From 21f621741a770c119e7529a3f5c0e6b7c91383a3 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 6 Jan 2015 10:45:35 +0100 Subject: fuse: fix LOOKUP vs INIT compat handling Analysis from Marc: "Commit 7078187a795f ("fuse: introduce fuse_simple_request() helper") from the above pull request triggers some EIO errors for me in some tests that rely on fuse Looking at the code changes and a bit of debugging info I think there's a general problem here that fuse_get_req checks and possibly waits for fc->initialized, and this was always called first. But this commit changes the ordering and in many places fc->minor is now possibly used before fuse_get_req, and we can't be sure that fc has been initialized. In my case fuse_lookup_init sets req->out.args[0].size to the wrong size because fc->minor at that point is still 0, leading to the EIO error." Fix by moving the compat adjustments into fuse_simple_request() to after fuse_get_req(). This is also more readable than the original, since now compatibility is handled in a single function instead of cluttering each operation. Reported-by: Marc Dionne Tested-by: Marc Dionne Signed-off-by: Miklos Szeredi Fixes: 7078187a795f ("fuse: introduce fuse_simple_request() helper") --- fs/fuse/dev.c | 36 ++++++++++++++++++++++++++++++++++++ fs/fuse/dir.c | 31 +++++++------------------------ fs/fuse/inode.c | 3 +-- 3 files changed, 44 insertions(+), 26 deletions(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index ba1107977f2e..c847d6b225e2 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -511,6 +511,39 @@ void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req) } EXPORT_SYMBOL_GPL(fuse_request_send); +static void fuse_adjust_compat(struct fuse_conn *fc, struct fuse_args *args) +{ + if (fc->minor < 4 && args->in.h.opcode == FUSE_STATFS) + args->out.args[0].size = FUSE_COMPAT_STATFS_SIZE; + + if (fc->minor < 9) { + switch (args->in.h.opcode) { + case FUSE_LOOKUP: + case FUSE_CREATE: + case FUSE_MKNOD: + case FUSE_MKDIR: + case FUSE_SYMLINK: + case FUSE_LINK: + args->out.args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE; + break; + case FUSE_GETATTR: + case FUSE_SETATTR: + args->out.args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE; + break; + } + } + if (fc->minor < 12) { + switch (args->in.h.opcode) { + case FUSE_CREATE: + args->in.args[0].size = sizeof(struct fuse_open_in); + break; + case FUSE_MKNOD: + args->in.args[0].size = FUSE_COMPAT_MKNOD_IN_SIZE; + break; + } + } +} + ssize_t fuse_simple_request(struct fuse_conn *fc, struct fuse_args *args) { struct fuse_req *req; @@ -520,6 +553,9 @@ ssize_t fuse_simple_request(struct fuse_conn *fc, struct fuse_args *args) if (IS_ERR(req)) return PTR_ERR(req); + /* Needs to be done after fuse_get_req() so that fc->minor is valid */ + fuse_adjust_compat(fc, args); + req->in.h.opcode = args->in.h.opcode; req->in.h.nodeid = args->in.h.nodeid; req->in.numargs = args->in.numargs; diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 252b8a5de8b5..08e7b1a9d5d0 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -156,10 +156,7 @@ static void fuse_lookup_init(struct fuse_conn *fc, struct fuse_args *args, args->in.args[0].size = name->len + 1; args->in.args[0].value = name->name; args->out.numargs = 1; - if (fc->minor < 9) - args->out.args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE; - else - args->out.args[0].size = sizeof(struct fuse_entry_out); + args->out.args[0].size = sizeof(struct fuse_entry_out); args->out.args[0].value = outarg; } @@ -422,16 +419,12 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, args.in.h.opcode = FUSE_CREATE; args.in.h.nodeid = get_node_id(dir); args.in.numargs = 2; - args.in.args[0].size = fc->minor < 12 ? sizeof(struct fuse_open_in) : - sizeof(inarg); + args.in.args[0].size = sizeof(inarg); args.in.args[0].value = &inarg; args.in.args[1].size = entry->d_name.len + 1; args.in.args[1].value = entry->d_name.name; args.out.numargs = 2; - if (fc->minor < 9) - args.out.args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE; - else - args.out.args[0].size = sizeof(outentry); + args.out.args[0].size = sizeof(outentry); args.out.args[0].value = &outentry; args.out.args[1].size = sizeof(outopen); args.out.args[1].value = &outopen; @@ -539,10 +532,7 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_args *args, memset(&outarg, 0, sizeof(outarg)); args->in.h.nodeid = get_node_id(dir); args->out.numargs = 1; - if (fc->minor < 9) - args->out.args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE; - else - args->out.args[0].size = sizeof(outarg); + args->out.args[0].size = sizeof(outarg); args->out.args[0].value = &outarg; err = fuse_simple_request(fc, args); if (err) @@ -592,8 +582,7 @@ static int fuse_mknod(struct inode *dir, struct dentry *entry, umode_t mode, inarg.umask = current_umask(); args.in.h.opcode = FUSE_MKNOD; args.in.numargs = 2; - args.in.args[0].size = fc->minor < 12 ? FUSE_COMPAT_MKNOD_IN_SIZE : - sizeof(inarg); + args.in.args[0].size = sizeof(inarg); args.in.args[0].value = &inarg; args.in.args[1].size = entry->d_name.len + 1; args.in.args[1].value = entry->d_name.name; @@ -899,10 +888,7 @@ static int fuse_do_getattr(struct inode *inode, struct kstat *stat, args.in.args[0].size = sizeof(inarg); args.in.args[0].value = &inarg; args.out.numargs = 1; - if (fc->minor < 9) - args.out.args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE; - else - args.out.args[0].size = sizeof(outarg); + args.out.args[0].size = sizeof(outarg); args.out.args[0].value = &outarg; err = fuse_simple_request(fc, &args); if (!err) { @@ -1574,10 +1560,7 @@ static void fuse_setattr_fill(struct fuse_conn *fc, struct fuse_args *args, args->in.args[0].size = sizeof(*inarg_p); args->in.args[0].value = inarg_p; args->out.numargs = 1; - if (fc->minor < 9) - args->out.args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE; - else - args->out.args[0].size = sizeof(*outarg_p); + args->out.args[0].size = sizeof(*outarg_p); args->out.args[0].value = outarg_p; } diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 6749109f255d..6a20f2ff2c2e 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -424,8 +424,7 @@ static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf) args.in.h.opcode = FUSE_STATFS; args.in.h.nodeid = get_node_id(dentry->d_inode); args.out.numargs = 1; - args.out.args[0].size = - fc->minor < 4 ? FUSE_COMPAT_STATFS_SIZE : sizeof(outarg); + args.out.args[0].size = sizeof(outarg); args.out.args[0].value = &outarg; err = fuse_simple_request(fc, &args); if (!err) -- cgit v1.2.3 From 9759bd51899458af4f4bcc11046f01285642ca10 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 6 Jan 2015 10:45:35 +0100 Subject: fuse: add memory barrier to INIT Theoretically we need to order setting of various fields in fc with fc->initialized. No known bug reports related to this yet. Signed-off-by: Miklos Szeredi --- fs/fuse/dev.c | 15 +++++++++++++-- fs/fuse/fuse_i.h | 2 ++ fs/fuse/inode.c | 2 +- 3 files changed, 16 insertions(+), 3 deletions(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index c847d6b225e2..ed19a7d622fa 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -131,6 +131,13 @@ static void fuse_req_init_context(struct fuse_req *req) req->in.h.pid = current->pid; } +void fuse_set_initialized(struct fuse_conn *fc) +{ + /* Make sure stores before this are seen on another CPU */ + smp_wmb(); + fc->initialized = 1; +} + static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background) { return !fc->initialized || (for_background && fc->blocked); @@ -155,6 +162,8 @@ static struct fuse_req *__fuse_get_req(struct fuse_conn *fc, unsigned npages, if (intr) goto out; } + /* Matches smp_wmb() in fuse_set_initialized() */ + smp_rmb(); err = -ENOTCONN; if (!fc->connected) @@ -253,6 +262,8 @@ struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc, atomic_inc(&fc->num_waiting); wait_event(fc->blocked_waitq, fc->initialized); + /* Matches smp_wmb() in fuse_set_initialized() */ + smp_rmb(); req = fuse_request_alloc(0); if (!req) req = get_reserved_req(fc, file); @@ -2163,7 +2174,7 @@ void fuse_abort_conn(struct fuse_conn *fc) if (fc->connected) { fc->connected = 0; fc->blocked = 0; - fc->initialized = 1; + fuse_set_initialized(fc); end_io_requests(fc); end_queued_requests(fc); end_polls(fc); @@ -2182,7 +2193,7 @@ int fuse_dev_release(struct inode *inode, struct file *file) spin_lock(&fc->lock); fc->connected = 0; fc->blocked = 0; - fc->initialized = 1; + fuse_set_initialized(fc); end_queued_requests(fc); end_polls(fc); wake_up_all(&fc->blocked_waitq); diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index e0fc6725d1d0..1cdfb07c1376 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -906,4 +906,6 @@ int fuse_write_inode(struct inode *inode, struct writeback_control *wbc); int fuse_do_setattr(struct inode *inode, struct iattr *attr, struct file *file); +void fuse_set_initialized(struct fuse_conn *fc); + #endif /* _FS_FUSE_I_H */ diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 6a20f2ff2c2e..f38256e4476e 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -897,7 +897,7 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req) fc->max_write = max_t(unsigned, 4096, fc->max_write); fc->conn_init = 1; } - fc->initialized = 1; + fuse_set_initialized(fc); wake_up_all(&fc->blocked_waitq); } -- cgit v1.2.3