[PATCH] src/seek_sanity_test: Fix for filesystems without unwritten extent support

[PATCH] src/seek_sanity_test: Fix for filesystems without unwritten extent support

[Andreas Gruenbacher]

src/seek_sanity_test assumes that after preallocating space in a file
with fallocate, fseek SEEK_HOLE / SEEK_DATA will still report the
allocated space as a hole.  On filesystems without unwritten extent
support, that space will be reported as data, though.  On such
filesystems, skip the unwritten extent tests.

Tested on ext4, xfs, and gfs2 + patches for fseek SEEK_HOLE / SEEK_DATA
support.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 src/seek_sanity_test.c | 130 ++++++++++++++++++++++++++-----------------------
 1 file changed, 69 insertions(+), 61 deletions(-)

diff --git a/src/seek_sanity_test.c b/src/seek_sanity_test.c
index 95984b6..a58ec36 100644
--- a/src/seek_sanity_test.c
+++ b/src/seek_sanity_test.c
@@ -37,6 +37,7 @@
 
 static blksize_t alloc_size;
 int default_behavior = 0;
+int unwritten_extents = 0;
 char *base_file_path;
 
 static void get_file_system(int fd)
@@ -128,13 +129,9 @@ static int do_fallocate(int fd, off_t offset, off_t length, int mode)
 	int ret;
 
 	ret = fallocate(fd, mode, offset, length);
-	if (ret) {
-		/* Don't warn about a filesystem w/o fallocate support */
-		if (errno == EOPNOTSUPP)
-			return ret;
+	if (ret)
 		fprintf(stderr, "  ERROR %d: Failed to preallocate "
 			"space to %ld bytes\n", errno, (long) length);
-	}
 
 	return ret;
 }
@@ -284,6 +281,11 @@ static int test17(int fd, int testnum)
 	int bufsz, filsz;
 	int ret = 0;
 
+	if (!unwritten_extents) {
+		fprintf(stdout, "Test skipped as fs doesn't support unwritten extents.\n");
+		goto out;
+	}
+
 	if (pagesz < 4 * alloc_size) {
 		fprintf(stdout, "Test skipped as page size (%d) is less than "
 			"four times allocation size (%d).\n",
@@ -301,14 +303,8 @@ static int test17(int fd, int testnum)
 	memset(buf, 'a', bufsz);
 
 	ret = do_fallocate(fd, 0, filsz, 0);
-	if (ret < 0) {
-		/* Report success if fs doesn't support fallocate */
-		if (errno == EOPNOTSUPP) {
-			fprintf(stdout, "Test skipped as fs doesn't support fallocate.\n");
-			ret = 0;
-		}
+	if (ret < 0)
 		goto out;
-	}
 
 	ret = do_pwrite(fd, buf, bufsz, 0);
 	if (ret)
@@ -355,6 +351,11 @@ static int test16(int fd, int testnum)
 	int bufsz = sysconf(_SC_PAGE_SIZE);
 	int filsz = 4 << 20;
 
+	if (!unwritten_extents) {
+		fprintf(stdout, "Test skipped as fs doesn't support unwritten extents.\n");
+		goto out;
+	}
+
 	/* HOLE - unwritten DATA in dirty page */
 	/* Each unit is bufsz */
 	buf = do_malloc(bufsz);
@@ -364,14 +365,8 @@ static int test16(int fd, int testnum)
 
 	/* preallocate 4M space to file */
 	ret = do_fallocate(fd, 0, filsz, 0);
-	if (ret < 0) {
-		/* Report success if fs doesn't support fallocate */
-		if (errno == EOPNOTSUPP) {
-			fprintf(stdout, "Test skipped as fs doesn't support fallocate.\n");
-			ret = 0;
-		}
+	if (ret < 0)
 		goto out;
-	}
 
 	ret = do_pwrite(fd, buf, bufsz, 0);
 	if (ret)
@@ -406,6 +401,11 @@ static int test15(int fd, int testnum)
 	int bufsz = sysconf(_SC_PAGE_SIZE);
 	int filsz = 4 << 20;
 
