devices: reuse bcache fd when getting block size

This avoids an unnecessary open() on the device.

diff --git a/lib/device/dev-io.c b/lib/device/dev-io.c
index dc95131228d665f2b853a9882d67573d752f680a..4460e550acf9aaa4970bdcc9434dca7b3da6cb20 100644 (file)
--- a/lib/device/dev-io.c
+++ b/lib/device/dev-io.c
@@ -148,16 +148,27 @@ static int _io(struct device_area *where, char *buffer, int should_write, dev_io
 int dev_get_block_size(struct device *dev, unsigned int *physical_block_size, unsigned int *block_size)
 {
        const char *name = dev_name(dev);
-       int needs_open;
+       int fd = dev->bcache_fd;
+       int do_close = 0;
        int r = 1;
 
-       needs_open = (!dev->open_count && (dev->phys_block_size == -1 || dev->block_size == -1));
+       if ((dev->phys_block_size > 0) && (dev->block_size > 0)) {
+               *physical_block_size = (unsigned int)dev->phys_block_size;
+               *block_size = (unsigned int)dev->block_size;
+               return 1;
+       }
 
-       if (needs_open && !dev_open_readonly(dev))
-               return_0;
+       if (fd <= 0) {
+               if (!dev->open_count) {
+                       if (!dev_open_readonly(dev))
+                               return_0;
+                       do_close = 1;
+               }
+               fd = dev_fd(dev);
+       }
 
        if (dev->block_size == -1) {
-               if (ioctl(dev_fd(dev), BLKBSZGET, &dev->block_size) < 0) {
+               if (ioctl(fd, BLKBSZGET, &dev->block_size) < 0) {
                        log_sys_error("ioctl BLKBSZGET", name);
                        r = 0;
                        goto out;
@@ -168,7 +179,7 @@ int dev_get_block_size(struct device *dev, unsigned int *physical_block_size, un
 #ifdef BLKPBSZGET
        /* BLKPBSZGET is available in kernel >= 2.6.32 only */
        if (dev->phys_block_size == -1) {
-               if (ioctl(dev_fd(dev), BLKPBSZGET, &dev->phys_block_size) < 0) {
+               if (ioctl(fd, BLKPBSZGET, &dev->phys_block_size) < 0) {
                        log_sys_error("ioctl BLKPBSZGET", name);
                        r = 0;
                        goto out;
@@ -178,7 +189,7 @@ int dev_get_block_size(struct device *dev, unsigned int *physical_block_size, un
 #elif defined (BLKSSZGET)
        /* if we can't get physical block size, just use logical block size instead */
        if (dev->phys_block_size == -1) {
-               if (ioctl(dev_fd(dev), BLKSSZGET, &dev->phys_block_size) < 0) {
+               if (ioctl(fd, BLKSSZGET, &dev->phys_block_size) < 0) {
                        log_sys_error("ioctl BLKSSZGET", name);
                        r = 0;
                        goto out;
@@ -196,7 +207,7 @@ int dev_get_block_size(struct device *dev, unsigned int *physical_block_size, un
        *physical_block_size = (unsigned int) dev->phys_block_size;
        *block_size = (unsigned int) dev->block_size;
 out:
-       if (needs_open && !dev_close_immediate(dev))
+       if (do_close && !dev_close_immediate(dev))
                stack;
 
        return r;