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src/fiemap-tester: fix getting blocksize on overlayfs

PATCH New Amir Goldstein 1 participant 1 message Oct 11, 2018

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Amir Goldstein

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PATCH v2 1/1 src/fiemap-tester: fix getting blocksize on overlayfs

There was a regression in v4.19-rc1 that caused FIGETBSZ ioctl to return 0 on an overlayfs file.

That regression went unnoticed because the xfstests that run fiemap-tester program terminated in success status after not doing much instead of failing.

Check for invalid value of block size returned by FIGETBSZ ioctl, so these tests can detect the regression.

Fallback to statfs(2) for getting the filesystem blocksize if FIGETBSZ ioctl fails (i.e. on overlayfs).

Signed-off-by Amir Goldstein <[email protected]>
---
 src/fiemap-tester.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)
src/fiemap-tester.c +14 -1
index 97ac5ad0..3db24daa 100644
@@ -14,6 +14,7 @@
 #include <sys/ioctl.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/statfs.h>
 #include <sys/vfs.h>
 #include <linux/fs.h>
 #include <linux/types.h>

@@ -556,7 +557,19 @@ main(int argc, char **argv)
 	}
 
 	if (ioctl(fd, FIGETBSZ, &blocksize) < 0) {
-		perror("Can't get filesystem block size");
+		struct statfs buf;
+
+		if (fstatfs(fd, &buf) == 0) {
+			blocksize = buf.f_bsize;
+		} else {
+			perror("Can't get filesystem block size");
+			close(fd);
+			exit(1);
+		}
+	}
+
+	if (blocksize <= 0) {
+		printf("Illegal filesystem block size\n");
 		close(fd);
 		exit(1);
 	}
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