From 8373200b124d03de7fa2e99be56de8642e604e9e Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Thu, 10 Oct 2013 17:10:46 +0400 Subject: [PATCH] fuse: Trust kernel i_size only Make fuse think that when writeback is on the inode's i_size is always up-to-date and not update it with the value received from the userspace. This is done because the page cache code may update i_size without letting the FS know. This assumption implies fixing the previously introduced short-read helper -- when a short read occurs the 'hole' is filled with zeroes. fuse_file_fallocate() is also fixed because now we should keep i_size up to date, so it must be updated if FUSE_FALLOCATE request succeeded. Signed-off-by: Maxim V. Patlasov Signed-off-by: Miklos Szeredi --- fs/fuse/dir.c | 13 +++++++++++-- fs/fuse/file.c | 21 +++++++++++++++++++-- fs/fuse/inode.c | 11 +++++++++-- 3 files changed, 39 insertions(+), 6 deletions(-) diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 1d1292c581c3..c52f143da9ad 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -839,6 +839,11 @@ static void fuse_fillattr(struct inode *inode, struct fuse_attr *attr, struct kstat *stat) { unsigned int blkbits; + struct fuse_conn *fc = get_fuse_conn(inode); + + /* see the comment in fuse_change_attributes() */ + if (fc->writeback_cache && S_ISREG(inode->i_mode)) + attr->size = i_size_read(inode); stat->dev = inode->i_sb->s_dev; stat->ino = attr->ino; @@ -1580,6 +1585,7 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr, struct fuse_setattr_in inarg; struct fuse_attr_out outarg; bool is_truncate = false; + bool is_wb = fc->writeback_cache; loff_t oldsize; int err; @@ -1651,7 +1657,9 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr, fuse_change_attributes_common(inode, &outarg.attr, attr_timeout(&outarg)); oldsize = inode->i_size; - i_size_write(inode, outarg.attr.size); + /* see the comment in fuse_change_attributes() */ + if (!is_wb || is_truncate || !S_ISREG(inode->i_mode)) + i_size_write(inode, outarg.attr.size); if (is_truncate) { /* NOTE: this may release/reacquire fc->lock */ @@ -1663,7 +1671,8 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr, * Only call invalidate_inode_pages2() after removing * FUSE_NOWRITE, otherwise fuse_launder_page() would deadlock. */ - if (S_ISREG(inode->i_mode) && oldsize != outarg.attr.size) { + if ((is_truncate || !is_wb) && + S_ISREG(inode->i_mode) && oldsize != outarg.attr.size) { truncate_pagecache(inode, outarg.attr.size); invalidate_inode_pages2(inode->i_mapping); } diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 592d7b48e421..c091a17d3ffc 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -675,9 +675,26 @@ static void fuse_short_read(struct fuse_req *req, struct inode *inode, u64 attr_ver) { size_t num_read = req->out.args[0].size; + struct fuse_conn *fc = get_fuse_conn(inode); + + if (fc->writeback_cache) { + /* + * A hole in a file. Some data after the hole are in page cache, + * but have not reached the client fs yet. So, the hole is not + * present there. + */ + int i; + int start_idx = num_read >> PAGE_CACHE_SHIFT; + size_t off = num_read & (PAGE_CACHE_SIZE - 1); - loff_t pos = page_offset(req->pages[0]) + num_read; - fuse_read_update_size(inode, pos, attr_ver); + for (i = start_idx; i < req->num_pages; i++) { + zero_user_segment(req->pages[i], off, PAGE_CACHE_SIZE); + off = 0; + } + } else { + loff_t pos = page_offset(req->pages[0]) + num_read; + fuse_read_update_size(inode, pos, attr_ver); + } } static int fuse_readpage(struct file *file, struct page *page) diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index d468643a68b2..c668c8436894 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -197,6 +197,7 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr, { struct fuse_conn *fc = get_fuse_conn(inode); struct fuse_inode *fi = get_fuse_inode(inode); + bool is_wb = fc->writeback_cache; loff_t oldsize; struct timespec old_mtime; @@ -211,10 +212,16 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr, fuse_change_attributes_common(inode, attr, attr_valid); oldsize = inode->i_size; - i_size_write(inode, attr->size); + /* + * In case of writeback_cache enabled, the cached writes beyond EOF + * extend local i_size without keeping userspace server in sync. So, + * attr->size coming from server can be stale. We cannot trust it. + */ + if (!is_wb || !S_ISREG(inode->i_mode)) + i_size_write(inode, attr->size); spin_unlock(&fc->lock); - if (S_ISREG(inode->i_mode)) { + if (!is_wb && S_ISREG(inode->i_mode)) { bool inval = false; if (oldsize != attr->size) { -- 2.30.2