On Fri, Mar 2, 2018 at 7:00 PM, Liu Bo <bo.li....@oracle.com> wrote: > On Fri, Mar 02, 2018 at 11:29:33AM -0700, Liu Bo wrote: >> On Wed, Feb 28, 2018 at 03:56:10PM +0000, fdman...@kernel.org wrote: >> > From: Filipe Manana <fdman...@suse.com> >> > >> > If we have a file with 2 (or more) hard links in the same directory, >> > remove one of the hard links, create a new file (or link an existing file) >> > in the same directory with the name of the removed hard link, and then >> > finally fsync the new file, we end up with a log that fails to replay, >> > causing a mount failure. >> > >> > Example: >> > >> > $ mkfs.btrfs -f /dev/sdb >> > $ mount /dev/sdb /mnt >> > >> > $ mkdir /mnt/testdir >> > $ touch /mnt/testdir/foo >> > $ ln /mnt/testdir/foo /mnt/testdir/bar >> > >> > $ sync >> > >> > $ unlink /mnt/testdir/bar >> > $ touch /mnt/testdir/bar > > So here, "unlink & touch" similar to rename, therefore we could also > be conservative and set /mnt/testdir 's last_unlink_trans to force to > commit transaction.
That would cause any fsync on any file inside the directory to result in a full transaction commit. We had in the past more "exotic" scenarios with renames and creating new files with the same old name where the initial solution was just that, forcing a full commit [1], just to find out later that it caused big performance drop on real workloads [2]. That's why I'm avoiding it, even because fsync'ing any file in the directory (existing or new) isn't uncommon at all. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=56f23fdbb600e6087db7b009775b95ce07cc3195 [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=44f714dae50a2e795d3268a6831762aa6fa54f55 thanks > > Thanks, > > -liubo > >> > $ xfs_io -c "fsync" /mnt/testdir/bar >> > >> > <power failure> >> > >> > $ mount /dev/sdb /mnt >> > mount: mount(2) failed: /mnt: No such file or directory >> > >> > When replaying the log, for that example, we also see the following in >> > dmesg/syslog: >> > >> > [71813.671307] BTRFS info (device dm-0): failed to delete reference to >> > bar, inode 258 parent 257 >> > [71813.674204] ------------[ cut here ]------------ >> > [71813.675694] BTRFS: Transaction aborted (error -2) >> > [71813.677236] WARNING: CPU: 1 PID: 13231 at fs/btrfs/inode.c:4128 >> > __btrfs_unlink_inode+0x17b/0x355 [btrfs] >> > [71813.679669] Modules linked in: btrfs xfs f2fs dm_flakey dm_mod dax >> > ghash_clmulni_intel ppdev pcbc aesni_intel aes_x86_64 crypto_simd cryptd >> > glue_helper evdev psmouse i2c_piix4 parport_pc i2c_core pcspkr sg >> > serio_raw parport button sunrpc loop autofs4 ext4 crc16 mbcache jbd2 >> > zstd_decompress zstd_compress xxhash raid10 raid456 async_raid6_recov >> > async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c >> > crc32c_generic raid1 raid0 multipath linear md_mod ata_generic sd_mod >> > virtio_scsi ata_piix libata virtio_pci virtio_ring crc32c_intel floppy >> > virtio e1000 scsi_mod [last unloaded: btrfs] >> > [71813.679669] CPU: 1 PID: 13231 Comm: mount Tainted: G W >> > 4.15.0-rc9-btrfs-next-56+ #1 >> > [71813.679669] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), >> > BIOS rel-1.10.2-0-g5f4c7b1-prebuilt.qemu-project.org 04/01/2014 >> > [71813.679669] RIP: 0010:__btrfs_unlink_inode+0x17b/0x355 [btrfs] >> > [71813.679669] RSP: 0018:ffffc90001cef738 EFLAGS: 00010286 >> > [71813.679669] RAX: 0000000000000025 RBX: ffff880217ce4708 RCX: >> > 0000000000000001 >> > [71813.679669] RDX: 0000000000000000 RSI: ffffffff81c14bae RDI: >> > 00000000ffffffff >> > [71813.679669] RBP: ffffc90001cef7c0 R08: 0000000000000001 R09: >> > 0000000000000001 >> > [71813.679669] R10: ffffc90001cef5e0 R11: ffffffff8343f007 R12: >> > ffff880217d474c8 >> > [71813.679669] R13: 00000000fffffffe R14: ffff88021ccf1548 R15: >> > 0000000000000101 >> > [71813.679669] FS: 