From 53b543476d271cce71c4f5b66d9d6a28f1a75370 Mon Sep 17 00:00:00 2001

From: Karel Zak <kzak@redhat.com>

Date: Wed, 9 Mar 2022 11:28:07 +0100

Subject: lib/loopdev: consolidate ioctls calls on EAGAIN

Keep all logic to repeat ioctl calls in one macro rather than

duplicate code.

Addresses: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=2117203

Signed-off-by: Karel Zak <kzak@redhat.com>

---

 lib/loopdev.c | 97 ++++++++++++++++++++++++++++-----------------------

 1 file changed, 54 insertions(+), 43 deletions(-)

diff --git a/lib/loopdev.c b/lib/loopdev.c

index fda0e1210..cceab2db1 100644

--- a/lib/loopdev.c

+++ b/lib/loopdev.c

@@ -43,7 +43,6 @@

 #include "debug.h"

 #include "fileutils.h"

-

 #define LOOPDEV_MAX_TRIES	10

 /*

@@ -77,6 +76,24 @@ static void loopdev_init_debug(void)

 #define loopcxt_sysfs_available(_lc)	(!((_lc)->flags & LOOPDEV_FL_NOSYSFS)) \

 					 && !loopcxt_ioctl_enabled(_lc)

+/*

+ * Calls @x and repeat on EAGAIN

+ */

+#define repeat_on_eagain(x) __extension__ ({			\

+		int _c = 0, _e;					\

+		do {						\

+			errno = 0;				\

+			_e = x;					\

+			if (_e == 0 || errno != EAGAIN)		\

+				break;				\

+			if (_c >= LOOPDEV_MAX_TRIES)		\

+				break;				\

+			xusleep(250000);			\

+			_c++;					\

+		} while (1);					\

+		_e == 0 ? 0 : errno ? -errno : -1;		\

+	})

+

 /*

  * @lc: context

  * @device: device name, absolute device path or NULL to reset the current setting

@@ -1276,6 +1293,7 @@ static int loopcxt_check_size(struct loopdev_cxt *lc, int file_fd)

 	return 0;

 }

+

 /*

  * @lc: context

  *

@@ -1364,8 +1382,9 @@ int loopcxt_setup_device(struct loopdev_cxt *lc)

 	 * -- since Linux v5.8-rc1, commit 3448914e8cc550ba792d4ccc74471d1ca4293aae

 	 */

 	lc->config.fd = file_fd;

-	if (ioctl(dev_fd, LOOP_CONFIGURE, &lc->config) < 0) {

-		rc = -errno;

+

+	rc = repeat_on_eagain( ioctl(dev_fd, LOOP_CONFIGURE, &lc->config) );

+	if (rc != 0) {

 		errsv = errno;

 		if (errno != EINVAL && errno != ENOTTY) {

 			DBG(SETUP, ul_debugobj(lc, "LOOP_CONFIGURE failed: %m"));

@@ -1430,6 +1449,7 @@ err:

 	return rc;

 }

+

 /*

  * @lc: context

  *

@@ -1443,28 +1463,18 @@ err:

  */

 int loopcxt_ioctl_status(struct loopdev_cxt *lc)

 {

-	int dev_fd, rc = -1, err, again, tries = 0;

+	int dev_fd, rc;

 	errno = 0;

 	dev_fd = loopcxt_get_fd(lc);

-	if (dev_fd < 0) {

-		rc = -errno;

-		return rc;

-	}

-	DBG(SETUP, ul_debugobj(lc, "device open: OK"));

+	if (dev_fd < 0)

+		return -errno;

-	do {

-		err = ioctl(dev_fd, LOOP_SET_STATUS64, &lc->config.info);

-		again = err && errno == EAGAIN;

-		if (again) {

-			xusleep(250000);

-			tries++;

-		}

-	} while (again && tries <= LOOPDEV_MAX_TRIES);

+	DBG(SETUP, ul_debugobj(lc, "calling LOOP_SET_STATUS64"));

-	if (err) {

-		rc = -errno;

+	rc = repeat_on_eagain( ioctl(dev_fd, LOOP_SET_STATUS64, &lc->config.info) );

+	if (rc != 0) {

 		DBG(SETUP, ul_debugobj(lc, "LOOP_SET_STATUS64 failed: %m"));

 		return rc;

 	}

@@ -1475,14 +1485,16 @@ int loopcxt_ioctl_status(struct loopdev_cxt *lc)

 int loopcxt_ioctl_capacity(struct loopdev_cxt *lc)

