git: 032a5bd55b3a - main - fusefs: Fix a bug during VOP_STRATEGY when the server changes file size
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Date: Wed, 06 Oct 2021 20:08:01 UTC
The branch main has been updated by asomers: URL: https://cgit.FreeBSD.org/src/commit/?id=032a5bd55b3a003d3560435422a95f27f91685fe commit 032a5bd55b3a003d3560435422a95f27f91685fe Author: Alan Somers <asomers@FreeBSD.org> AuthorDate: 2021-10-03 17:51:14 +0000 Commit: Alan Somers <asomers@FreeBSD.org> CommitDate: 2021-10-06 20:07:33 +0000 fusefs: Fix a bug during VOP_STRATEGY when the server changes file size If the FUSE server tells the kernel that a file's size has changed, then the kernel must invalidate any portion of that file in cache. But the kernel can't do that during VOP_STRATEGY, because the file's buffers are already locked. Instead, proceed with the write. PR: 256937 Reported by: Agata <chogata@moosefs.pro> Tested by: Agata <chogata@moosefs.pro> MFC after: 2 weeks Reviewed by: pfg Differential Revision: https://reviews.freebsd.org/D32332 --- sys/fs/fuse/fuse_io.c | 19 +++++++---- tests/sys/fs/fusefs/write.cc | 81 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 93 insertions(+), 7 deletions(-) diff --git a/sys/fs/fuse/fuse_io.c b/sys/fs/fuse/fuse_io.c index 637c36424d3f..f818fbd52869 100644 --- a/sys/fs/fuse/fuse_io.c +++ b/sys/fs/fuse/fuse_io.c @@ -1007,13 +1007,18 @@ fuse_io_strategy(struct vnode *vp, struct buf *bp) /* * Setup for actual write */ - error = fuse_vnode_size(vp, &filesize, cred, curthread); - if (error) { - bp->b_ioflags |= BIO_ERROR; - bp->b_error = error; - bufdone(bp); - return (error); - } + /* + * If the file's size is cached, use that value, even if the + * cache is expired. At this point we're already committed to + * writing something. If the FUSE server has changed the + * file's size behind our back, it's too late for us to do + * anything about it. In particular, we can't invalidate any + * part of the file's buffers because VOP_STRATEGY is called + * with them already locked. + */ + filesize = fvdat->cached_attrs.va_size; + /* filesize must've been cached by fuse_vnop_open. */ + KASSERT(filesize != VNOVAL, ("filesize should've been cached")); if ((off_t)bp->b_lblkno * biosize + bp->b_dirtyend > filesize) bp->b_dirtyend = filesize - diff --git a/tests/sys/fs/fusefs/write.cc b/tests/sys/fs/fusefs/write.cc index fadf4648d31c..db5bb3fe4441 100644 --- a/tests/sys/fs/fusefs/write.cc +++ b/tests/sys/fs/fusefs/write.cc @@ -208,6 +208,9 @@ virtual void SetUp() { } }; +class WriteEofDuringVnopStrategy: public Write, public WithParamInterface<int> +{}; + void sigxfsz_handler(int __unused sig) { Write::s_sigxfsz = 1; } @@ -526,6 +529,84 @@ TEST_F(Write, eof_during_rmw) leak(fd); } +/* + * VOP_STRATEGY should not query the server for the file's size, even if its + * cached attributes have expired. + * Regression test for https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=256937 + */ +TEST_P(WriteEofDuringVnopStrategy, eof_during_vop_strategy) +{ + const char FULLPATH[] = "mountpoint/some_file.txt"; + const char RELPATH[] = "some_file.txt"; + Sequence seq; + const off_t filesize = 2 * m_maxbcachebuf; + void *contents; + uint64_t ino = 42; + uint64_t attr_valid = 0; + uint64_t attr_valid_nsec = 0; + mode_t mode = S_IFREG | 0644; + int fd; + int ngetattrs; + + ngetattrs = GetParam(); + contents = calloc(1, filesize); + + EXPECT_LOOKUP(FUSE_ROOT_ID, RELPATH) + .WillRepeatedly(Invoke( + ReturnImmediate([=](auto in __unused, auto& out) { + SET_OUT_HEADER_LEN(out, entry); + out.body.entry.attr.mode = mode; + out.body.entry.nodeid = ino; + out.body.entry.attr.nlink = 1; + out.body.entry.attr.size = filesize; + out.body.entry.attr_valid = attr_valid; + out.body.entry.attr_valid_nsec = attr_valid_nsec; + }))); + expect_open(ino, 0, 1); + EXPECT_CALL(*m_mock, process( + ResultOf([=](auto in) { + return (in.header.opcode == FUSE_GETATTR && + in.header.nodeid == ino); + }, Eq(true)), + _) + ).Times(Between(ngetattrs - 1, ngetattrs)) + .InSequence(seq) + .WillRepeatedly(Invoke(ReturnImmediate([=](auto i __unused, auto& out) { + SET_OUT_HEADER_LEN(out, attr); + out.body.attr.attr.ino = ino; + out.body.attr.attr.mode = mode; + out.body.attr.attr_valid = attr_valid; + out.body.attr.attr_valid_nsec = attr_valid_nsec; + out.body.attr.attr.size = filesize; + }))); + EXPECT_CALL(*m_mock, process( + ResultOf([=](auto in) { + return (in.header.opcode == FUSE_GETATTR && + in.header.nodeid == ino); + }, Eq(true)), + _) + ).InSequence(seq) + .WillRepeatedly(Invoke(ReturnImmediate([=](auto i __unused, auto& out) { + SET_OUT_HEADER_LEN(out, attr); + out.body.attr.attr.ino = ino; + out.body.attr.attr.mode = mode; + out.body.attr.attr_valid = attr_valid; + out.body.attr.attr_valid_nsec = attr_valid_nsec; + out.body.attr.attr.size = filesize / 2; + }))); + expect_write(ino, 0, filesize / 2, filesize / 2, contents); + + fd = open(FULLPATH, O_RDWR); + ASSERT_LE(0, fd) << strerror(errno); + ASSERT_EQ(filesize / 2, write(fd, contents, filesize / 2)) + << strerror(errno); + +} + +INSTANTIATE_TEST_CASE_P(W, WriteEofDuringVnopStrategy, + Values(1, 2, 3) +); + /* * If the kernel cannot be sure which uid, gid, or pid was responsible for a * write, then it must set the FUSE_WRITE_CACHE bit