00007f7cee84c480(0000) GS:ffff88023fc80000(0000) >> > knlGS:0000000000000000 >> > [71813.679669] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> > [71813.679669] CR2: 00007f7cedc1abf9 CR3: 00000002354b4003 CR4: >> > 00000000001606e0 >> > [71813.679669] Call Trace: >> > [71813.679669] btrfs_unlink_inode+0x17/0x41 [btrfs] >> > [71813.679669] drop_one_dir_item+0xfa/0x131 [btrfs] >> > [71813.679669] add_inode_ref+0x71e/0x851 [btrfs] >> > [71813.679669] ? __lock_is_held+0x39/0x71 >> > [71813.679669] ? replay_one_buffer+0x53/0x53a [btrfs] >> > [71813.679669] replay_one_buffer+0x4a4/0x53a [btrfs] >> > [71813.679669] ? rcu_read_unlock+0x3a/0x57 >> > [71813.679669] ? __lock_is_held+0x39/0x71 >> > [71813.679669] walk_up_log_tree+0x101/0x1d2 [btrfs] >> > [71813.679669] walk_log_tree+0xad/0x188 [btrfs] >> > [71813.679669] btrfs_recover_log_trees+0x1fa/0x31e [btrfs] >> > [71813.679669] ? replay_one_extent+0x544/0x544 [btrfs] >> > [71813.679669] open_ctree+0x1cf6/0x2209 [btrfs] >> > [71813.679669] btrfs_mount_root+0x368/0x482 [btrfs] >> > [71813.679669] ? trace_hardirqs_on_caller+0x14c/0x1a6 >> > [71813.679669] ? __lockdep_init_map+0x176/0x1c2 >> > [71813.679669] ? mount_fs+0x64/0x10b >> > [71813.679669] mount_fs+0x64/0x10b >> > [71813.679669] vfs_kern_mount+0x68/0xce >> > [71813.679669] btrfs_mount+0x13e/0x772 [btrfs] >> > [71813.679669] ? trace_hardirqs_on_caller+0x14c/0x1a6 >> > [71813.679669] ? __lockdep_init_map+0x176/0x1c2 >> > [71813.679669] ? mount_fs+0x64/0x10b >> > [71813.679669] mount_fs+0x64/0x10b >> > [71813.679669] vfs_kern_mount+0x68/0xce >> > [71813.679669] do_mount+0x6e5/0x973 >> > [71813.679669] ? memdup_user+0x3e/0x5c >> > [71813.679669] SyS_mount+0x72/0x98 >> > [71813.679669] entry_SYSCALL_64_fastpath+0x1e/0x8b >> > [71813.679669] RIP: 0033:0x7f7cedf150ba >> > [71813.679669] RSP: 002b:00007ffca71da688 EFLAGS: 00000206 >> > [71813.679669] Code: 7f a0 e8 51 0c fd ff 48 8b 43 50 f0 0f ba a8 30 2c >> > 00 00 02 72 17 41 83 fd fb 74 11 44 89 ee 48 c7 c7 7d 11 7f a0 e8 38 f5 8d >> > e0 <0f> ff 44 89 e9 ba 20 10 00 00 eb 4d 48 8b 4d b0 48 8b 75 88 4c >> > [71813.679669] ---[ end trace 83bd473fc5b4663b ]--- >> > [71813.854764] BTRFS: error (device dm-0) in __btrfs_unlink_inode:4128: >> > errno=-2 No such entry >> > [71813.886994] BTRFS: error (device dm-0) in btrfs_replay_log:2307: >> > errno=-2 No such entry (Failed to recover log tree) >> > [71813.903357] BTRFS error (device dm-0): cleaner transaction attach >> > returned -30 >> > [71814.128078] BTRFS error (device dm-0): open_ctree failed >> > >> > This happens because the log has inode reference items for both inode 258 >> > (the first file we created) and inode 259 (the second file created), and >> > when processing the reference item for inode 258, we replace the >> > corresponding item in the subvolume tree (which has two names, "foo" and >> > "bar") witht he one in the log (which only has one name, "foo") without >> > removing the corresponding dir index keys from the parent directory. >> > Later, when processing the inode reference item for inode 259, which has >> > a name of "bar" associated to it, we notice that dir index entries exist >> > for that name and for a different inode, so we attempt to unlink that >> > name, which fails because the inode reference item for inode 258 no longer >> > has the name "bar" associated to it, making a call to btrfs_unlink_inode() >> > fail with a -ENOENT error. >> > >> > Fix this by unlinking all the names in an inode reference item from a >> > subvolume tree that are not present in the inode reference item found in >> > the log tree, before overwriting it with the item from the log tree. >> >> Since the order during replaying is INODE_ITEM then DIR_INDEX then >> other types, in this particular case, can we fix the problem by also >> logging the parent so that we have the correct DIR_INDEX? >> >> With DIR_INDEX, the problem would be fixed simpler, wouldn't it? >> >> Thanks, >> >> -liubo >> > >> > Signed-off-by: Filipe Manana <fdman...