From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stanislav Kholmanskikh Date: Fri, 26 Aug 2016 14:17:53 +0300 Subject: [LTP] [PATCH] syscalls/fallocate04: Fix on Btrfs In-Reply-To: <20160825165354.GA13281@rei> References: <20160825165354.GA13281@rei> Message-ID: <57C02561.8000608@oracle.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ltp@lists.linux.it Hi, On 08/25/2016 07:53 PM, Cyril Hrubis wrote: > The size of a file can double on Btrfs temporarily even when we write > into a preallocated space because of internal Btrfs caches, at least > that is what I've been told by Btrfs devs. The internal caches are then > freed after some time, or can be force freed by syncing the file, which > is what this patch does. > > Technically we are not guaranteed that the file size will not change after > writing to preallocated space. We are only guaranteed that subsequent writes to > the region will not fail with ENOSPC. So this behavior, while uncommon, is not > really a bug. > > Before the patch the test fails with: > > fallocate04 0 TINFO : allocate '12288' bytes > fallocate04 1 TPASS : test-case succeeded > fallocate04 0 TINFO : read allocated file size '24576' > fallocate04 0 TINFO : make a hole with FALLOC_FL_PUNCH_HOLE > fallocate04 0 TINFO : check that file has a hole with lseek(,,SEEK_HOLE) > fallocate04 0 TINFO : found a hole at '4096' offset > fallocate04 0 TINFO : allocated file size before '24576' and after '12288' > fallocate04 2 TFAIL : fallocate04.c:184: not expected allocated size > Tested this on SPARC: * without the patch a 2.6.39-based kernel: [root@skholman-m7 fallocate]# TMPDIR=/mnt ./fallocate04 fallocate04 0 TINFO : allocate '24576' bytes fallocate04 1 TPASS : test-case succeeded fallocate04 0 TINFO : read allocated file size '49152' fallocate04 0 TINFO : make a hole with FALLOC_FL_PUNCH_HOLE fallocate04 0 TINFO : check that file has a hole with lseek(,,SEEK_HOLE) fallocate04 0 TINFO : lseek() doesn't support SEEK_HOLE, this is expected for < 3.1 kernels fallocate04 0 TINFO : allocated file size before '49152' and after '24576' fallocate04 2 TFAIL : fallocate04.c:184: not expected allocated size [root@skholman-m7 fallocate]# a 4.1-based kernel: [root@skholman-m7 fallocate]# TMPDIR=/mnt ./fallocate04 fallocate04 0 TINFO : allocate '24576' bytes fallocate04 1 TPASS : test-case succeeded fallocate04 0 TINFO : read allocated file size '49152' fallocate04 0 TINFO : make a hole with FALLOC_FL_PUNCH_HOLE fallocate04 0 TINFO : check that file has a hole with lseek(,,SEEK_HOLE) fallocate04 0 TINFO : found a hole at '8192' offset fallocate04 0 TINFO : allocated file size before '49152' and after '24576' fallocate04 2 TFAIL : fallocate04.c:184: not expected allocated size [root@skholman-m7 fallocate]# * with your patch a 2.6.39-based kernel: [root@skholman-m7 fallocate]# TMPDIR=/mnt ./fallocate04 fallocate04 0 TINFO : allocate '24576' bytes fallocate04 1 TPASS : test-case succeeded fallocate04 0 TINFO : read allocated file size '24576' fallocate04 0 TINFO : make a hole with FALLOC_FL_PUNCH_HOLE fallocate04 0 TINFO : check that file has a hole with lseek(,,SEEK_HOLE) fallocate04 0 TINFO : lseek() doesn't support SEEK_HOLE, this is expected for < 3.1 kernels fallocate04 0 TINFO : allocated file size before '24576' and after '16384' fallocate04 0 TINFO : reading the file, compare with expected buffer fallocate04 2 TPASS : test-case succeeded fallocate04 0 TINFO : zeroing file space with FALLOC_FL_ZERO_RANGE fallocate04 3 TCONF : fallocate04.c:204: FALLOC_FL_ZERO_RANGE needs Linux 3.15 or newer fallocate04 4 TCONF : fallocate04.c:204: Remaining cases not appropriate for configuration [root@skholman-m7 fallocate]# a 4.1-based kernel: [root@skholman-m7 fallocate]# TMPDIR=/mnt ./fallocate04 fallocate04 0 TINFO : allocate '24576' bytes fallocate04 1 TPASS : test-case succeeded fallocate04 0 TINFO : read allocated file size '24576' fallocate04 0 TINFO : make a hole with FALLOC_FL_PUNCH_HOLE fallocate04 0 TINFO : check that file has a hole with lseek(,,SEEK_HOLE) fallocate04 0 TINFO : found a hole@'8192' offset fallocate04 0 TINFO : allocated file size before '24576' and after '16384' fallocate04 0 TINFO : reading the file, compare with expected buffer fallocate04 2 TPASS : test-case succeeded fallocate04 0 TINFO : zeroing file space with FALLOC_FL_ZERO_RANGE fallocate04 0 TINFO : read current allocated file size '16384' fallocate04 3 TCONF : fallocate04.c:215: FALLOC_FL_ZERO_RANGE not supported fallocate04 4 TCONF : fallocate04.c:215: Remaining cases not appropriate for configuration [root@skholman-m7 fallocate]# Thanks for solving this problem. > Signed-off-by: Cyril Hrubis > --- > testcases/kernel/syscalls/fallocate/fallocate04.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/testcases/kernel/syscalls/fallocate/fallocate04.c b/testcases/kernel/syscalls/fallocate/fallocate04.c > index 2b904e4..f204188 100644 > --- a/testcases/kernel/syscalls/fallocate/fallocate04.c > +++ b/testcases/kernel/syscalls/fallocate/fallocate04.c > @@ -75,6 +75,8 @@ static size_t get_allocsize(void) > { > struct stat file_stat; > > + fsync(fd); > + > SAFE_FSTAT(cleanup, fd, &file_stat); > > return file_stat.st_blocks * 512; >