+	if (!unwritten_extents) {
+		fprintf(stdout, "Test skipped as fs doesn't support unwritten extents.\n");
+		goto out;
+	}
+
 	/* HOLE - unwritten DATA in dirty page */
 	/* Each unit is bufsz */
 	buf = do_malloc(bufsz);
@@ -415,14 +415,8 @@ static int test15(int fd, int testnum)
 
 	/* preallocate 4M space to file */
 	ret = do_fallocate(fd, 0, filsz, 0);
-	if (ret < 0) {
-		/* Report success if fs doesn't support fallocate */
-		if (errno == EOPNOTSUPP) {
-			fprintf(stdout, "Test skipped as fs doesn't support fallocate.\n");
-			ret = 0;
-		}
+	if (ret < 0)
 		goto out;
-	}
 
 	ret = do_pwrite(fd, buf, bufsz, 0);
 	if (ret)
@@ -459,6 +453,11 @@ static int test14(int fd, int testnum)
 	int bufsz = sysconf(_SC_PAGE_SIZE) * 14;
 	int filsz = 4 << 20;
 
+	if (!unwritten_extents) {
+		fprintf(stdout, "Test skipped as fs doesn't support unwritten extents.\n");
+		goto out;
+	}
+
 	/* HOLE - unwritten DATA in dirty page */
 	/* Each unit is bufsz */
 	buf = do_malloc(bufsz);
@@ -468,14 +467,8 @@ static int test14(int fd, int testnum)
 
 	/* preallocate 4M space to file */
 	ret = do_fallocate(fd, 0, filsz, 0);
-	if (ret < 0) {
-		/* Report success if fs doesn't support fallocate */
-		if (errno == EOPNOTSUPP) {
-			fprintf(stdout, "Test skipped as fs doesn't support fallocate.\n");
-			ret = 0;
-		}
+	if (ret < 0)
 		goto out;
-	}
 
 	ret = do_pwrite(fd, buf, bufsz, 0);
 	if (ret)
@@ -509,6 +502,11 @@ static int test13(int fd, int testnum)
 	int bufsz = sysconf(_SC_PAGE_SIZE) * 14;
 	int filsz = 4 << 20;
 
+	if (!unwritten_extents) {
+		fprintf(stdout, "Test skipped as fs doesn't support unwritten extents.\n");
+		goto out;
+	}
+
 	/* HOLE - unwritten DATA in dirty page */
 	/* Each unit is bufsz */
 	buf = do_malloc(bufsz);
@@ -518,14 +516,8 @@ static int test13(int fd, int testnum)
 
 	/* preallocate 4M space to file */
 	ret = do_fallocate(fd, 0, filsz, 0);
-	if (ret < 0) {
-		/* Report success if fs doesn't support fallocate */
-		if (errno == EOPNOTSUPP) {
-			fprintf(stdout, "Test skipped as fs doesn't support fallocate.\n");
-			ret = 0;
-		}
+	if (ret < 0)
 		goto out;
-	}
 
 	ret = do_pwrite(fd, buf, bufsz, 0);
 	if (ret)
@@ -579,6 +571,11 @@ static int test09(int fd, int testnum)
 	int bufsz = alloc_size;
 	int filsz = bufsz * 100 + bufsz;
 
+	if (!unwritten_extents) {
+		fprintf(stdout, "Test skipped as fs doesn't support unwritten extents.\n");
+		goto out;
+	}
+
 	/*
 	 * HOLE - unwritten DATA in dirty page - HOLE -
 	 * unwritten DATA in writeback page
@@ -592,14 +589,8 @@ static int test09(int fd, int testnum)
 
