From 045d3967b6920b663fc010ad414ade1b24143bd1 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Wed, 18 Dec 2019 17:20:27 -0500 Subject: [PATCH 1/7] btrfs: rework arguments of btrfs_unlink_subvol btrfs_unlink_subvol takes the name of the dentry and the root objectid based on what kind of inode this is, either a real subvolume link or a empty one that we inherited as a snapshot. We need to fix how we unlink in the case for BTRFS_EMPTY_SUBVOL_DIR_OBJECTID in the future, so rework btrfs_unlink_subvol to just take the dentry and handle getting the right objectid given the type of inode this is. There is no functional change here, simply pushing the work into btrfs_unlink_subvol() proper. Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/inode.c | 46 ++++++++++++++++++++-------------------------- 1 file changed, 20 insertions(+), 26 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 5509c41a4f43..99631030d13c 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -4238,18 +4238,30 @@ out: } static int btrfs_unlink_subvol(struct btrfs_trans_handle *trans, - struct inode *dir, u64 objectid, - const char *name, int name_len) + struct inode *dir, struct dentry *dentry) { struct btrfs_root *root = BTRFS_I(dir)->root; + struct btrfs_inode *inode = BTRFS_I(d_inode(dentry)); struct btrfs_path *path; struct extent_buffer *leaf; struct btrfs_dir_item *di; struct btrfs_key key; + const char *name = dentry->d_name.name; + int name_len = dentry->d_name.len; u64 index; int ret; + u64 objectid; u64 dir_ino = btrfs_ino(BTRFS_I(dir)); + if (btrfs_ino(inode) == BTRFS_FIRST_FREE_OBJECTID) { + objectid = inode->root->root_key.objectid; + } else if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID) { + objectid = inode->location.objectid; + } else { + WARN_ON(1); + return -EINVAL; + } + path = btrfs_alloc_path(); if (!path) return -ENOMEM; @@ -4487,8 +4499,7 @@ int btrfs_delete_subvolume(struct inode *dir, struct dentry *dentry) btrfs_record_snapshot_destroy(trans, BTRFS_I(dir)); - ret = btrfs_unlink_subvol(trans, dir, dest->root_key.objectid, - dentry->d_name.name, dentry->d_name.len); + ret = btrfs_unlink_subvol(trans, dir, dentry); if (ret) { err = ret; btrfs_abort_transaction(trans, ret); @@ -4583,10 +4594,7 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry) return PTR_ERR(trans); if (unlikely(btrfs_ino(BTRFS_I(inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) { - err = btrfs_unlink_subvol(trans, dir, - BTRFS_I(inode)->location.objectid, - dentry->d_name.name, - dentry->d_name.len); + err = btrfs_unlink_subvol(trans, dir, dentry); goto out; } @@ -9536,7 +9544,6 @@ static int btrfs_rename_exchange(struct inode *old_dir, u64 new_ino = btrfs_ino(BTRFS_I(new_inode)); u64 old_idx = 0; u64 new_idx = 0; - u64 root_objectid; int ret; bool root_log_pinned = false; bool dest_log_pinned = false; @@ -9642,10 +9649,7 @@ static int btrfs_rename_exchange(struct inode *old_dir, /* src is a subvolume */ if (old_ino == BTRFS_FIRST_FREE_OBJECTID) { - root_objectid = BTRFS_I(old_inode)->root->root_key.objectid; - ret = btrfs_unlink_subvol(trans, old_dir, root_objectid, - old_dentry->d_name.name, - old_dentry->d_name.len); + ret = btrfs_unlink_subvol(trans, old_dir, old_dentry); } else { /* src is an inode */ ret = __btrfs_unlink_inode(trans, root, BTRFS_I(old_dir), BTRFS_I(old_dentry->d_inode), @@ -9661,10 +9665,7 @@ static int btrfs_rename_exchange(struct inode *old_dir, /* dest is a subvolume */ if (new_ino == BTRFS_FIRST_FREE_OBJECTID) { - root_objectid = BTRFS_I(new_inode)->root->root_key.objectid; - ret = btrfs_unlink_subvol(trans, new_dir, root_objectid, - new_dentry->d_name.name, - new_dentry->d_name.len); + ret = btrfs_unlink_subvol(trans, new_dir, new_dentry); } else { /* dest is an inode */ ret = __btrfs_unlink_inode(trans, dest, BTRFS_I(new_dir), BTRFS_I(new_dentry->d_inode), @@ -9862,7 +9863,6 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_inode = d_inode(new_dentry); struct inode *old_inode = d_inode(old_dentry); u64 index = 0; - u64 root_objectid; int ret; u64 old_ino = btrfs_ino(BTRFS_I(old_inode)); bool log_pinned = false; @@ -9970,10 +9970,7 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry, BTRFS_I(old_inode), 1); if (unlikely(old_ino == BTRFS_FIRST_FREE_OBJECTID)) { - root_objectid = BTRFS_I(old_inode)->root->root_key.objectid; - ret = btrfs_unlink_subvol(trans, old_dir, root_objectid, - old_dentry->d_name.name, - old_dentry->d_name.len); + ret = btrfs_unlink_subvol(trans, old_dir, old_dentry); } else { ret = __btrfs_unlink_inode(trans, root, BTRFS_I(old_dir), BTRFS_I(d_inode(old_dentry)), @@ -9992,10 +9989,7 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry, new_inode->i_ctime = current_time(new_inode); if (unlikely(btrfs_ino(BTRFS_I(new_inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) { - root_objectid = BTRFS_I(new_inode)->location.objectid; - ret = btrfs_unlink_subvol(trans, new_dir, root_objectid, - new_dentry->d_name.name, - new_dentry->d_name.len); + ret = btrfs_unlink_subvol(trans, new_dir, new_dentry); BUG_ON(new_inode->i_nlink == 0); } else { ret = btrfs_unlink_inode(trans, dest, BTRFS_I(new_dir), From d49d3287e74ffe55ae7430d1e795e5f9bf7359ea Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Wed, 18 Dec 2019 17:20:28 -0500 Subject: [PATCH 2/7] btrfs: fix invalid removal of root ref If we have the following sequence of events btrfs sub create A btrfs sub create A/B btrfs sub snap A C mkdir C/foo mv A/B C/foo rm -rf * We will end up with a transaction abort. The reason for this is because we create a root ref for B pointing to A. When we create a snapshot of C we still have B in our tree, but because the root ref points to A and not C we will make it appear to be empty. The problem happens when we move B into C. This removes the root ref for B pointing to A and adds a ref of B pointing to C. When we rmdir C we'll see that we have a ref to our root and remove the root ref, despite not actually matching our reference name. Now btrfs_del_root_ref() allowing this to work is a bug as well, however we know that this inode does not actually point to a root ref in the first place, so we shouldn't be calling btrfs_del_root_ref() in the first place and instead simply look up our dir index for this item and do the rest of the removal. CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/inode.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 99631030d13c..c70baafb2a39 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -4283,13 +4283,16 @@ static int btrfs_unlink_subvol(struct btrfs_trans_handle *trans, } btrfs_release_path(path); - ret = btrfs_del_root_ref(trans, objectid, root->root_key.objectid, - dir_ino, &index, name, name_len); - if (ret < 0) { - if (ret != -ENOENT) { - btrfs_abort_transaction(trans, ret); - goto out; - } + /* + * This is a placeholder inode for a subvolume we didn't have a + * reference to at the time of the snapshot creation. In the meantime + * we could have renamed the real subvol link into our snapshot, so + * depending on btrfs_del_root_ref to return -ENOENT here is incorret. + * Instead simply lookup the dir_index_item for this entry so we can + * remove it. Otherwise we know we have a ref to the root and we can + * call btrfs_del_root_ref, and it _shouldn't_ fail. + */ + if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID) { di = btrfs_search_dir_index_item(root, path, dir_ino, name, name_len); if (IS_ERR_OR_NULL(di)) { @@ -4304,8 +4307,16 @@ static int btrfs_unlink_subvol(struct btrfs_trans_handle *trans, leaf = path->nodes[0]; btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); index = key.offset; + btrfs_release_path(path); + } else { + ret = btrfs_del_root_ref(trans, objectid, + root->root_key.objectid, dir_ino, + &index, name, name_len); + if (ret) { + btrfs_abort_transaction(trans, ret); + goto out; + } } - btrfs_release_path(path); ret = btrfs_delete_delayed_dir_index(trans, BTRFS_I(dir), index); if (ret) { From 423a716cd7be16fb08690760691befe3be97d3fc Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Wed, 18 Dec 2019 17:20:29 -0500 Subject: [PATCH 3/7] btrfs: do not delete mismatched root refs btrfs_del_root_ref() will simply WARN_ON() if the ref doesn't match in any way, and then continue to delete the reference. This shouldn't happen, we have these values because there's more to the reference than the original root and the sub root. If any of these checks fail, return -ENOENT. CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/root-tree.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c index 3b17b647d002..612411c74550 100644 --- a/fs/btrfs/root-tree.c +++ b/fs/btrfs/root-tree.c @@ -376,11 +376,13 @@ again: leaf = path->nodes[0]; ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref); - - WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid); - WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len); ptr = (unsigned long)(ref + 1); - WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len)); + if ((btrfs_root_ref_dirid(leaf, ref) != dirid) || + (btrfs_root_ref_name_len(leaf, ref) != name_len) || + memcmp_extent_buffer(leaf, name, ptr, name_len)) { + err = -ENOENT; + goto out; + } *sequence = btrfs_root_ref_sequence(leaf, ref); ret = btrfs_del_item(trans, tree_root, path); From 26ef8493e1ab771cb01d27defca2fa1315dc3980 Mon Sep 17 00:00:00 2001 From: Johannes Thumshirn Date: Wed, 8 Jan 2020 21:07:32 +0900 Subject: [PATCH 4/7] btrfs: fix memory leak in qgroup accounting When running xfstests on the current btrfs I get the following splat from kmemleak: unreferenced object 0xffff88821b2404e0 (size 32): comm "kworker/u4:7", pid 26663, jiffies 4295283698 (age 8.776s) hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 10 ff fd 26 82 88 ff ff ...........&.... 10 ff fd 26 82 88 ff ff 20 ff fd 26 82 88 ff ff ...&.... ..&.... backtrace: [<00000000f94fd43f>] ulist_alloc+0x25/0x60 [btrfs] [<00000000fd023d99>] btrfs_find_all_roots_safe+0x41/0x100 [btrfs] [<000000008f17bd32>] btrfs_find_all_roots+0x52/0x70 [btrfs] [<00000000b7660afb>] btrfs_qgroup_rescan_worker+0x343/0x680 [btrfs] [<0000000058e66778>] btrfs_work_helper+0xac/0x1e0 [btrfs] [<00000000f0188930>] process_one_work+0x1cf/0x350 [<00000000af5f2f8e>] worker_thread+0x28/0x3c0 [<00000000b55a1add>] kthread+0x109/0x120 [<00000000f88cbd17>] ret_from_fork+0x35/0x40 This corresponds to: (gdb) l *(btrfs_find_all_roots_safe+0x41) 0x8d7e1 is in btrfs_find_all_roots_safe (fs/btrfs/backref.c:1413). 1408 1409 tmp = ulist_alloc(GFP_NOFS); 1410 if (!tmp) 1411 return -ENOMEM; 1412 *roots = ulist_alloc(GFP_NOFS); 1413 if (!*roots) { 1414 ulist_free(tmp); 1415 return -ENOMEM; 1416 } 1417 Following the lifetime of the allocated 'roots' ulist, it gets freed again in btrfs_qgroup_account_extent(). But this does not happen if the function is called with the 'BTRFS_FS_QUOTA_ENABLED' flag cleared, then btrfs_qgroup_account_extent() does a short leave and directly returns. Instead of directly returning we should jump to the 'out_free' in order to free all resources as expected. CC: stable@vger.kernel.org # 4.14+ Reviewed-by: Qu Wenruo Signed-off-by: Johannes Thumshirn [ add comment ] Signed-off-by: David Sterba --- fs/btrfs/qgroup.