(void) {
(void) mkdir("/run/systemd/nspawn/locks", 0700);
}
int image_path_lock(const char *path, int operation, LockFile *global, LockFile *local) {
int image_path_lock(
const char *path,
int operation,
LockFile *ret_global,
LockFile *ret_local) {
_cleanup_free_ char *p = NULL;
LockFile t = LOCK_FILE_INIT;
struct stat st;
@@ -1303,8 +1308,7 @@ int image_path_lock(const char *path, int operation, LockFile *global, LockFile
int r;
assert(path);
assert(global);
assert(local);
assert(ret_local);
/* Locks an image path. This actually creates two locks: one "local" one, next to the image path
* itself, which might be shared via NFS. And another "global" one, in /run, that uses the
@@ -1326,7 +1330,9 @@ int image_path_lock(const char *path, int operation, LockFile *global, LockFile
}
if (getenv_bool("SYSTEMD_NSPAWN_LOCK") == 0) {
*local = *global = (LockFile) LOCK_FILE_INIT;
*ret_local = LOCK_FILE_INIT;
if (ret_global)
*ret_global = LOCK_FILE_INIT;
return 0;
}
@@ -1342,19 +1348,23 @@ int image_path_lock(const char *path, int operation, LockFile *global, LockFile
if (exclusive)
return -EBUSY;
*local = *global = (LockFile) LOCK_FILE_INIT;
*ret_local = LOCK_FILE_INIT;
if (ret_global)
*ret_global = LOCK_FILE_INIT;
return 0;
}
if (stat(path, &st) >= 0) {
if (S_ISBLK(st.st_mode))
r = asprintf(&p, "/run/systemd/nspawn/locks/block-%u:%u", major(st.st_rdev), minor(st.st_rdev));
else if (S_ISDIR(st.st_mode) || S_ISREG(st.st_mode))
r = asprintf(&p, "/run/systemd/nspawn/locks/inode-%lu:%lu", (unsigned long) st.st_dev, (unsigned long) st.st_ino);
else
return -ENOTTY;
if (r < 0)
return -ENOMEM;
if (ret_global) {
if (stat(path, &st) >= 0) {
if (S_ISBLK(st.st_mode))
r = asprintf(&p, "/run/systemd/nspawn/locks/block-%u:%u", major(st.st_rdev), minor(st.st_rdev));
else if (S_ISDIR(st.st_mode) || S_ISREG(st.st_mode))
r = asprintf(&p, "/run/systemd/nspawn/locks/inode-%lu:%lu", (unsigned long) st.st_dev, (unsigned long) st.st_ino);
else
return -ENOTTY;
if (r < 0)
return -ENOMEM;
}
}
/* For block devices we don't need the "local" lock, as the major/minor lock above should be
@@ -1372,15 +1382,15 @@ int image_path_lock(const char *path, int operation, LockFile *global, LockFile
if (p) {
make_lock_dir();
r = make_lock_file(p, operation, global);
r = make_lock_file(p, operation, ret_global);
if (r < 0) {
release_lock_file(&t);
return r;
}
} else
*global = (LockFile) LOCK_FILE_INIT;
} else if (ret_global)
*ret_global = LOCK_FILE_INIT;
*local = t;
*ret_local = t;
return 0;
}