From: Miklos Szeredi Date: Tue, 17 Oct 2006 07:10:06 +0000 (-0700) Subject: [PATCH] fuse: fix hang on SMP X-Git-Tag: v2.6.19-rc3~180 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9ffbb9162312fd8113037cb3d94f787f06bbfa9a;p=linux-2.6 [PATCH] fuse: fix hang on SMP Fuse didn't always call i_size_write() with i_mutex held which caused rare hangs on SMP/32bit. This bug has been present since fuse-2.2, well before being merged into mainline. The simplest solution is to protect i_size_write() with the per-connection spinlock. Using i_mutex for this purpose would require some restructuring of the code and I'm not even sure it's always safe to acquire i_mutex in all places i_size needs to be set. Since most of vmtruncate is already duplicated for other reasons, duplicate the remaining part as well, making all i_size_write() calls internal to fuse. Using i_size_write() was unnecessary in fuse_init_inode(), since this function is only called on a newly created locked inode. Reported by a few people over the years, but special thanks to Dana Henriksen who was persistent enough in helping me debug it. Signed-off-by: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 8605155db1..a8f65c11aa 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -935,14 +935,30 @@ static void iattr_to_fattr(struct iattr *iattr, struct fuse_setattr_in *arg) } } +static void fuse_vmtruncate(struct inode *inode, loff_t offset) +{ + struct fuse_conn *fc = get_fuse_conn(inode); + int need_trunc; + + spin_lock(&fc->lock); + need_trunc = inode->i_size > offset; + i_size_write(inode, offset); + spin_unlock(&fc->lock); + + if (need_trunc) { + struct address_space *mapping = inode->i_mapping; + unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); + truncate_inode_pages(mapping, offset); + } +} + /* * Set attributes, and at the same time refresh them. * * Truncation is slightly complicated, because the 'truncate' request * may fail, in which case we don't want to touch the mapping. - * vmtruncate() doesn't allow for this case. So do the rlimit - * checking by hand and call vmtruncate() only after the file has - * actually been truncated. + * vmtruncate() doesn't allow for this case, so do the rlimit checking + * and the actual truncation by hand. */ static int fuse_setattr(struct dentry *entry, struct iattr *attr) { @@ -993,12 +1009,8 @@ static int fuse_setattr(struct dentry *entry, struct iattr *attr) make_bad_inode(inode); err = -EIO; } else { - if (is_truncate) { - loff_t origsize = i_size_read(inode); - i_size_write(inode, outarg.attr.size); - if (origsize > outarg.attr.size) - vmtruncate(inode, outarg.attr.size); - } + if (is_truncate) + fuse_vmtruncate(inode, outarg.attr.size); fuse_change_attributes(inode, &outarg.attr); fi->i_time = time_to_jiffies(outarg.attr_valid, outarg.attr_valid_nsec); diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 183626868e..2bb5ace388 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -481,8 +481,10 @@ static int fuse_commit_write(struct file *file, struct page *page, err = -EIO; if (!err) { pos += count; - if (pos > i_size_read(inode)) + spin_lock(&fc->lock); + if (pos > inode->i_size) i_size_write(inode, pos); + spin_unlock(&fc->lock); if (offset == 0 && to == PAGE_CACHE_SIZE) { clear_page_dirty(page); @@ -586,8 +588,12 @@ static ssize_t fuse_direct_io(struct file *file, const char __user *buf, } fuse_put_request(fc, req); if (res > 0) { - if (write && pos > i_size_read(inode)) - i_size_write(inode, pos); + if (write) { + spin_lock(&fc->lock); + if (pos > inode->i_size) + i_size_write(inode, pos); + spin_unlock(&fc->lock); + } *ppos = pos; } fuse_invalidate_attr(inode); diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 7d0a9aee01..8e106163aa 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -109,6 +109,7 @@ static int fuse_remount_fs(struct super_block *sb, int *flags, char *data) void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr) { + struct fuse_conn *fc = get_fuse_conn(inode); if (S_ISREG(inode->i_mode) && i_size_read(inode) != attr->size) invalidate_inode_pages(inode->i_mapping); @@ -117,7 +118,9 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr) inode->i_nlink = attr->nlink; inode->i_uid = attr->uid; inode->i_gid = attr->gid; + spin_lock(&fc->lock); i_size_write(inode, attr->size); + spin_unlock(&fc->lock); inode->i_blocks = attr->blocks; inode->i_atime.tv_sec = attr->atime; inode->i_atime.tv_nsec = attr->atimensec; @@ -130,7 +133,7 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr) static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr) { inode->i_mode = attr->mode & S_IFMT; - i_size_write(inode, attr->size); + inode->i_size = attr->size; if (S_ISREG(inode->i_mode)) { fuse_init_common(inode); fuse_init_file_inode(inode);