 	/* preallocate 8M space to file */
 	ret = do_fallocate(fd, 0, filsz, 0);
-	if (ret < 0) {
-		/* Report success if fs doesn't support fallocate */
-		if (errno == EOPNOTSUPP) {
-			fprintf(stdout, "Test skipped as fs doesn't support fallocate.\n");
-			ret = 0;
-		}
+	if (ret < 0)
 		goto out;
-	}
 
 	ret = do_pwrite(fd, buf, bufsz, bufsz * 10);
 	if (!ret) {
@@ -635,6 +626,11 @@ static int test08(int fd, int testnum)
 	int bufsz = alloc_size;
 	int filsz = bufsz * 10 + bufsz;
 
+	if (!unwritten_extents) {
+		fprintf(stdout, "Test skipped as fs doesn't support unwritten extents.\n");
+		goto out;
+	}
+
 	/* HOLE - unwritten DATA in writeback page */
 	/* Each unit is bufsz */
 	buf = do_malloc(bufsz);
@@ -644,14 +640,8 @@ static int test08(int fd, int testnum)
 
 	/* preallocate 4M space to file */
 	ret = do_fallocate(fd, 0, filsz, 0);
-	if (ret < 0) {
-		/* Report success if fs doesn't support fallocate */
-		if (errno == EOPNOTSUPP) {
-			fprintf(stdout, "Test skipped as fs doesn't support fallocate.\n");
-			ret = 0;
-		}
+	if (ret < 0)
 		goto out;
-	}
 
 	ret = do_pwrite(fd, buf, bufsz, bufsz * 10);
 	if (ret)
@@ -684,6 +674,11 @@ static int test07(int fd, int testnum)
 	int bufsz = alloc_size;
 	int filsz = bufsz * 10 + bufsz;
 
+	if (!unwritten_extents) {
+		fprintf(stdout, "Test skipped as fs doesn't support unwritten extents.\n");
+		goto out;
+	}
+
 	/* HOLE - unwritten DATA in dirty page */
 	/* Each unit is bufsz */
 	buf = do_malloc(bufsz);
@@ -693,14 +688,8 @@ static int test07(int fd, int testnum)
 
 	/* preallocate 4M space to file */
 	ret = do_fallocate(fd, 0, filsz, 0);
-	if (ret < 0) {
-		/* Report success if fs doesn't support fallocate */
-		if (errno == EOPNOTSUPP) {
-			fprintf(stdout, "Test skipped as fs doesn't support fallocate.\n");
-			ret = 0;
-		}
+	if (ret < 0)
 		goto out;
-	}
 
 	ret = do_pwrite(fd, buf, bufsz, bufsz * 10);
 	if (ret)
@@ -1050,6 +1039,25 @@ static int test_basic_support(void)
 		fprintf(stderr, "File system supports the default behavior.\n");
 	}
 
+	ftruncate(fd, 0);
+	if (fallocate(fd, 0, 0, alloc_size) == -1) {
+		if (errno == EOPNOTSUPP)
+			fprintf(stderr, "File system does not support fallocate.");
+		else {
+			fprintf(stderr, "ERROR %d: Failed to preallocate "
+				"space to %ld bytes. Aborting.\n", errno, (long) alloc_size);
+			ret = -1;
+		}
+		goto out;
+	}
+
+	pos = lseek(fd, 0, SEEK_DATA);
+	if (pos == 0) {
+		fprintf(stderr, "File system does not support unwritten extents.\n");
+		goto out;
+	}
+	unwritten_extents = 1;
+
 	printf("\n");
 
 out:
-- 
2.7.5

Re: [PATCH] src/seek_sanity_test: Fix for filesystems without unwritten extent support

[Andreas Gruenbacher]

