loopdev: use LOOP_CONFIG ioctl

Prefer to use the new LOOP_CONFIG ioctl.
https://lwn.net/Articles/820408/

Signed-off-by: Sinan Kaya <sinan.kaya@microsoft.com>

diff --git a/include/loopdev.h b/include/loopdev.h
index 65bd579d2309fae04ab776fdc0468549db0ee614..bcc7bfa735b2a7fa8c6920c1bb6a45d813050e48 100644 (file)
--- a/include/loopdev.h
+++ b/include/loopdev.h
@@ -66,6 +66,16 @@ struct loop_info64 {
        uint64_t        lo_init[2];
 };
 
+#ifndef LOOP_CONFIGURE
+#define LOOP_CONFIGURE 0x4C0A
+struct loop_config {
+  uint32_t fd;
+  uint32_t block_size;
+  struct loop_info64 info;
+  uint64_t __reserved[8];
+};
+#endif
+
 #define LOOPDEV_MAJOR          7       /* loop major number */
 #define LOOPDEV_DEFAULT_NNODES 8       /* default number of loop devices */
 
@@ -105,7 +115,7 @@ struct loopdev_cxt {
        unsigned int    control_ok:1;   /* /dev/loop-control success */
 
        struct path_cxt         *sysfs; /* pointer to /sys/dev/block/<maj:min>/ */
-       struct loop_info64      info;   /* for GET/SET ioctl */
+       struct loop_config      config; /* for GET/SET ioctl */
        struct loopdev_iter     iter;   /* scans /sys or /dev for used/free devices */
 };
 

diff --git a/lib/loopdev.c b/lib/loopdev.c
index c4b492dc5f6bf48592205709b1563c18c4bad86c..15264b19c172f1ce3145d6763a44db1e82a4220a 100644 (file)
--- a/lib/loopdev.c
+++ b/lib/loopdev.c
@@ -100,7 +100,7 @@ int loopcxt_set_device(struct loopdev_cxt *lc, const char *device)
        lc->has_info = 0;
        lc->info_failed = 0;
        *lc->device = '\0';
-       memset(&lc->info, 0, sizeof(lc->info));
+       memset(&lc->config, 0, sizeof(lc->config));
 
        /* set new */
        if (device) {
@@ -659,17 +659,17 @@ struct loop_info64 *loopcxt_get_info(struct loopdev_cxt *lc)
        }
        errno = 0;
        if (lc->has_info)
-               return &lc->info;
+               return &lc->config.info;
 
        fd = loopcxt_get_fd(lc);
        if (fd < 0)
                return NULL;
 
-       if (ioctl(fd, LOOP_GET_STATUS64, &lc->info) == 0) {
+       if (ioctl(fd, LOOP_GET_STATUS64, &lc->config.info) == 0) {
                lc->has_info = 1;
                lc->info_failed = 0;
                DBG(CXT, ul_debugobj(lc, "reading loop_info64 OK"));
-               return &lc->info;
+               return &lc->config.info;
        }
 
        lc->info_failed = 1;
@@ -1087,7 +1087,7 @@ int loopcxt_set_offset(struct loopdev_cxt *lc, uint64_t offset)
 {
        if (!lc)
                return -EINVAL;
-       lc->info.lo_offset = offset;
+       lc->config.info.lo_offset = offset;
 
        DBG(CXT, ul_debugobj(lc, "set offset=%jd", offset));
        return 0;
@@ -1100,7 +1100,7 @@ int loopcxt_set_sizelimit(struct loopdev_cxt *lc, uint64_t sizelimit)
 {
        if (!lc)
                return -EINVAL;
-       lc->info.lo_sizelimit = sizelimit;
+       lc->config.info.lo_sizelimit = sizelimit;
 
        DBG(CXT, ul_debugobj(lc, "set sizelimit=%jd", sizelimit));
        return 0;
@@ -1134,7 +1134,7 @@ int loopcxt_set_flags(struct loopdev_cxt *lc, uint32_t flags)
 {
        if (!lc)
                return -EINVAL;
-       lc->info.lo_flags = flags;
+       lc->config.info.lo_flags = flags;
 
