From 8adbc60284ee6636912368c68bea3f94829e6992 Mon Sep 17 00:00:00 2001 From: Bernd Schubert Date: Mon, 7 Apr 2025 11:50:19 +0200 Subject: fuse_lowlevel: Set bufsize if HAVE_SPLICE is not define and avoid race These are several buf size fixes 1) Set bufsize when HAVE_SPLICE is not defined. Addresses https://github.com/libfuse/libfuse/issues/1184 2) Check in the read retry condition for bufsize, i.e. the value passed to read and not for the buf->mem_size. Using buf->mem_size can be startup racy. Additionally we now also set bufsize on allocation to avoid these races. 3) Allocation and value assigned needs to follow the pattern bufsize = se->bufsize; buf_alloc(bufsize, internal) buf->mem_size = bufsize; I.e. bufsize has to be retrieved first, as se->bufsize might change at anytime - the value used for allocation and must not differ from the value actually used. This also tries to set large sizes in passthrough_hp, to catch issues in xfstests - though requires to set /proc/sys/fs/fuse/max_pages_limit Signed-off-by: Bernd Schubert --- example/passthrough_hp.cc | 3 +++ lib/fuse_lowlevel.c | 16 ++++++++++------ 2 files changed, 13 insertions(+), 6 deletions(-) diff --git a/example/passthrough_hp.cc b/example/passthrough_hp.cc index 41904e5..d87ca5f 100644 --- a/example/passthrough_hp.cc +++ b/example/passthrough_hp.cc @@ -226,6 +226,9 @@ static void sfs_init(void *userdata, fuse_conn_info *conn) { /* Disable the receiving and processing of FUSE_INTERRUPT requests */ conn->no_interrupt = 1; + + /* Try a large IO by default */ + conn->max_write = 4 * 1024 * 1024; } diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c index 17bc816..9ebaaf0 100644 --- a/lib/fuse_lowlevel.c +++ b/lib/fuse_lowlevel.c @@ -3112,16 +3112,16 @@ pipe_retry: struct fuse_bufvec dst = { .count = 1 }; if (!buf->mem) { - buf->mem = buf_alloc(se->bufsize, internal); + buf->mem = buf_alloc(bufsize, internal); if (!buf->mem) { fuse_log( FUSE_LOG_ERR, "fuse: failed to allocate read buffer\n"); return -ENOMEM; } - buf->mem_size = se->bufsize; + buf->mem_size = bufsize; } - buf->size = se->bufsize; + buf->size = bufsize; buf->flags = 0; dst.buf[0] = *buf; @@ -3151,14 +3151,18 @@ pipe_retry: fallback: #endif + bufsize = internal ? buf->mem_size : se->bufsize; if (!buf->mem) { - buf->mem = buf_alloc(se->bufsize, internal); + bufsize = se->bufsize; /* might have changed */ + buf->mem = buf_alloc(bufsize, internal); if (!buf->mem) { fuse_log(FUSE_LOG_ERR, "fuse: failed to allocate read buffer\n"); return -ENOMEM; } - buf->mem_size = se->bufsize; + + if (internal) + buf->mem_size = bufsize; } restart: @@ -3175,7 +3179,7 @@ restart: if (fuse_session_exited(se)) return 0; if (res == -1) { - if (err == EINVAL && internal && se->bufsize > buf->mem_size) { + if (err == EINVAL && internal && se->bufsize > bufsize) { /* FUSE_INIT might have increased the required bufsize */ bufsize = se->bufsize; void *newbuf = buf_alloc(bufsize, internal); -- cgit v1.2.3