On Fri, May 12, 2017 at 7:09 AM, Eryu Guan <eguan@redhat.com> wrote:
> On Thu, May 11, 2017 at 01:35:07PM +0200, Andreas Gruenbacher wrote:
>> src/seek_sanity_test (test generic/285) assumes that after preallocating
>> space in a file with fallocate, fseek SEEK_HOLE / SEEK_DATA will still
>> report the allocated space as a hole.  On filesystems without unwritten
>> extent support, that space will be reported as data, though.
>>
>> Tested on ext4, xfs, and gfs2 + patches for fseek SEEK_HOLE / SEEK_DATA
>> support.
>
> The idea seems fine to me, but I'm not that familiar with SEEK_DATA/HOLE
> support, it'd be great if someone else could help review this patch.
>
> Some of my thoughts inline.
>
>>
>> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
>> ---
>>  src/seek_sanity_test.c | 35 +++++++++++++++++++++++++++++++++++
>>  1 file changed, 35 insertions(+)
>>
>> diff --git a/src/seek_sanity_test.c b/src/seek_sanity_test.c
>> index a6dd48c..0d7fa0a 100644
>> --- a/src/seek_sanity_test.c
>> +++ b/src/seek_sanity_test.c
>> @@ -37,6 +37,7 @@
>>
>>  static blksize_t alloc_size;
>>  int default_behavior = 0;
>> +int unwritten_extents = 0;
>>  char *base_file_path;
>>
>>  static void get_file_system(int fd)
>> @@ -282,6 +283,11 @@ static int test09(int fd, int testnum)
>>       int bufsz = alloc_size;
>>       int filsz = 8 << 20;
>>
>> +     if (!unwritten_extents) {
>> +             fprintf(stdout, "Test skipped\n");
>> +             goto out;
>> +     }
>> +
>>       /*
>>        * HOLE - unwritten DATA in dirty page - HOLE -
>>        * unwritten DATA in writeback page
>> @@ -338,6 +344,11 @@ static int test08(int fd, int testnum)
>>       int bufsz = alloc_size;
>>       int filsz = 4 << 20;
>>
>> +     if (!unwritten_extents) {
>> +             fprintf(stdout, "Test skipped\n");
>> +             goto out;
>> +     }
>> +
>>       /* HOLE - unwritten DATA in writeback page */
>>       /* Each unit is bufsz */
>>       buf = do_malloc(bufsz);
>> @@ -387,6 +398,11 @@ static int test07(int fd, int testnum)
>>       int bufsz = alloc_size;
>>       int filsz = 4 << 20;
>>
>> +     if (!unwritten_extents) {
>> +             fprintf(stdout, "Test skipped\n");
>> +             goto out;
>> +     }
>> +
>>       /* HOLE - unwritten DATA in dirty page */
>>       /* Each unit is bufsz */
>>       buf = do_malloc(bufsz);
>> @@ -776,6 +792,25 @@ static int test_basic_support(void)
>>               fprintf(stderr, "File system supports the default behavior.\n");
>>       }
>>
>> +     ftruncate(fd, 0);
>> +     if (fallocate(fd, 0, 0, alloc_size) == -1) {
>> +             if (errno == EOPNOTSUPP) {
>> +                     fprintf(stderr, "File system does not support fallocate.");
>> +             } else {
>> +                     fprintf(stderr, "ERROR %d: Failed to preallocate "
>> +                             "space to %ld bytes.", errno, (long) alloc_size);
>> +             }
>
> Use do_fallocate here? It already did the EOPNOTSUPP check. And
> introduce another flag, e.g. prealloc, to save the fallocate support
> status? So that test0[7-9] don't have to do the EOPNOTSUPP check again.

In fact unwritten extent support implies fallocate support, so we can
get rid of the redundant checks for missing fallocate support.

>> +             fprintf(stderr, "  Skipping unwritten extent tests.\n");
>> +             goto out;
>> +     } else {
>> +             pos = lseek(fd, 0, SEEK_DATA);
>
> Hmm, it's hard to tell if it's a bug in lseek or the fs doesn't support
> unwritten extents, because we're going to test lseek SEEK_DATA/HOLE
> interface.
>
> How about using fiemap and check the FIEMAP_EXTENT_UNWRITTEN flag? Only
> falling back to lseek if fiemap is not supported?