        DBG(CXT, ul_debugobj(lc, "set flags=%u", (unsigned) flags));
        return 0;
@@ -1157,9 +1157,9 @@ int loopcxt_set_backing_file(struct loopdev_cxt *lc, const char *filename)
        if (!lc->filename)
                return -errno;
 
-       xstrncpy((char *)lc->info.lo_file_name, lc->filename, LO_NAME_SIZE);
+       xstrncpy((char *)lc->config.info.lo_file_name, lc->filename, LO_NAME_SIZE);
 
-       DBG(CXT, ul_debugobj(lc, "set backing file=%s", lc->info.lo_file_name));
+       DBG(CXT, ul_debugobj(lc, "set backing file=%s", lc->config.info.lo_file_name));
        return 0;
 }
 
@@ -1182,7 +1182,7 @@ static int loopcxt_check_size(struct loopdev_cxt *lc, int file_fd)
        int dev_fd;
        struct stat st;
 
-       if (!lc->info.lo_offset && !lc->info.lo_sizelimit)
+       if (!lc->config.info.lo_offset && !lc->config.info.lo_sizelimit)
                return 0;
 
        if (fstat(file_fd, &st)) {
@@ -1198,16 +1198,16 @@ static int loopcxt_check_size(struct loopdev_cxt *lc, int file_fd)
        } else
                expected_size = st.st_size;
 
-       if (expected_size == 0 || expected_size <= lc->info.lo_offset) {
+       if (expected_size == 0 || expected_size <= lc->config.info.lo_offset) {
                DBG(CXT, ul_debugobj(lc, "failed to determine expected size"));
                return 0;       /* ignore this error */
        }
 
-       if (lc->info.lo_offset > 0)
-               expected_size -= lc->info.lo_offset;
+       if (lc->config.info.lo_offset > 0)
+               expected_size -= lc->config.info.lo_offset;
 
-       if (lc->info.lo_sizelimit > 0 && lc->info.lo_sizelimit < expected_size)
-               expected_size = lc->info.lo_sizelimit;
+       if (lc->config.info.lo_sizelimit > 0 && lc->config.info.lo_sizelimit < expected_size)
+               expected_size = lc->config.info.lo_sizelimit;
 
        dev_fd = loopcxt_get_fd(lc);
        if (dev_fd < 0) {
@@ -1275,6 +1275,7 @@ int loopcxt_setup_device(struct loopdev_cxt *lc)
 {
        int file_fd, dev_fd, mode = O_RDWR, rc = -1, cnt = 0, err, again;
        int errsv = 0;
+       int fallback = 0;
 
        if (!lc || !*lc->device || !lc->filename)
                return -EINVAL;
@@ -1284,7 +1285,7 @@ int loopcxt_setup_device(struct loopdev_cxt *lc)
        /*
         * Open backing file and device
         */
-       if (lc->info.lo_flags & LO_FLAGS_READ_ONLY)
+       if (lc->config.info.lo_flags & LO_FLAGS_READ_ONLY)
                mode = O_RDONLY;
 
        if ((file_fd = open(lc->filename, mode | O_CLOEXEC)) < 0) {
@@ -1307,10 +1308,10 @@ int loopcxt_setup_device(struct loopdev_cxt *lc)
 
        if (mode == O_RDONLY) {
                lc->flags |= LOOPDEV_FL_RDONLY;                 /* open() mode */
-               lc->info.lo_flags |= LO_FLAGS_READ_ONLY;        /* kernel loopdev mode */
+               lc->config.info.lo_flags |= LO_FLAGS_READ_ONLY; /* kernel loopdev mode */
        } else {
                lc->flags |= LOOPDEV_FL_RDWR;                   /* open() mode */
-               lc->info.lo_flags &= ~LO_FLAGS_READ_ONLY;
+               lc->config.info.lo_flags &= ~LO_FLAGS_READ_ONLY;
                lc->flags &= ~LOOPDEV_FL_RDONLY;
        }
 
@@ -1334,45 +1335,69 @@ int loopcxt_setup_device(struct loopdev_cxt *lc)
 
        DBG(SETUP, ul_debugobj(lc, "device open: OK"));
 
