From 495e86779f4f319828bc10dfc0c9ac2161868077 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 19 Nov 2010 20:36:10 +0000 Subject: Btrfs: hold i_mutex when calling btrfs_log_dentry_safe Since we walk up the path logging all of the parts of the inode's path, we need to hold i_mutex to make sure that the inode is not renamed while we're logging everything. btrfs_log_dentry_safe does dget_parent and all of that jazz, but we may get unexpected results if the rename changes the inode's location while we're higher up the path logging those dentries, so do this for safety reasons. Thanks, Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/file.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'fs/btrfs/file.c') diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index e354c33df082..c1faded5fca0 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1047,8 +1047,14 @@ out: if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) { trans = btrfs_start_transaction(root, 0); + if (IS_ERR(trans)) { + num_written = PTR_ERR(trans); + goto done; + } + mutex_lock(&inode->i_mutex); ret = btrfs_log_dentry_safe(trans, root, file->f_dentry); + mutex_unlock(&inode->i_mutex); if (ret == 0) { ret = btrfs_sync_log(trans, root); if (ret == 0) @@ -1067,6 +1073,7 @@ out: (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT); } } +done: current->backing_dev_info = NULL; return num_written ? num_written : err; } -- cgit v1.2.3 From 914ee295af418e936ec20a08c1663eaabe4cd07a Mon Sep 17 00:00:00 2001 From: Xin Zhong Date: Thu, 9 Dec 2010 09:30:14 +0000 Subject: Btrfs: pwrite blocked when writing from the mmaped buffer of the same page This problem is found in meego testing: http://bugs.meego.com/show_bug.cgi?id=6672 A file in btrfs is mmaped and the mmaped buffer is passed to pwrite to write to the same page of the same file. In btrfs_file_aio_write(), the pages is locked by prepare_pages(). So when btrfs_copy_from_user() is called, page fault happens and the same page needs to be locked again in filemap_fault(). The fix is to move iov_iter_fault_in_readable() before prepage_pages() to make page fault happen before pages are locked. And also disable page fault in critical region in btrfs_copy_from_user(). Reviewed-by: Yan, Zheng Signed-off-by: Zhong, Xin Signed-off-by: Chris Mason --- fs/btrfs/file.c | 92 +++++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 60 insertions(+), 32 deletions(-) (limited to 'fs/btrfs/file.c') diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index c1faded5fca0..66836d85763b 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -48,30 +48,34 @@ static noinline int btrfs_copy_from_user(loff_t pos, int num_pages, struct page **prepared_pages, struct iov_iter *i) { - size_t copied; + size_t copied = 0; int pg = 0; int offset = pos & (PAGE_CACHE_SIZE - 1); + int total_copied = 0; while (write_bytes > 0) { size_t count = min_t(size_t, PAGE_CACHE_SIZE - offset, write_bytes); struct page *page = prepared_pages[pg]; -again: - if (unlikely(iov_iter_fault_in_readable(i, count))) - return -EFAULT; - - /* Copy data from userspace to the current page */ - copied = iov_iter_copy_from_user(page, i, offset, count); + /* + * Copy data from userspace to the current page + * + * Disable pagefault to avoid recursive lock since + * the pages are already locked + */ + pagefault_disable(); + copied = iov_iter_copy_from_user_atomic(page, i, offset, count); + pagefault_enable(); /* Flush processor's dcache for this page */ flush_dcache_page(page); iov_iter_advance(i, copied); write_bytes -= copied; + total_copied += copied; + /* Return to btrfs_file_aio_write to fault page */ if (unlikely(copied == 0)) { - count = min_t(size_t, PAGE_CACHE_SIZE - offset, - iov_iter_single_seg_count(i)); - goto again; + break; } if (unlikely(copied < PAGE_CACHE_SIZE - offset)) { @@ -81,7 +85,7 @@ again: offset = 0; } } - return 0; + return total_copied; } /* @@ -854,6 +858,8 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb, unsigned long last_index; int will_write; int buffered = 0; + int copied = 0; + int dirty_pages = 0; will_write = ((file->f_flags & O_DSYNC) || IS_SYNC(inode) || (file->f_flags & O_DIRECT)); @@ -970,7 +976,17 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb, WARN_ON(num_pages > nrptrs); memset(pages, 0, sizeof(struct page *) * nrptrs); - ret = btrfs_delalloc_reserve_space(inode, write_bytes); + /* + * Fault pages before locking them in prepare_pages + * to avoid recursive lock + */ + if (unlikely(iov_iter_fault_in_readable(&i, write_bytes))) { + ret = -EFAULT; + goto out; + } + + ret = btrfs_delalloc_reserve_space(inode, + num_pages << PAGE_CACHE_SHIFT); if (ret) goto out; @@ -978,37 +994,49 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb, pos, first_index, last_index, write_bytes); if (ret) { - btrfs_delalloc_release_space(inode, write_bytes); + btrfs_delalloc_release_space(inode, + num_pages << PAGE_CACHE_SHIFT); goto out; } - ret = btrfs_copy_from_user(pos, num_pages, + copied = btrfs_copy_from_user(pos, num_pages, write_bytes, pages, &i); - if (ret == 0) { + dirty_pages = (copied + PAGE_CACHE_SIZE - 1) >> + PAGE_CACHE_SHIFT; + + if (num_pages > dirty_pages) { + if (copied > 0) + atomic_inc( + &BTRFS_I(inode)->outstanding_extents); + btrfs_delalloc_release_space(inode, + (num_pages - dirty_pages) << + PAGE_CACHE_SHIFT); + } + + if (copied > 0) { dirty_and_release_pages(NULL, root, file, pages, - num_pages, pos, write_bytes); + dirty_pages, pos, copied); } btrfs_drop_pages(pages, num_pages); - if (ret) { - btrfs_delalloc_release_space(inode, write_bytes); - goto out; - } - if (will_write) { - filemap_fdatawrite_range(inode->i_mapping, pos, - pos + write_bytes - 1); - } else { - balance_dirty_pages_ratelimited_nr(inode->i_mapping, - num_pages); - if (num_pages < - (root->leafsize >> PAGE_CACHE_SHIFT) + 1) - btrfs_btree_balance_dirty(root, 1); - btrfs_throttle(root); + if (copied > 0) { + if (will_write) { + filemap_fdatawrite_range(inode->i_mapping, pos, + pos + copied - 1); + } else { + balance_dirty_pages_ratelimited_nr( + inode->i_mapping, + dirty_pages); + if (dirty_pages < + (root->leafsize >> PAGE_CACHE_SHIFT) + 1) + btrfs_btree_balance_dirty(root, 1); + btrfs_throttle(root); + } } - pos += write_bytes; - num_written += write_bytes; + pos += copied; + num_written += copied; cond_resched(); } -- cgit v1.2.3