Wouldn't this only complicate and open things up to fiemap bugs in addition?

I'll send an updated patch.

Thanks,
Andreas

Re: [PATCH] src/seek_sanity_test: Fix for filesystems without unwritten extent support

[Eryu Guan]

On Thu, May 11, 2017 at 01:35:07PM +0200, Andreas Gruenbacher wrote:
> src/seek_sanity_test (test generic/285) assumes that after preallocating
> space in a file with fallocate, fseek SEEK_HOLE / SEEK_DATA will still
> report the allocated space as a hole.  On filesystems without unwritten
> extent support, that space will be reported as data, though.
> 
> Tested on ext4, xfs, and gfs2 + patches for fseek SEEK_HOLE / SEEK_DATA
> support.

The idea seems fine to me, but I'm not that familiar with SEEK_DATA/HOLE
support, it'd be great if someone else could help review this patch.

Some of my thoughts inline.

> 
> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
> ---
>  src/seek_sanity_test.c | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
> 
> diff --git a/src/seek_sanity_test.c b/src/seek_sanity_test.c
> index a6dd48c..0d7fa0a 100644
> --- a/src/seek_sanity_test.c
> +++ b/src/seek_sanity_test.c
> @@ -37,6 +37,7 @@
>  
>  static blksize_t alloc_size;
>  int default_behavior = 0;
> +int unwritten_extents = 0;
>  char *base_file_path;
>  
>  static void get_file_system(int fd)
> @@ -282,6 +283,11 @@ static int test09(int fd, int testnum)
>  	int bufsz = alloc_size;
>  	int filsz = 8 << 20;
>  
> +	if (!unwritten_extents) {
> +		fprintf(stdout, "Test skipped\n");
> +		goto out;
> +	}
> +
>  	/*
>  	 * HOLE - unwritten DATA in dirty page - HOLE -
>  	 * unwritten DATA in writeback page
> @@ -338,6 +344,11 @@ static int test08(int fd, int testnum)
>  	int bufsz = alloc_size;
>  	int filsz = 4 << 20;
>  
> +	if (!unwritten_extents) {
> +		fprintf(stdout, "Test skipped\n");
> +		goto out;
> +	}
> +
>  	/* HOLE - unwritten DATA in writeback page */
>  	/* Each unit is bufsz */
>  	buf = do_malloc(bufsz);
> @@ -387,6 +398,11 @@ static int test07(int fd, int testnum)
>  	int bufsz = alloc_size;
>  	int filsz = 4 << 20;
>  
> +	if (!unwritten_extents) {
> +		fprintf(stdout, "Test skipped\n");
> +		goto out;
> +	}
> +
>  	/* HOLE - unwritten DATA in dirty page */
>  	/* Each unit is bufsz */
>  	buf = do_malloc(bufsz);
> @@ -776,6 +792,25 @@ static int test_basic_support(void)
>  		fprintf(stderr, "File system supports the default behavior.\n");
>  	}
>  
> +	ftruncate(fd, 0);
> +	if (fallocate(fd, 0, 0, alloc_size) == -1) {
> +		if (errno == EOPNOTSUPP) {
> +			fprintf(stderr, "File system does not support fallocate.");
> +		} else {
> +			fprintf(stderr, "ERROR %d: Failed to preallocate "
> +				"space to %ld bytes.", errno, (long) alloc_size);
> +		}

Use do_fallocate here? It already did the EOPNOTSUPP check. And
introduce another flag, e.g. prealloc, to save the fallocate support
status? So that test0[7-9] don't have to do the EOPNOTSUPP check again.