-       /*
-        * Set FD
-        */
-       if (ioctl(dev_fd, LOOP_SET_FD, file_fd) < 0) {
+       lc->config.fd = file_fd;
+       if (ioctl(dev_fd, LOOP_CONFIGURE, &lc->config) < 0) {
                rc = -errno;
                errsv = errno;
-               DBG(SETUP, ul_debugobj(lc, "LOOP_SET_FD failed: %m"));
-               goto err;
+               if (errno != EINVAL)
+               {
+                       DBG(SETUP, ul_debugobj(lc, "LOOP_CONFIGURE failed: %m"));
+                       goto err;
+               }
+               fallback = 1;
        }
+       else
+       {
+               if (lc->blocksize > 0
+                       && (rc = loopcxt_ioctl_blocksize(lc, lc->blocksize)) < 0) {
+                       errsv = -rc;
+                       goto err;
+               }
 
-       DBG(SETUP, ul_debugobj(lc, "LOOP_SET_FD: OK"));
-
-       if (lc->blocksize > 0
-           && (rc = loopcxt_ioctl_blocksize(lc, lc->blocksize)) < 0) {
-               errsv = -rc;
-               goto err;
+               DBG(SETUP, ul_debugobj(lc, "LOOP_CONFIGURE: OK"));
        }
 
-       do {
-               err = ioctl(dev_fd, LOOP_SET_STATUS64, &lc->info);
-               again = err && errno == EAGAIN;
-               if (again)
-                       xusleep(250000);
-       } while (again);
-       if (err) {
-               rc = -errno;
-               errsv = errno;
-               DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64 failed: %m"));
-               goto err;
-       }
+       if (fallback) {
+               /*
+                * Set FD
+                */
+               if (ioctl(dev_fd, LOOP_SET_FD, file_fd) < 0) {
+                       rc = -errno;
+                       errsv = errno;
+                       DBG(SETUP, ul_debugobj(lc, "LOOP_SET_FD failed: %m"));
+                       goto err;
+               }
 
-       DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64: OK"));
+               DBG(SETUP, ul_debugobj(lc, "LOOP_SET_FD: OK"));
+
+               if (lc->blocksize > 0
+                       && (rc = loopcxt_ioctl_blocksize(lc, lc->blocksize)) < 0) {
+                       errsv = -rc;
+                       goto err;
+               }
+
+               do {
+                       err = ioctl(dev_fd, LOOP_SET_STATUS64, &lc->config.info);
+                       again = err && errno == EAGAIN;
+                       if (again)
+                               xusleep(250000);
+               } while (again);
+               if (err) {
+                       rc = -errno;
+                       errsv = errno;
+                       DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64 failed: %m"));
+                       goto err;
+               }
+
+               DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64: OK"));
+       }
 
        if ((rc = loopcxt_check_size(lc, file_fd)))
                goto err;
 
        close(file_fd);
 
-       memset(&lc->info, 0, sizeof(lc->info));
+       memset(&lc->config, 0, sizeof(lc->config));
        lc->has_info = 0;
        lc->info_failed = 0;
 
@@ -1415,7 +1440,7 @@ int loopcxt_ioctl_status(struct loopdev_cxt *lc)
        DBG(SETUP, ul_debugobj(lc, "device open: OK"));
 
        do {
-               err = ioctl(dev_fd, LOOP_SET_STATUS64, &lc->info);
+               err = ioctl(dev_fd, LOOP_SET_STATUS64, &lc->config.info);
                again = err && errno == EAGAIN;
                if (again)
                        xusleep(250000);

diff --git a/sys-utils/losetup.c b/sys-utils/losetup.c
index 379b95f174cf8b6c492968e8815424f1f3c3f5d3..cc4d206b760f46bfcfb3f68b23443c4288e696c9 100644 (file)
--- a/sys-utils/losetup.c
+++ b/sys-utils/losetup.c
@@ -508,7 +508,7 @@ static int create_loop(struct loopdev_cxt *lc,
                                errx(EXIT_FAILURE, _("%s: overlapping encrypted loop device exists"), file);
                        }
 
-                       lc->info.lo_flags &= ~LO_FLAGS_AUTOCLEAR;
+                       lc->config.info.lo_flags &= ~LO_FLAGS_AUTOCLEAR;
                        if (loopcxt_ioctl_status(lc)) {
                                loopcxt_deinit(lc);
                                errx(EXIT_FAILURE, _("%s: failed to re-use loop device"), file);