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index d4282e12f2a6..39fc8c3d3a75 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -2423,8 +2423,12 @@ int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, u64 bytenr, u64 nr_old_roots = 0; int ret = 0; + /* + * If quotas get disabled meanwhile, the resouces need to be freed and + * we can't just exit here. + */ if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)) - return 0; + goto out_free; if (new_roots) { if (!maybe_fs_roots(new_roots)) From 6282675e6708ec78518cc0e9ad1f1f73d7c5c53d Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Wed, 8 Jan 2020 13:12:00 +0800 Subject: [PATCH 5/7] btrfs: relocation: fix reloc_root lifespan and access [BUG] There are several different KASAN reports for balance + snapshot workloads. Involved call paths include: should_ignore_root+0x54/0xb0 [btrfs] build_backref_tree+0x11af/0x2280 [btrfs] relocate_tree_blocks+0x391/0xb80 [btrfs] relocate_block_group+0x3e5/0xa00 [btrfs] btrfs_relocate_block_group+0x240/0x4d0 [btrfs] btrfs_relocate_chunk+0x53/0xf0 [btrfs] btrfs_balance+0xc91/0x1840 [btrfs] btrfs_ioctl_balance+0x416/0x4e0 [btrfs] btrfs_ioctl+0x8af/0x3e60 [btrfs] do_vfs_ioctl+0x831/0xb10 create_reloc_root+0x9f/0x460 [btrfs] btrfs_reloc_post_snapshot+0xff/0x6c0 [btrfs] create_pending_snapshot+0xa9b/0x15f0 [btrfs] create_pending_snapshots+0x111/0x140 [btrfs] btrfs_commit_transaction+0x7a6/0x1360 [btrfs] btrfs_mksubvol+0x915/0x960 [btrfs] btrfs_ioctl_snap_create_transid+0x1d5/0x1e0 [btrfs] btrfs_ioctl_snap_create_v2+0x1d3/0x270 [btrfs] btrfs_ioctl+0x241b/0x3e60 [btrfs] do_vfs_ioctl+0x831/0xb10 btrfs_reloc_pre_snapshot+0x85/0xc0 [btrfs] create_pending_snapshot+0x209/0x15f0 [btrfs] create_pending_snapshots+0x111/0x140 [btrfs] btrfs_commit_transaction+0x7a6/0x1360 [btrfs] btrfs_mksubvol+0x915/0x960 [btrfs] btrfs_ioctl_snap_create_transid+0x1d5/0x1e0 [btrfs] btrfs_ioctl_snap_create_v2+0x1d3/0x270 [btrfs] btrfs_ioctl+0x241b/0x3e60 [btrfs] do_vfs_ioctl+0x831/0xb10 [CAUSE] All these call sites are only relying on root->reloc_root, which can undergo btrfs_drop_snapshot(), and since we don't have real refcount based protection to reloc roots, we can reach already dropped reloc root, triggering KASAN. [FIX] To avoid such access to unstable root->reloc_root, we should check BTRFS_ROOT_DEAD_RELOC_TREE bit first. This patch introduces wrappers that provide the correct way to check the bit with memory barriers protection. Most callers don't distinguish merged reloc tree and no reloc tree. The only exception is should_ignore_root(), as merged reloc tree can be ignored, while no reloc tree shouldn't. [CRITICAL SECTION ANALYSIS] Although test_bit()/set_bit()/clear_bit() doesn't imply a barrier, the DEAD_RELOC_TREE bit has extra help from transaction as a higher level barrier, the lifespan of root::reloc_root and DEAD_RELOC_TREE bit are: NULL: reloc_root is NULL PTR: reloc_root is not NULL 0: DEAD_RELOC_ROOT bit not set DEAD: DEAD_RELOC_ROOT bit set (NULL, 0) Initial state __ | /\ Section A btrfs_init_reloc_root() \/ | __ (PTR, 0) reloc_root initialized /\ | | btrfs_update_reloc_root() | Section B | | (PTR, DEAD) reloc_root has been merged \/ | __ === btrfs_commit_transaction() ==================== | /\ clean_dirty_subvols() | | | Section C (NULL, DEAD) reloc_root cleanup starts \/ | __ btrfs_drop_snapshot() /\ | | Section D (NULL, 0) Back to initial state \/ Every have_reloc_root() or test_bit(DEAD_RELOC_ROOT) caller holds transaction