On Tue, Feb 11, 2020 at 11:32 AM Luis Henriques lhenriques@suse.com wrote:
On Mon, Feb 10, 2020 at 07:38:10PM +0100, Ilya Dryomov wrote:
On Thu, Feb 6, 2020 at 11:38 AM Luis Henriques lhenriques@suse.com wrote:
When there's an error in the copying loop but some bytes have already been copied into the destination file, it is necessary to dirty the caps and eventually update the MDS with the file metadata (timestamps, size). This patch fixes this error path.
Another issue this patch fixes is the destination file size being reported to the MDS. If we're on the error path but the amount of bytes written has already changed the destination file size, the offset to use is dst_off and not endoff.
Cc: stable@vger.kernel.org Signed-off-by: Luis Henriques lhenriques@suse.com
fs/ceph/file.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/fs/ceph/file.c b/fs/ceph/file.c index 11929d2bb594..f7f8cb6c243f 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -2104,9 +2104,16 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off, CEPH_OSD_OP_FLAG_FADVISE_DONTNEED, 0); if (err) { dout("ceph_osdc_copy_from returned %d\n", err);
if (!ret)
/** If we haven't done any copy yet, just exit with the* error code; otherwise, return the number of bytes* already copied, update metadata and dirty caps.*/if (!ret) { ret = err;
goto out_caps;
goto out_caps;}goto update_dst_inode; } len -= object_size; src_off += object_size;@@ -2118,16 +2125,17 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off, /* We still need one final local copy */ do_final_copy = true;
+update_dst_inode: file_update_time(dst_file); inode_inc_iversion_raw(dst_inode);
if (endoff > size) {
if (dst_off > size) { int caps_flags = 0; /* Let the MDS know about dst file size change */
if (ceph_quota_is_max_bytes_approaching(dst_inode, endoff))
if (ceph_quota_is_max_bytes_approaching(dst_inode, dst_off)) caps_flags |= CHECK_CAPS_NODELAY;
if (ceph_inode_set_size(dst_inode, endoff))
if (ceph_inode_set_size(dst_inode, dst_off)) caps_flags |= CHECK_CAPS_AUTHONLY; if (caps_flags) ceph_check_caps(dst_ci, caps_flags, NULL);Hi Luis,
I think this function still has short copy and file size issues:
do_splice_direct() may write fewer bytes than requested, including nothing at all (i.e. return 0). While we don't care about the second call much, handling the first call is crucial because proceeding to the copy-from loop with src/dst_off not at the object boundary will corrupt the destination file.
size is set after caps are acquired for the first time and never updated. But caps are dropped before do_splice_direct(), so by the time we get to dst_off > size check, it may be stale. Again, data loss if e.g. old-size < dst_off < new-size because the destination file will get truncated...
Also, src/dst_oloc need to be freed with ceph_oloc_destroy() to avoid leaking memory on namespace layouts.
It seems clear that this function needs to be split, with the new loop around do_splice_direct() and the copy-from loop each going into a separate functions with clear pre- and post-conditions.
Right, it makes sense to refactor this function and fix all these issues you're pointing. It'll be a pain because a lot of parameters will need to be handed over into these new functions (maybe a new 'struct copy_desc' can help making it a bit less messy). Anyway, I'll try to spend some time working on that and see what I can come up with.
Yeah, this code really needs more work and extensive verification.
I'm dropping this patch because it's only a partial fix. Backporting it alone, with known data corruption issues remaining (and without the copy-from2 patch that fixes another data corruption issue that is much easier to hit), doesn't make sense.
Thanks,
Ilya