diff options
| -rw-r--r-- | Documentation/filesystems/vfs.txt | 5 | ||||
| -rw-r--r-- | fs/libfs.c | 5 |
2 files changed, 8 insertions, 2 deletions
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index 7737bfd03cf8..ea271f2d3954 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -617,6 +617,11 @@ struct address_space_operations { In this case the prepare_write will be retried one the lock is regained. + Note: the page _must not_ be marked uptodate in this function + (or anywhere else) unless it actually is uptodate right now. As + soon as a page is marked uptodate, it is possible for a concurrent + read(2) to copy it to userspace. + commit_write: If prepare_write succeeds, new data will be copied into the page and then commit_write will be called. It will typically update the size of the file (if appropriate) and diff --git a/fs/libfs.c b/fs/libfs.c index 7d487047dbb8..cf79196535ec 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -335,17 +335,18 @@ int simple_prepare_write(struct file *file, struct page *page, flush_dcache_page(page); kunmap_atomic(kaddr, KM_USER0); } - SetPageUptodate(page); } return 0; } int simple_commit_write(struct file *file, struct page *page, - unsigned offset, unsigned to) + unsigned from, unsigned to) { struct inode *inode = page->mapping->host; loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; + if (!PageUptodate(page)) + SetPageUptodate(page); /* * No need to use i_size_read() here, the i_size * cannot change under us because we hold the i_mutex. |