| Message ID | 1443608912-31667-13-git-send-email-chandan@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 09/30/2015 06:28 AM, Chandan Rajendra wrote: > When reading the page from the disk, we can race with Direct I/O which can get > the page lock (before prepare_uptodate_page() gets it) and can go ahead and > invalidate the page. Hence if the page is not found in the inode's address > space, retry the operation of getting a page. > > Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> > --- Huh, how in the world did you make that happen? Reviewed-by: Josef Bacik <jbacik@fb.com> Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thursday 01 Oct 2015 10:50:30 Josef Bacik wrote: > On 09/30/2015 06:28 AM, Chandan Rajendra wrote: > > When reading the page from the disk, we can race with Direct I/O which can > > get the page lock (before prepare_uptodate_page() gets it) and can go > > ahead and invalidate the page. Hence if the page is not found in the > > inode's address space, retry the operation of getting a page. > > > > Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> > > --- > > Huh, how in the world did you make that happen? > The issue is seen when generic/095 test is run in a loop. I would like to add, Reported-by: Jakub Palider <jpa@semihalf.com> > Reviewed-by: Josef Bacik <jbacik@fb.com> > > Thanks, > > Josef
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 5715e29..76db77c 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1316,6 +1316,7 @@ static noinline int prepare_pages(struct inode *inode, struct page **pages, int faili; for (i = 0; i < num_pages; i++) { +again: pages[i] = find_or_create_page(inode->i_mapping, index + i, mask | __GFP_WRITE); if (!pages[i]) { @@ -1330,6 +1331,21 @@ static noinline int prepare_pages(struct inode *inode, struct page **pages, if (i == num_pages - 1) err = prepare_uptodate_page(pages[i], pos + write_bytes, false); + + /* + * When reading the page from the disk, we can race + * with direct i/o which can get the page lock (before + * prepare_uptodate_page() gets it) and can go ahead + * and invalidate the page. Hence if the page is found + * to be not belonging to the inode's address space, + * retry the operation of getting a page. + */ + if (unlikely(pages[i]->mapping != inode->i_mapping)) { + unlock_page(pages[i]); + page_cache_release(pages[i]); + goto again; + } + if (err) { page_cache_release(pages[i]); faili = i - 1;
When reading the page from the disk, we can race with Direct I/O which can get the page lock (before prepare_uptodate_page() gets it) and can go ahead and invalidate the page. Hence if the page is not found in the inode's address space, retry the operation of getting a page. Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> --- fs/btrfs/file.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)