handle, so none of such caller can cross transaction boundary. In Section A, every caller just found no DEAD bit, and grab reloc_root. In the cross section A-B, caller may get no DEAD bit, but since reloc_root is still completely valid thus accessing reloc_root is completely safe. No test_bit() caller can cross the boundary of Section B and Section C. In Section C, every caller found the DEAD bit, so no one will access reloc_root. In the cross section C-D, either caller gets the DEAD bit set, avoiding access reloc_root no matter if it's safe or not. Or caller get the DEAD bit cleared, then access reloc_root, which is already NULL, nothing will be wrong. The memory write barriers are between the reloc_root updates and bit set/clear, the pairing read side is before test_bit. Reported-by: Zygo Blaxell Fixes: d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots") CC: stable@vger.kernel.org # 5.4+ Reviewed-by: Josef Bacik Signed-off-by: Qu Wenruo Reviewed-by: David Sterba [ barriers ] Signed-off-by: David Sterba --- fs/btrfs/relocation.c | 51 ++++++++++++++++++++++++++++++++++++++----- 1 file changed, 46 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index c58245797f30..da5abd62db22 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -517,6 +517,34 @@ static int update_backref_cache(struct btrfs_trans_handle *trans, return 1; } +static bool reloc_root_is_dead(struct btrfs_root *root) +{ + /* + * Pair with set_bit/clear_bit in clean_dirty_subvols and + * btrfs_update_reloc_root. We need to see the updated bit before + * trying to access reloc_root + */ + smp_rmb(); + if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state)) + return true; + return false; +} + +/* + * Check if this subvolume tree has valid reloc tree. + * + * Reloc tree after swap is considered dead, thus not considered as valid. + * This is enough for most callers, as they don't distinguish dead reloc root + * from no reloc root. But should_ignore_root() below is a special case. + */ +static bool have_reloc_root(struct btrfs_root *root) +{ + if (reloc_root_is_dead(root)) + return false; + if (!root->reloc_root) + return false; + return true; +} static int should_ignore_root(struct btrfs_root *root) { @@ -525,6 +553,10 @@ static int should_ignore_root(struct btrfs_root *root) if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state)) return 0; + /* This root has been merged with its reloc tree, we can ignore it */ + if (reloc_root_is_dead(root)) + return 1; + reloc_root = root->reloc_root; if (!reloc_root) return 0; @@ -1439,7 +1471,7 @@ int btrfs_init_reloc_root(struct btrfs_trans_handle *trans, * The subvolume has reloc tree but the swap is finished, no need to * create/update the dead reloc tree */ - if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state)) + if (reloc_root_is_dead(root)) return 0; if (root->reloc_root) { @@ -1478,8 +1510,7 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle *trans, struct btrfs_root_item *root_item; int ret; - if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state) || - !root->reloc_root) + if (!have_reloc_root(root)) goto out; reloc_root = root->reloc_root; @@ -1489,6 +1520,11 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle *trans, if (fs_info->reloc_ctl->merge_reloc_tree && btrfs_root_refs(root_item) == 0) { set_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state); + /* + * Mark the tree as dead before we change reloc_root so + * have_reloc_root will not touch it from now on. + */ + smp_wmb(); __del_reloc_root(reloc_root); } @@ -2201,6 +2237,11 @@ static int clean_dirty_subvols(struct reloc_control *rc) if (ret2 < 0 && !ret) ret = ret2; } + /* + * Need