@suse.com> >> > --- >> > fs/btrfs/ctree.h | 5 ++- >> > fs/btrfs/inode-item.c | 44 ++++++++++++-------- >> > fs/btrfs/tree-log.c | 112 >> > ++++++++++++++++++++++++++++++++++++++++++++++++-- >> > 3 files changed, 139 insertions(+), 22 deletions(-) >> > >> > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h >> > index 1a462ab85c49..5d33478bc704 100644 >> > --- a/fs/btrfs/ctree.h >> > +++ b/fs/btrfs/ctree.h >> > @@ -3095,7 +3095,10 @@ btrfs_lookup_inode_extref(struct btrfs_trans_handle >> > *trans, >> > u64 inode_objectid, u64 ref_objectid, int ins_len, >> > int cow); >> > >> > -int btrfs_find_name_in_ext_backref(struct btrfs_path *path, >> > +int btrfs_find_name_in_backref(struct extent_buffer *leaf, int slot, >> > + const char *name, >> > + int name_len, struct btrfs_inode_ref **ref_ret); >> > +int btrfs_find_name_in_ext_backref(struct extent_buffer *leaf, int slot, >> > u64 ref_objectid, const char *name, >> > int name_len, >> > struct btrfs_inode_extref **extref_ret); >> > diff --git a/fs/btrfs/inode-item.c b/fs/btrfs/inode-item.c >> > index 39c968f80157..65e1a76bf755 100644 >> > --- a/fs/btrfs/inode-item.c >> > +++ b/fs/btrfs/inode-item.c >> > @@ -22,10 +22,10 @@ >> > #include "transaction.h" >> > #include "print-tree.h" >> > >> > -static int find_name_in_backref(struct btrfs_path *path, const char *name, >> > - int name_len, struct btrfs_inode_ref **ref_ret) >> > +int btrfs_find_name_in_backref(struct extent_buffer *leaf, int slot, >> > + const char *name, >> > + int name_len, struct btrfs_inode_ref **ref_ret) >> > { >> > - struct extent_buffer *leaf; >> > struct btrfs_inode_ref *ref; >> > unsigned long ptr; >> > unsigned long name_ptr; >> > @@ -33,9 +33,8 @@ static int find_name_in_backref(struct btrfs_path *path, >> > const char *name, >> > u32 cur_offset = 0; >> > int len; >> > >> > - leaf = path->nodes[0]; >> > - item_size = btrfs_item_size_nr(leaf, path->slots[0]); >> > - ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); >> > + item_size = btrfs_item_size_nr(leaf, slot); >> > + ptr = btrfs_item_ptr_offset(leaf, slot); >> > while (cur_offset < item_size) { >> > ref = (struct btrfs_inode_ref *)(ptr + cur_offset); >> > len = btrfs_inode_ref_name_len(leaf, ref); >> > @@ -44,18 +43,19 @@ static int find_name_in_backref(struct btrfs_path >> > *path, const char *name, >> > if (len != name_len) >> > continue; >> > if (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0) >> > { >> > - *ref_ret = ref; >> > + if (ref_ret) >> > + *ref_ret = ref; >> > return 1; >> > } >> > } >> > return 0; >> > } >> > >> > -int btrfs_find_name_in_ext_backref(struct btrfs_path *path, u64 >> > ref_objectid, >> > +int btrfs_find_name_in_ext_backref(struct extent_buffer *leaf, int slot, >> > + u64 ref_objectid, >> > const char *name, int name_len, >> > struct btrfs_inode_extref **extref_ret) >> > { >> > - struct extent_buffer *leaf; >> > struct btrfs_inode_extref *extref; >> > unsigned long ptr; >> > unsigned long name_ptr; >> > @@ -63,9 +63,8 @@ int btrfs_find_name_in_ext_backref(struct btrfs_path >> > *path, u64 ref_objectid, >> > u32 cur_offset = 0; >> > int ref_name_len; >> > >> > - leaf = path->nodes[0]; >> > - item_size = btrfs_item_size_nr(leaf, path->slots[0]); >> > - ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); >> > + item_size = btrfs_item_size_nr(leaf, slot); >> > + ptr = btrfs_item_ptr_offset(leaf, slot); >> > >> > /* >> > * Search all extended backrefs in this item. We're only >> > @@ -113,7 +112,9 @@ btrfs_lookup_inode_extref(struct btrfs_trans_handle >> > *trans, >> > return ERR_PTR(ret); >> > if (ret > 0) >> > return