 {

-	int fd = loopcxt_get_fd(lc);

+	int rc, fd = loopcxt_get_fd(lc);

 	if (fd < 0)

 		return -EINVAL;

+	DBG(SETUP, ul_debugobj(lc, "calling LOOP_SET_CAPACITY"));

+

 	/* Kernels prior to v2.6.30 don't support this ioctl */

-	if (ioctl(fd, LOOP_SET_CAPACITY, 0) < 0) {

-		int rc = -errno;

+	rc = repeat_on_eagain( ioctl(fd, LOOP_SET_CAPACITY, 0) );

+	if (rc != 0) {

 		DBG(CXT, ul_debugobj(lc, "LOOP_SET_CAPACITY failed: %m"));

 		return rc;

 	}

@@ -1493,14 +1505,16 @@ int loopcxt_ioctl_capacity(struct loopdev_cxt *lc)

 int loopcxt_ioctl_dio(struct loopdev_cxt *lc, unsigned long use_dio)

 {

-	int fd = loopcxt_get_fd(lc);

+	int rc, fd = loopcxt_get_fd(lc);

 	if (fd < 0)

 		return -EINVAL;

+	DBG(SETUP, ul_debugobj(lc, "calling LOOP_SET_DIRECT_IO"));

+

 	/* Kernels prior to v4.4 don't support this ioctl */

-	if (ioctl(fd, LOOP_SET_DIRECT_IO, use_dio) < 0) {

-		int rc = -errno;

+	rc = repeat_on_eagain( ioctl(fd, LOOP_SET_DIRECT_IO, use_dio) );

+	if (rc != 0) {

 		DBG(CXT, ul_debugobj(lc, "LOOP_SET_DIRECT_IO failed: %m"));

 		return rc;

 	}

@@ -1515,25 +1529,19 @@ int loopcxt_ioctl_dio(struct loopdev_cxt *lc, unsigned long use_dio)

  */

 int loopcxt_ioctl_blocksize(struct loopdev_cxt *lc, uint64_t blocksize)

 {

-	int fd = loopcxt_get_fd(lc);

-	int err, again, tries = 0;

+	int rc, fd = loopcxt_get_fd(lc);

 	if (fd < 0)

 		return -EINVAL;

-	do {

-		/* Kernels prior to v4.14 don't support this ioctl */

-		err = ioctl(fd, LOOP_SET_BLOCK_SIZE, (unsigned long) blocksize);

-		again = err && errno == EAGAIN;

-		if (again) {

-			xusleep(250000);

-			tries++;

-		} else if (err) {

-			int rc = -errno;

-			DBG(CXT, ul_debugobj(lc, "LOOP_SET_BLOCK_SIZE failed: %m"));

-			return rc;

-		}

-	} while (again && tries <= LOOPDEV_MAX_TRIES);

+	DBG(SETUP, ul_debugobj(lc, "calling LOOP_SET_BLOCK_SIZE"));

+

+	rc = repeat_on_eagain(

+		ioctl(fd, LOOP_SET_BLOCK_SIZE, (unsigned long) blocksize) );

+	if (rc != 0) {

+		DBG(CXT, ul_debugobj(lc, "LOOP_SET_BLOCK_SIZE failed: %m"));

+		return rc;

+	}

 	DBG(CXT, ul_debugobj(lc, "logical block size set"));

 	return 0;

@@ -1541,14 +1549,17 @@ int loopcxt_ioctl_blocksize(struct loopdev_cxt *lc, uint64_t blocksize)

 int loopcxt_delete_device(struct loopdev_cxt *lc)

 {

-	int fd = loopcxt_get_fd(lc);

+	int rc, fd = loopcxt_get_fd(lc);

 	if (fd < 0)

 		return -EINVAL;

-	if (ioctl(fd, LOOP_CLR_FD, 0) < 0) {

+	DBG(SETUP, ul_debugobj(lc, "calling LOOP_SET_CLR_FD"));

+

+	rc = repeat_on_eagain( ioctl(fd, LOOP_CLR_FD, 0) );

+	if (rc != 0) {

 		DBG(CXT, ul_debugobj(lc, "LOOP_CLR_FD failed: %m"));

-		return -errno;

+		return rc;

 	}

 	DBG(CXT, ul_debugobj(lc, "device removed"));

-- 

2.37.1