From f7e9e8fc792fe2f823ff7d64d23f4363b3f2203a Mon Sep 17 00:00:00 2001 From: Omar Sandoval Date: Fri, 11 May 2018 13:13:32 -0700 Subject: [PATCH] Btrfs: stop creating orphan items for truncate Currently, we insert an orphan item during a truncate so that if there's a crash, we don't leak extents past the on-disk i_size. However, since commit 7f4f6e0a3f6d ("Btrfs: only update disk_i_size as we remove extents"), we keep disk_i_size in sync with the extent items as we truncate, so orphan cleanup will never have any extents to remove. Don't bother with the superfluous orphan item. Reviewed-by: Josef Bacik Signed-off-by: Omar Sandoval Signed-off-by: David Sterba --- fs/btrfs/free-space-cache.c | 6 +- fs/btrfs/inode.c | 159 +++++++++++------------------------- 2 files changed, 51 insertions(+), 114 deletions(-) diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index e5b569bebc73..d5f80cb300be 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -253,10 +253,8 @@ int btrfs_truncate_free_space_cache(struct btrfs_trans_handle *trans, truncate_pagecache(inode, 0); /* - * We don't need an orphan item because truncating the free space cache - * will never be split across transactions. - * We don't need to check for -EAGAIN because we're a free space - * cache inode + * We skip the throttling logic for free space cache inodes, so we don't + * need to check for -EAGAIN. */ ret = btrfs_truncate_inode_items(trans, root, inode, 0, BTRFS_EXTENT_DATA_KEY); diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index c966fd6e2cef..74caec73b7c2 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -3346,8 +3346,8 @@ void btrfs_orphan_commit_root(struct btrfs_trans_handle *trans, } /* - * This creates an orphan entry for the given inode in case something goes - * wrong in the middle of an unlink/truncate. + * This creates an orphan entry for the given inode in case something goes wrong + * in the middle of an unlink. * * NOTE: caller of this function should reserve 5 units of metadata for * this function. @@ -3410,7 +3410,7 @@ int btrfs_orphan_add(struct btrfs_trans_handle *trans, } } - /* insert an orphan item to track this unlinked/truncated file */ + /* insert an orphan item to track this unlinked file */ if (insert) { ret = btrfs_insert_orphan_item(trans, root, btrfs_ino(inode)); if (ret) { @@ -3439,8 +3439,8 @@ int btrfs_orphan_add(struct btrfs_trans_handle *trans, } /* - * We have done the truncate/delete so we can go ahead and remove the orphan - * item for this particular inode. + * We have done the delete so we can go ahead and remove the orphan item for + * this particular inode. */ static int btrfs_orphan_del(struct btrfs_trans_handle *trans, struct btrfs_inode *inode) @@ -3484,7 +3484,7 @@ int btrfs_orphan_cleanup(struct btrfs_root *root) struct btrfs_trans_handle *trans; struct inode *inode; u64 last_objectid = 0; - int ret = 0, nr_unlink = 0, nr_truncate = 0; + int ret = 0, nr_unlink = 0; if (cmpxchg(&root->orphan_cleanup_state, 0, ORPHAN_CLEANUP_STARTED)) return 0; @@ -3584,12 +3584,31 @@ int btrfs_orphan_cleanup(struct btrfs_root *root) key.offset = found_key.objectid - 1; continue; } + } + /* - * Inode is already gone but the orphan item is still there, - * kill the orphan item. + * If we have an inode with links, there are a couple of + * possibilities. Old kernels (before v3.12) used to create an + * orphan item for truncate indicating that there were possibly + * extent items past i_size that needed to be deleted. In v3.12, + * truncate was changed to update i_size in sync with the extent + * items, but the (useless) orphan item was still created. Since + * v4.18, we don't create the orphan item for truncate at all. + * + * So, this item could mean that we need to do a truncate, but + * only if this filesystem was last used on a pre-v3.12 kernel + * and was not cleanly unmounted. The odds of that are quite + * slim, and it's a pain to do the truncate now, so just delete + * the orphan item. + * + * It's also possible that this orphan item was supposed to be + * deleted but wasn't. The inode number may have been reused, + * but either way, we can delete the orphan item. */ - if (ret == -ENOENT) { + if (ret == -ENOENT || inode->i_nlink) { + if (!ret) + iput(inode); trans = btrfs_start_transaction(root, 1); if (IS_ERR(trans)) { ret = PTR_ERR(trans); @@ -3613,34 +3632,7 @@ int btrfs_orphan_cleanup(struct btrfs_root *root) &BTRFS_I(inode)->runtime_flags); atomic_inc(&root->orphan_inodes); - /* if we have links, this was a truncate, lets do that */ - if (inode->i_nlink) { - if (WARN_ON(!S_ISREG(inode->i_mode))) { - iput(inode); - continue; - } - nr_truncate++; - - /* 1 for the orphan item deletion. */ - trans = btrfs_start_transaction(root, 1); - if (IS_ERR(trans)) { - iput(inode); - ret = PTR_ERR(trans); - goto out; - } - ret = btrfs_orphan_add(trans, BTRFS_I(inode)); - btrfs_end_transaction(trans); - if (ret) { - iput(inode); - goto out; - } - - ret = btrfs_truncate(inode, false); - if (ret) - btrfs_orphan_del(NULL, BTRFS_I(inode)); - } else { - nr_unlink++; - } + nr_unlink++; /* this will do delete_inode and everything for us */ iput(inode); @@ -3665,8 +3657,6 @@ int btrfs_orphan_cleanup(struct btrfs_root *root) if (nr_unlink) btrfs_debug(fs_info, "unlinked %d orphans", nr_unlink); - if (nr_truncate) - btrfs_debug(fs_info, "truncated %d orphans", nr_truncate); out: if (ret) @@ -5350,29 +5340,6 @@ static int btrfs_setsize(struct inode *inode, struct iattr *attr) set_bit(BTRFS_INODE_ORDERED_DATA_CLOSE, &BTRFS_I(inode)->runtime_flags); - /* - * 1 for the orphan item we're going to add - * 1 for the orphan item deletion. - */ - trans = btrfs_start_transaction(root, 2); - if (IS_ERR(trans)) - return PTR_ERR(trans); - - /* - * We need to do this in case we fail at _any_ point during the - * actual truncate. Once we do the truncate_setsize we could - * invalidate pages which forces any outstanding ordered io to - * be instantly completed which will give us extents that need - * to be truncated. If we fail to get an orphan inode down we - * could have left over extents that were never meant to live, - * so we need to guarantee from this point on that everything - * will be consistent. - */ - ret = btrfs_orphan_add(trans, BTRFS_I(inode)); - btrfs_end_transaction(trans); - if (ret) - return ret; - truncate_setsize(inode, newsize); /* Disable nonlocked read DIO to avoid the end less truncate */ @@ -5384,29 +5351,16 @@ static int btrfs_setsize(struct inode *inode, struct iattr *attr) if (ret && inode->i_nlink) { int err; - /* To get a stable disk_i_size */ - err = btrfs_wait_ordered_range(inode, 0, (u64)-1); - if (err) { - btrfs_orphan_del(NULL, BTRFS_I(inode)); - return err; - } - /* - * failed to truncate, disk_i_size is only adjusted down - * as we remove extents, so it should represent the true - * size of the inode, so reset the in memory size and - * delete our orphan entry. + * Truncate failed, so fix up the in-memory size. We + * adjusted disk_i_size down as we removed extents, so + * wait for disk_i_size to be stable and then update the + * in-memory size to match. */ - trans = btrfs_join_transaction(root); - if (IS_ERR(trans)) { - btrfs_orphan_del(NULL, BTRFS_I(inode)); - return ret; - } - i_size_write(inode, BTRFS_I(inode)->disk_i_size); - err = btrfs_orphan_del(trans, BTRFS_I(inode)); + err = btrfs_wait_ordered_range(inode, 0, (u64)-1); if (err) - btrfs_abort_transaction(trans, err); - btrfs_end_transaction(trans); + return err; + i_size_write(inode, BTRFS_I(inode)->disk_i_size); } } @@ -9224,39 +9178,31 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback) } /* - * Yes ladies and gentlemen, this is indeed ugly. The fact is we have - * 3 things going on here - * - * 1) We need to reserve space for our orphan item and the space to - * delete our orphan item. Lord knows we don't want to have a dangling - * orphan item because we didn't reserve space to remove it. + * Yes ladies and gentlemen, this is indeed ugly. We have a couple of + * things going on here: * - * 2) We need to reserve space to update our inode. + * 1) We need to reserve space to update our inode. * - * 3) We need to have something to cache all the space that is going to + * 2) We need to have something to cache all the space that is going to * be free'd up by the truncate operation, but also have some slack * space reserved in case it uses space during the truncate (thank you * very much snapshotting). * - * And we need these to all be separate. The fact is we can use a lot of + * And we need these to be separate. The fact is we can use a lot of * space doing the truncate, and we have no earthly idea how much space * we will use, so we need the truncate reservation to be separate so it - * doesn't end up using space reserved for updating the inode or - * removing the orphan item. We also need to be able to stop the - * transaction and start a new one, which means we need to be able to - * update the inode several times, and we have no idea of knowing how - * many times that will be, so we can't just reserve 1 item for the - * entirety of the operation, so that has to be done separately as well. - * Then there is the orphan item, which does indeed need to be held on - * to for the whole operation, and we need nobody to touch this reserved - * space except the orphan code. + * doesn't end up using space reserved for updating the inode. We also + * need to be able to stop the transaction and start a new one, which + * means we need to be able to update the inode several times, and we + * have no idea of knowing how many times that will be, so we can't just + * reserve 1 item for the entirety of the operation, so that has to be + * done separately as well. * * So that leaves us with * - * 1) root->orphan_block_rsv - for the orphan deletion. - * 2) rsv - for the truncate reservation, which we will steal from the + * 1) rsv - for the truncate reservation, which we will steal from the * transaction reservation. - * 3) fs_info->trans_block_rsv - this will have 1 items worth left for + * 2) fs_info->trans_block_rsv - this will have 1 items worth left for * updating the inode. */ rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP); @@ -9345,13 +9291,6 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback) btrfs_ordered_update_i_size(inode, inode->i_size, NULL); } - if (ret == 0 && inode->i_nlink > 0) { - trans->block_rsv = root->orphan_block_rsv; - ret = btrfs_orphan_del(trans, BTRFS_I(inode)); - if (ret) - err = ret; - } - if (trans) { trans->block_rsv = &fs_info->trans_block_rsv; ret = btrfs_update_inode(trans, root, inode); -- 2.30.2