@@ -1583,7 +1583,7 @@ xfs_inode_free_cowblocks(
ASSERT(!eofb || (eofb && eofb->eof_scan_owner != 0));
- if (!xfs_reflink_has_real_cow_blocks(ip)) {
+ if (!xfs_reflink_has_cow_blocks(ip)) {
trace_xfs_inode_free_cowblocks_invalid(ip);
xfs_inode_clear_cowblocks_tag(ip);
return 0;
@@ -1699,35 +1699,20 @@ xfs_reflink_unshare(
}
/*
- * Does this inode have any real CoW reservations?
+ * Does this inode have any CoW reservations?
*/
bool
-xfs_reflink_has_real_cow_blocks(
+xfs_reflink_has_cow_blocks(
struct xfs_inode *ip)
{
- struct xfs_bmbt_irec irec;
struct xfs_ifork *ifp;
- struct xfs_bmbt_rec_host *gotp;
- xfs_extnum_t idx;
if (!xfs_is_reflink_inode(ip))
return false;
- /* Go find the old extent in the CoW fork. */
ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
- gotp = xfs_iext_bno_to_ext(ifp, 0, &idx);
- while (gotp) {
- xfs_bmbt_get_all(gotp, &irec);
-
- if (!isnullstartblock(irec.br_startblock))
- return true;
-
- /* Roll on... */
- idx++;
- if (idx >= ifp->if_bytes / sizeof(xfs_bmbt_rec_t))
- break;
- gotp = xfs_iext_get_ext(ifp, idx);
- }
+ if (ifp->if_bytes)
+ return true;
return false;
}
@@ -50,6 +50,6 @@ extern int xfs_reflink_clear_inode_flag(struct xfs_inode *ip,
extern int xfs_reflink_unshare(struct xfs_inode *ip, xfs_off_t offset,
xfs_off_t len);
-extern bool xfs_reflink_has_real_cow_blocks(struct xfs_inode *ip);
+extern bool xfs_reflink_has_cow_blocks(struct xfs_inode *ip);
#endif /* __XFS_REFLINK_H */
The cowblocks background scanner currently clears the cowblocks tag for inodes without any real allocations in the cow fork. This excludes inodes with only delalloc blocks in the cow fork. While we might never expect to clear delalloc blocks from the cow fork in the background scanner, it is not necessarily correct to clear the cowblocks tag from such inodes. For example, if the background scanner happens to process an inode between a buffered write and writeback, the scanner catches the inode in a state after delalloc blocks have been allocated to the cow fork but before the delalloc blocks have been converted to real blocks by writeback. The background scanner then incorrectly clears the cowblocks tag, even if part of the aforementioned delalloc reservation will not be remapped to the data fork (i.e., extra blocks due to the cowextsize hint). This means that any such additional blocks in the cow fork might never be reclaimed by the background scanner and could persist until the inode itself is reclaimed. To address this problem, only skip and clear inodes without any cow fork allocations whatsoever from the background scanner. While we generally do not want to cancel delalloc reservations from the background scanner, the pagecache dirty check following the cowblocks check should prevent that situation. If we do end up with delalloc cow fork blocks without a dirty address space mapping, this is probably an indication that something has gone wrong and the blocks should be reclaimed, as they may never be converted to a real allocation. XXX: There are probably multiple ways to deal with this. Another option could be to tweak the has_cow_blocks() helper to separately return whether a cow fork has delalloc blocks and skip over the inode without actually clearing the tag. Thoughts? Signed-off-by: Brian Foster <bfoster@redhat.com> --- fs/xfs/xfs_icache.c | 2 +- fs/xfs/xfs_reflink.c | 23 ++++------------------- fs/xfs/xfs_reflink.h | 2 +- 3 files changed, 6 insertions(+), 21 deletions(-)