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Fix bug in vtruncbuf introduced by r346162

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r346162 factored out v_inval_buf_range from vtruncbuf, but it made an error
in the interface between the two.  The result was a failure to remove
buffers past the first.  Surprisingly, I couldn't reproduce the failure with
file systems other than fuse.

Also, modify fusefs's truncate_discards_cached_data test to catch this bug.

PR:		346162
Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Alan Somers 2019-04-23 22:22:46 +00:00
parent 559966d64b
commit 77b8247874
2 changed files with 45 additions and 17 deletions
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2
sys/kern/vfs_subr.c
View File

@ -1883,7 +1883,7 @@ vtruncbuf(struct vnode *vp, struct ucred *cred, off_t length, int blksize)
restart:
bo = &vp->v_bufobj;
BO_LOCK(bo);
if (v_inval_buf_range1(vp, bo, length, INT64_MAX) == EAGAIN)
if (v_inval_buf_range1(vp, bo, startlbn, INT64_MAX) == EAGAIN)
goto restart;
if (length > 0) {

60
tests/sys/fs/fusefs/setattr.cc
View File

@ -350,32 +350,50 @@ TEST_F(Setattr, truncate) {
* Truncating a file should discard cached data past the truncation point.
* This is a regression test for bug 233783. The bug only applies when
* vfs.fusefs.data_cache_mode=1 or 2, but the test should pass regardless.
*
* There are two distinct failure modes. The first one is a failure to zero
* the portion of the file's final buffer past EOF. It can be reproduced by
* fsx -WR -P /tmp -S10 fsx.bin
*
* The second is a failure to drop buffers beyond that. It can be reproduced by
* fsx -WR -P /tmp -S18 -n fsx.bin
* Also reproducible in sh with:
* $> /path/to/libfuse/build/example/passthrough -d /tmp/mnt
* $> cd /tmp/mnt/tmp
* $> dd if=/dev/random of=randfile bs=1k count=192
* $> truncate -s 1k randfile && truncate -s 192k randfile
* $> xxd randfile | less # xxd will wrongly show random data at offset 0x8000
*/
TEST_F(Setattr, truncate_discards_cached_data) {
const char FULLPATH[] = "mountpoint/some_file.txt";
const char RELPATH[] = "some_file.txt";
void *w0buf, *rbuf, *expected;
off_t w0_offset = 0x1b8df;
size_t w0_size = 0x61e8;
off_t r_offset = 0xe1e6;
off_t r_size = 0xe229;
size_t trunc0_size = 0x10016;
size_t trunc1_size = 131072;
void *w0buf, *r0buf, *r1buf, *expected;
off_t w0_offset = 0;
size_t w0_size = 0x30000;
off_t r0_offset = 0;
off_t r0_size = w0_size;
size_t trunc0_size = 0x400;
size_t trunc1_size = w0_size;
off_t r1_offset = trunc0_size;
off_t r1_size = w0_size - trunc0_size;
size_t cur_size = 0;
const uint64_t ino = 42;
mode_t mode = S_IFREG | 0644;
int fd;
int fd, r;
bool should_have_data = false;
w0buf = malloc(w0_size);
ASSERT_NE(NULL, w0buf) << strerror(errno);
memset(w0buf, 'X', w0_size);
rbuf = malloc(r_size);
ASSERT_NE(NULL, rbuf) << strerror(errno);
r0buf = malloc(r0_size);
ASSERT_NE(NULL, r0buf) << strerror(errno);
r1buf = malloc(r1_size);
ASSERT_NE(NULL, r1buf) << strerror(errno);
expected = malloc(r_size);
expected = malloc(r1_size);
ASSERT_NE(NULL, expected) << strerror(errno);
memset(expected, 0, r_size);
memset(expected, 0, r1_size);
expect_lookup(RELPATH, ino, mode, 0, 1);
expect_open(ino, O_RDWR, 1);
@ -435,24 +453,34 @@ TEST_F(Setattr, truncate_discards_cached_data) {
auto osize = std::min(cur_size - in->body.read.offset,
(size_t)in->body.read.size);
out->header.len = sizeof(struct fuse_out_header) + osize;
bzero(out->body.bytes, osize);
if (should_have_data)
memset(out->body.bytes, 'X', osize);
else
bzero(out->body.bytes, osize);
})));
fd = open(FULLPATH, O_RDWR, 0644);
ASSERT_LE(0, fd) << strerror(errno);
/* Fill the file with Xs */
ASSERT_EQ((ssize_t)w0_size, pwrite(fd, w0buf, w0_size, w0_offset));
should_have_data = true;
/* Fill the cache, if data_cache_mode == 1 */
ASSERT_EQ((ssize_t)r0_size, pread(fd, r0buf, r0_size, r0_offset));
/* 1st truncate should discard cached data */
EXPECT_EQ(0, ftruncate(fd, trunc0_size)) << strerror(errno);
should_have_data = false;
/* 2nd truncate extends file into previously cached data */
EXPECT_EQ(0, ftruncate(fd, trunc1_size)) << strerror(errno);
/* Read should return all zeros */
ASSERT_EQ((ssize_t)r_size, pread(fd, rbuf, r_size, r_offset));
ASSERT_EQ((ssize_t)r1_size, pread(fd, r1buf, r1_size, r1_offset));
ASSERT_EQ(0, memcmp(expected, rbuf, r_size));
r = memcmp(expected, r1buf, r1_size);
ASSERT_EQ(0, r);
free(expected);
free(rbuf);
free(r1buf);
free(r0buf);
free(w0buf);
}