> +		fprintf(stderr, "  Skipping unwritten extent tests.\n");
> +		goto out;
> +	} else {
> +		pos = lseek(fd, 0, SEEK_DATA);

Hmm, it's hard to tell if it's a bug in lseek or the fs doesn't support
unwritten extents, because we're going to test lseek SEEK_DATA/HOLE
interface.

How about using fiemap and check the FIEMAP_EXTENT_UNWRITTEN flag? Only
falling back to lseek if fiemap is not supported?

Thanks,
Eryu

> +		if (pos == 0) {
> +			fprintf(stderr, "File system does not support unwritten extents.\n");
> +			goto out;
> +		}
> +	}
> +	unwritten_extents = 1;
> +
>  	printf("\n");
>  
>  out:
> -- 
> 2.7.4
> 
> --
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[PATCH] src/seek_sanity_test: Fix for filesystems without unwritten extent support

[Andreas Gruenbacher]

src/seek_sanity_test (test generic/285) assumes that after preallocating
space in a file with fallocate, fseek SEEK_HOLE / SEEK_DATA will still
report the allocated space as a hole.  On filesystems without unwritten
extent support, that space will be reported as data, though.

Tested on ext4, xfs, and gfs2 + patches for fseek SEEK_HOLE / SEEK_DATA
support.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 src/seek_sanity_test.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/src/seek_sanity_test.c b/src/seek_sanity_test.c
index a6dd48c..0d7fa0a 100644
--- a/src/seek_sanity_test.c
+++ b/src/seek_sanity_test.c
@@ -37,6 +37,7 @@
 
 static blksize_t alloc_size;
 int default_behavior = 0;
+int unwritten_extents = 0;
 char *base_file_path;
 
 static void get_file_system(int fd)
@@ -282,6 +283,11 @@ static int test09(int fd, int testnum)
 	int bufsz = alloc_size;
 	int filsz = 8 << 20;
 
+	if (!unwritten_extents) {
+		fprintf(stdout, "Test skipped\n");
+		goto out;
+	}
+
 	/*
 	 * HOLE - unwritten DATA in dirty page - HOLE -
 	 * unwritten DATA in writeback page
@@ -338,6 +344,11 @@ static int test08(int fd, int testnum)
 	int bufsz = alloc_size;
 	int filsz = 4 << 20;
 
+	if (!unwritten_extents) {
+		fprintf(stdout, "Test skipped\n");
+		goto out;
+	}
+
 	/* HOLE - unwritten DATA in writeback page */
 	/* Each unit is bufsz */
 	buf = do_malloc(bufsz);
@@ -387,6 +398,11 @@ static int test07(int fd, int testnum)
 	int bufsz = alloc_size;
 	int filsz = 4 << 20;
 
+	if (!unwritten_extents) {
+		fprintf(stdout, "Test skipped\n");
+		goto out;
+	}
+
 	/* HOLE - unwritten DATA in dirty page */
 	/* Each unit is bufsz */
 	buf = do_malloc(bufsz);
@@ -776,6 +792,25 @@ static int test_basic_support(void)
 		fprintf(stderr, "File system supports the default behavior.\n");
 	}
 
+	ftruncate(fd, 0);
+	if (fallocate(fd, 0, 0, alloc_size) == -1) {
+		if (errno == EOPNOTSUPP) {
+			fprintf(stderr, "File system does not support fallocate.");
+		} else {
+			fprintf(stderr, "ERROR %d: Failed to preallocate "
+				"space to %ld bytes.", errno, (long) alloc_size);
+		}
+		fprintf(stderr, "  Skipping unwritten extent tests.\n");
+		goto out;
+	} else {
+		pos = lseek(fd, 0, SEEK_DATA);
+		if (pos == 0) {
+			fprintf(stderr, "File system does not support unwritten extents.\n");
+			goto out;
+		}
+	}
+	unwritten_extents = 1;
+
 	printf("\n");
 
 out:
-- 
2.7.4