barrier to ensure clear_bit() only happens after + * root->reloc_root = NULL. Pairs with have_reloc_root. + */ + smp_wmb(); clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state); btrfs_put_fs_root(root); } else { @@ -4718,7 +4759,7 @@ void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending, struct btrfs_root *root = pending->root; struct reloc_control *rc = root->fs_info->reloc_ctl; - if (!root->reloc_root || !rc) + if (!rc || !have_reloc_root(root)) return; if (!rc->merge_reloc_tree) @@ -4752,7 +4793,7 @@ int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans, struct reloc_control *rc = root->fs_info->reloc_ctl; int ret; - if (!root->reloc_root || !rc) + if (!rc || !have_reloc_root(root)) return 0; rc = root->fs_info->reloc_ctl; From 5afe6ce748c1ea99e0d648153c05075e1ab93afb Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Thu, 16 Jan 2020 11:29:20 +0000 Subject: [PATCH 6/7] Btrfs: always copy scrub arguments back to user space If scrub returns an error we are not copying back the scrub arguments structure to user space. This prevents user space to know how much progress scrub has done if an error happened - this includes -ECANCELED which is returned when users ask for scrub to stop. A particular use case, which is used in btrfs-progs, is to resume scrub after it is canceled, in that case it relies on checking the progress from the scrub arguments structure and then use that progress in a call to resume scrub. So fix this by always copying the scrub arguments structure to user space, overwriting the value returned to user space with -EFAULT only if copying the structure failed to let user space know that either that copying did not happen, and therefore the structure is stale, or it happened partially and the structure is probably not valid and corrupt due to the partial copy. Reported-by: Graham Cobb Link: https://lore.kernel.org/linux-btrfs/d0a97688-78be-08de-ca7d-bcb4c7fb397e@cobb.uk.net/ Fixes: 06fe39ab15a6a4 ("Btrfs: do not overwrite scrub error with fault error in scrub ioctl") CC: stable@vger.kernel.org # 5.1+ Reviewed-by: Johannes Thumshirn Reviewed-by: Qu Wenruo Tested-by: Graham Cobb Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/ioctl.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 18e328ce4b54..12ae31e1813e 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -4252,7 +4252,19 @@ static long btrfs_ioctl_scrub(struct file *file, void __user *arg) &sa->progress, sa->flags & BTRFS_SCRUB_READONLY, 0); - if (ret == 0 && copy_to_user(arg, sa, sizeof(*sa))) + /* + * Copy scrub args to user space even if btrfs_scrub_dev() returned an + * error. This is important as it allows user space to know how much + * progress scrub has done. For example, if scrub is canceled we get + * -ECANCELED from btrfs_scrub_dev() and return that error back to user + * space. Later user space can inspect the progress from the structure + * btrfs_ioctl_scrub_args and resume scrub from where it left off + * previously (btrfs-progs does this). + * If we fail to copy the btrfs_ioctl_scrub_args structure to user space + * then return -EFAULT to signal the structure was not copied or it may + * be corrupt and unreliable due to a partial copy. + */ + if (copy_to_user(arg, sa, sizeof(*sa))) ret = -EFAULT; if (!