NULL; >> > - if (!btrfs_find_name_in_ext_backref(path, ref_objectid, name, >> > name_len, &extref)) >> > + if (!btrfs_find_name_in_ext_backref(path->nodes[0], path->slots[0], >> > + ref_objectid, name, name_len, >> > + &extref)) >> > return NULL; >> > return extref; >> > } >> > @@ -155,7 +156,8 @@ static int btrfs_del_inode_extref(struct >> > btrfs_trans_handle *trans, >> > * This should always succeed so error here will make the FS >> > * readonly. >> > */ >> > - if (!btrfs_find_name_in_ext_backref(path, ref_objectid, >> > + if (!btrfs_find_name_in_ext_backref(path->nodes[0], path->slots[0], >> > + ref_objectid, >> > name, name_len, &extref)) { >> > btrfs_handle_fs_error(root->fs_info, -ENOENT, NULL); >> > ret = -EROFS; >> > @@ -225,7 +227,8 @@ int btrfs_del_inode_ref(struct btrfs_trans_handle >> > *trans, >> > } else if (ret < 0) { >> > goto out; >> > } >> > - if (!find_name_in_backref(path, name, name_len, &ref)) { >> > + if (!btrfs_find_name_in_backref(path->nodes[0], path->slots[0], >> > + name, name_len, &ref)) { >> > ret = -ENOENT; >> > search_ext_refs = 1; >> > goto out; >> > @@ -293,7 +296,9 @@ static int btrfs_insert_inode_extref(struct >> > btrfs_trans_handle *trans, >> > ret = btrfs_insert_empty_item(trans, root, path, &key, >> > ins_len); >> > if (ret == -EEXIST) { >> > - if (btrfs_find_name_in_ext_backref(path, ref_objectid, >> > + if (btrfs_find_name_in_ext_backref(path->nodes[0], >> > + path->slots[0], >> > + ref_objectid, >> > name, name_len, NULL)) >> > goto out; >> > >> > @@ -351,7 +356,8 @@ int btrfs_insert_inode_ref(struct btrfs_trans_handle >> > *trans, >> > if (ret == -EEXIST) { >> > u32 old_size; >> > >> > - if (find_name_in_backref(path, name, name_len, &ref)) >> > + if (btrfs_find_name_in_backref(path->nodes[0], path->slots[0], >> > + name, name_len, &ref)) >> > goto out; >> > >> > old_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]); >> > @@ -365,7 +371,9 @@ int btrfs_insert_inode_ref(struct btrfs_trans_handle >> > *trans, >> > ret = 0; >> > } else if (ret < 0) { >> > if (ret == -EOVERFLOW) { >> > - if (find_name_in_backref(path, name, name_len, &ref)) >> > + if (btrfs_find_name_in_backref(path->nodes[0], >> > + path->slots[0], >> > + name, name_len, &ref)) >> > ret = -EEXIST; >> > else >> > ret = -EMLINK; >> > diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c >> > index 411a022489e4..fd573816f461 100644 >> > --- a/fs/btrfs/tree-log.c >> > +++ b/fs/btrfs/tree-log.c >> > @@ -966,7 +966,9 @@ static noinline int backref_in_log(struct btrfs_root >> > *log, >> > ptr = btrfs_item_ptr_offset(path->nodes[0], path->slots[0]); >> > >> > if (key->type == BTRFS_INODE_EXTREF_KEY) { >> > - if (btrfs_find_name_in_ext_backref(path, ref_objectid, >> > + if (btrfs_find_name_in_ext_backref(path->nodes[0], >> > + path->slots[0], >> > + ref_objectid, >> > name, namelen, NULL)) >> > match = 1; >> > >> > @@ -1190,7 +1192,8 @@ static int extref_get_fields(struct extent_buffer >> > *eb, unsigned long ref_ptr, >> > read_extent_buffer(eb, *name, (unsigned long)&extref->name, >> > *namelen); >> > >> > - *index = btrfs_inode_extref_index(eb, extref); >> > + if (index) >> > + *index = btrfs_inode_extref_index(eb, extref); >> > if (parent_objectid) >> > *parent_objectid = btrfs_inode_extref_parent(eb, extref); >> > >> > @@ -1211,12 +1214,102 @@ static int ref_get_fields(struct extent_buffer >> > *eb, unsigned long ref_ptr, >> > >> > read_extent_buffer(eb, *name, (unsigned long)(ref + 1), *namelen); >> > >> > - *index = btrfs_inode_ref_index(eb, ref); >> > + if (index) >> > + *index = btrfs_inode_ref_index(eb, ref); >> > >> > return 0; >> > } >> > >> > /* >> > + * Take an inode reference item from the log tree and iterate all names >> > from the >> > + * inode reference item in the subvolume tree with the same key (if it >> > exists). >> > + * For any name that is not in the inode reference item from the log >> > tree, do a >> > + * proper unlink of that name (that is, remove its entry from the inode >> > + * reference item and both dir index keys). >> > + */ >> > +static int unlink_old_inode_refs(struct btrfs_trans_handle *trans, >> > + struct btrfs_root *root, >> > + struct btrfs_path *path, >> > + struct btrfs_inode *inode, >> > + struct extent_buffer *log_eb, >> > + int log_slot, >> > + struct btrfs_key *key) >> > +{ >> > + int ret; >> > + unsigned long ref_ptr; >> > + unsigned long ref_end; >> > + struct extent_buffer *eb; >> > + >> > +again: >> > + btrfs_release_path(path); >> > + ret = btrfs_search_slot(NULL, root, key, path, 0, 0); >> > + if (ret > 0) { >> > + ret = 0; >> > + goto out; >> > + } >> > + if (ret < 0) >> > + goto out; >> > + >> > + eb = path->nodes[0]; >> > + ref_ptr = btrfs_item_ptr_offset(eb, path->slots[0]); >> > + ref_end = ref_ptr + btrfs_item_size_nr(eb, path->slots[0]); >> > + while (ref_ptr < ref_end) { >> > + char *name = NULL; >> > + int namelen; >> > + u64 parent_id; >> > + >> > + if (key->type == BTRFS_INODE_EXTREF_KEY) { >> > + ret = extref_get_fields(eb, ref_ptr, &namelen, &name, >> > + NULL, &parent_id); >> > + } else { >> > + parent_id = key->offset; >> > + ret = ref_get_fields(eb, ref_ptr, &namelen, &name, >> > + NULL); >> > + } >> > + if (ret) >> > + goto out; >> > + >> > + if (key->type == BTRFS_INODE_EXTREF_KEY) >> > + ret = btrfs_find_name_in_ext_backref(log_eb, log_slot, >> > + parent_id, name, >> > + namelen, NULL); >> > + else >> > + ret = btrfs_find_name_in_backref(log_eb, log_slot, >> > name, >> > + namelen, NULL); >> > + >> > + if (!ret) { >> > + struct inode *dir; >> > + >> > + btrfs_release_path(path); >> > + dir = read_one_inode(root, parent_id); >> > + if (!dir) { >> > + ret = -ENOENT; >> > + kfree(name); >> > + goto out; >> > + } >> > + ret = btrfs_unlink_inode(trans, root, BTRFS_I(dir), >> > + inode, name, namelen); >> > + kfree(name); >> > + iput(dir); >> > + if (ret) >> > + goto out; >> > + goto again; >> > + } >> > + >> > + kfree(name); >> > + ref_ptr += namelen; >> > + if (key->type == BTRFS_INODE_EXTREF_KEY) >> > + ref_ptr += sizeof(struct btrfs_inode_extref); >> > + else >> > + ref_ptr += sizeof(struct btrfs_inode_ref); >> > + } >> > + ret = 0; >> > + out: >> > + btrfs_release_path(path); >> > + return ret; >> > +} >> > + >> > +/* >> > * replay one inode back reference item found in the log tree. >> > * eb, slot and key refer to the buffer and key found in the log tree. >> > * root is the destination we are replaying into, and path is for temp >> > @@ -1344,6 +1437,19 @@ static noinline int add_inode_ref(struct >> > btrfs_trans_handle *trans, >> > } >> > } >> > >> > + /* >> > + * Before we overwrite the inode reference item in the subvolume tree >> > + * with the item from the log tree, we must unlink all names from the >> > + * parent directory that are in the subvolume's tree inode reference >> > + * item, otherwise we end up with an inconsistent subvolume tree where >> > + * dir index entries exist for a name but there is no inode reference >> > + * item with the same name. >> > + */ >> > + ret = unlink_old_inode_refs(trans, root, path, BTRFS_I(inode), eb, >> > slot, >> > + key); >> > + if (ret) >> > + goto out; >> > + >> > /* finally write the back reference in the inode */ >> > ret = overwrite_item(trans, root, path, eb, slot, key); >> > out: >> > -- >> > 2.11.0 >> > >> > -- >> > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >> > the body of a message to majord...@vger.kernel.org >> > More majordomo info at http://vger.kernel.org/majordomo-info.html >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >> the body of a message to majord...@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