(sa->flags & BTRFS_SCRUB_READONLY)) From b35cf1f0bf1f2b0b193093338414b9bd63b29015 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 10 Jan 2020 11:11:24 -0500 Subject: [PATCH 7/7] btrfs: check rw_devices, not num_devices for balance The fstest btrfs/154 reports [ 8675.381709] BTRFS: Transaction aborted (error -28) [ 8675.383302] WARNING: CPU: 1 PID: 31900 at fs/btrfs/block-group.c:2038 btrfs_create_pending_block_groups+0x1e0/0x1f0 [btrfs] [ 8675.390925] CPU: 1 PID: 31900 Comm: btrfs Not tainted 5.5.0-rc6-default+ #935 [ 8675.392780] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014 [ 8675.395452] RIP: 0010:btrfs_create_pending_block_groups+0x1e0/0x1f0 [btrfs] [ 8675.402672] RSP: 0018:ffffb2090888fb00 EFLAGS: 00010286 [ 8675.404413] RAX: 0000000000000000 RBX: ffff92026dfa91c8 RCX: 0000000000000001 [ 8675.406609] RDX: 0000000000000000 RSI: ffffffff8e100899 RDI: ffffffff8e100971 [ 8675.408775] RBP: ffff920247c61660 R08: 0000000000000000 R09: 0000000000000000 [ 8675.410978] R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffe4 [ 8675.412647] R13: ffff92026db74000 R14: ffff920247c616b8 R15: ffff92026dfbc000 [ 8675.413994] FS: 00007fd5e57248c0(0000) GS:ffff92027d800000(0000) knlGS:0000000000000000 [ 8675.416146] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 8675.417833] CR2: 0000564aa51682d8 CR3: 000000006dcbc004 CR4: 0000000000160ee0 [ 8675.419801] Call Trace: [ 8675.420742] btrfs_start_dirty_block_groups+0x355/0x480 [btrfs] [ 8675.422600] btrfs_commit_transaction+0xc8/0xaf0 [btrfs] [ 8675.424335] reset_balance_state+0x14a/0x190 [btrfs] [ 8675.425824] btrfs_balance.cold+0xe7/0x154 [btrfs] [ 8675.427313] ? kmem_cache_alloc_trace+0x235/0x2c0 [ 8675.428663] btrfs_ioctl_balance+0x298/0x350 [btrfs] [ 8675.430285] btrfs_ioctl+0x466/0x2550 [btrfs] [ 8675.431788] ? mem_cgroup_charge_statistics+0x51/0xf0 [ 8675.433487] ? mem_cgroup_commit_charge+0x56/0x400 [ 8675.435122] ? do_raw_spin_unlock+0x4b/0xc0 [ 8675.436618] ? _raw_spin_unlock+0x1f/0x30 [ 8675.438093] ? __handle_mm_fault+0x499/0x740 [ 8675.439619] ? do_vfs_ioctl+0x56e/0x770 [ 8675.441034] do_vfs_ioctl+0x56e/0x770 [ 8675.442411] ksys_ioctl+0x3a/0x70 [ 8675.443718] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 8675.445333] __x64_sys_ioctl+0x16/0x20 [ 8675.446705] do_syscall_64+0x50/0x210 [ 8675.448059] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 8675.479187] BTRFS: error (device vdb) in btrfs_create_pending_block_groups:2038: errno=-28 No space left We now use btrfs_can_overcommit() to see if we can flip a block group read only. Before this would fail because we weren't taking into account the usable un-allocated space for allocating chunks. With my patches we were allowed to do the balance, which is technically correct. The test is trying to start balance on degraded mount. So now we're trying to allocate a chunk and cannot because we want to allocate a RAID1 chunk, but there's only 1 device that's available for usage. This results in an ENOSPC. But we shouldn't even be making it this far, we don't have enough devices to restripe. The problem is we're using btrfs_num_devices(), that also includes missing devices. That's not actually what we want, we need to use rw_devices. The chunk_mutex is not needed here, rw_devices changes only in device add, remove or replace, all are excluded by EXCL_OP mechanism. Fixes: e4d8ec0f65b9 ("Btrfs: implement online profile changing") CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Josef Bacik Reviewed-by: David Sterba [ add stacktrace, update changelog, drop chunk_mutex ] Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index a6d3f08bfff3..9b78e720c697 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3881,7 +3881,11 @@ int btrfs_balance(struct btrfs_fs_info *fs_info, } } - num_devices = btrfs_num_devices(fs_info); + /* + * rw_devices will not change at the moment, device add/delete/replace + * are excluded by EXCL_OP + */ + num_devices = fs_info->fs_devices->rw_devices; /* * SINGLE profile on-disk has no profile bit, but in-memory we have a