| Message ID | a8e439ad35a37fdd1a245299aa261bc49dcc4aa9.1603828718.git.boris@bur.io (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v5,01/10] btrfs: lift rw mount setup from mount and remount | expand |
On 10/27/20 5:07 PM, Boris Burkov wrote: > Mounting rw and remounting from ro to rw naturally share invariants and > functionality which result in a correctly setup rw filesystem. Luckily, > there is even a strong unity in the code which implements them. In > mount's open_ctree, these operations mostly happen after an early return > for ro file systems, and in remount, they happen in a section devoted to > remounting ro->rw, after some remount specific validation passes. > > However, there are unfortunately a few differences. There are small > deviations in the order of some of the operations, remount does not > cleanup orphan inodes in root_tree or fs_tree, remount does not create > the free space tree, and remount does not handle "one-shot" mount > options like clear_cache and uuid tree rescan. > > Since we want to add building the free space tree to remount, and since > it is possible to leak orphans on a filesystem mounted as ro then > remounted rw (common for the root filesystem when booting), we would > benefit from unifying the logic between the two codepaths. > > This patch only lifts the existing common functionality, and leaves a > natural path for fixing the discrepancies. > > Signed-off-by: Boris Burkov <boris@bur.io> > --- > fs/btrfs/disk-io.c | 93 ++++++++++++++++++++++++++-------------------- > fs/btrfs/disk-io.h | 1 + > fs/btrfs/super.c | 37 +++--------------- > 3 files changed, 60 insertions(+), 71 deletions(-) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index 3d39f5d47ad3..bff7a3a7be18 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -2814,6 +2814,53 @@ static int btrfs_check_uuid_tree(struct btrfs_fs_info *fs_info) > return 0; > } > > +/* > + * Mounting logic specific to read-write file systems. Shared by open_ctree > + * and btrfs_remount when remounting from read-only to read-write. > + */ > +int btrfs_mount_rw(struct btrfs_fs_info *fs_info) > +{ > + int ret; > + > + ret = btrfs_cleanup_fs_roots(fs_info); > + if (ret) > + goto out; > + > + mutex_lock(&fs_info->cleaner_mutex); > + ret = btrfs_recover_relocation(fs_info->tree_root); > + mutex_unlock(&fs_info->cleaner_mutex); > + if (ret < 0) { > + btrfs_warn(fs_info, "failed to recover relocation: %d", ret); > + goto out; > + } > + > + ret = btrfs_resume_balance_async(fs_info); > + if (ret) > + goto out; > + > + ret = btrfs_resume_dev_replace_async(fs_info); > + if (ret) { > + btrfs_warn(fs_info, "failed to resume dev_replace"); > + goto out; > + } > + > + btrfs_qgroup_rescan_resume(fs_info); > + > + if (!fs_info->uuid_root) { > + btrfs_info(fs_info, "creating UUID tree"); > + ret = btrfs_create_uuid_tree(fs_info); > + if (ret) { > + btrfs_warn(fs_info, > + "failed to create the UUID tree %d", > + ret); > + goto out; > + } > + } > + > +out: > + return ret; > +} > + > int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_devices, > char *options) > { > @@ -3218,22 +3265,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device > if (ret) > goto fail_qgroup; > > - if (!sb_rdonly(sb)) { > - ret = btrfs_cleanup_fs_roots(fs_info); > - if (ret) > - goto fail_qgroup; > - > - mutex_lock(&fs_info->cleaner_mutex); > - ret = btrfs_recover_relocation(tree_root); > - mutex_unlock(&fs_info->cleaner_mutex); > - if (ret < 0) { > - btrfs_warn(fs_info, "failed to recover relocation: %d", > - ret); > - err = -EINVAL; > - goto fail_qgroup; > - } > - } > - > fs_info->fs_root = btrfs_get_fs_root(fs_info, BTRFS_FS_TREE_OBJECTID, true); > if (IS_ERR(fs_info->fs_root)) { > err = PTR_ERR(fs_info->fs_root); > @@ -3286,35 +3317,17 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device > } > up_read(&fs_info->cleanup_work_sem); > > - ret = btrfs_resume_balance_async(fs_info); > - if (ret) { > - btrfs_warn(fs_info, "failed to resume balance: %d", ret); > - close_ctree(fs_info); > - return ret; > - } > - > - ret = btrfs_resume_dev_replace_async(fs_info); > + btrfs_discard_resume(fs_info); > + ret = btrfs_mount_rw(fs_info); You've swapped the order of discard_resume and the mount_rw stuff, which can be problematic because the tree log blocks will be marked as free, so we could discard them while replaying the log. The discard_resume needs to be moved. I'd even argue it needs to not be resumed unless we're rw, but I haven't looked at the code that closely. Thanks, Josef
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 3d39f5d47ad3..bff7a3a7be18 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2814,6 +2814,53 @@ static int btrfs_check_uuid_tree(struct btrfs_fs_info *fs_info) return 0; } +/* + * Mounting logic specific to read-write file systems. Shared by open_ctree + * and btrfs_remount when remounting from read-only to read-write. + */ +int btrfs_mount_rw(struct btrfs_fs_info *fs_info) +{ + int ret; + + ret = btrfs_cleanup_fs_roots(fs_info); + if (ret) + goto out; + + mutex_lock(&fs_info->cleaner_mutex); + ret = btrfs_recover_relocation(fs_info->tree_root); + mutex_unlock(&fs_info->cleaner_mutex); + if (ret < 0) { + btrfs_warn(fs_info, "failed to recover relocation: %d", ret); + goto out; + } + + ret = btrfs_resume_balance_async(fs_info); + if (ret) + goto out; + + ret = btrfs_resume_dev_replace_async(fs_info); + if (ret) { + btrfs_warn(fs_info, "failed to resume dev_replace"); + goto out; + } + + btrfs_qgroup_rescan_resume(fs_info); + + if (!fs_info->uuid_root) { + btrfs_info(fs_info, "creating UUID tree"); + ret = btrfs_create_uuid_tree(fs_info); + if (ret) { + btrfs_warn(fs_info, + "failed to create the UUID tree %d", + ret); + goto out; + } + } + +out: + return ret; +} + int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_devices, char *options) { @@ -3218,22 +3265,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device if (ret) goto fail_qgroup; - if (!sb_rdonly(sb)) { - ret = btrfs_cleanup_fs_roots(fs_info); - if (ret) - goto fail_qgroup; - - mutex_lock(&fs_info->cleaner_mutex); - ret = btrfs_recover_relocation(tree_root); - mutex_unlock(&fs_info->cleaner_mutex); - if (ret < 0) { - btrfs_warn(fs_info, "failed to recover relocation: %d", - ret); - err = -EINVAL; - goto fail_qgroup; - } - } - fs_info->fs_root = btrfs_get_fs_root(fs_info, BTRFS_FS_TREE_OBJECTID, true); if (IS_ERR(fs_info->fs_root)) { err = PTR_ERR(fs_info->fs_root); @@ -3286,35 +3317,17 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device } up_read(&fs_info->cleanup_work_sem); - ret = btrfs_resume_balance_async(fs_info); - if (ret) { - btrfs_warn(fs_info, "failed to resume balance: %d", ret); - close_ctree(fs_info); - return ret; - } - - ret = btrfs_resume_dev_replace_async(fs_info); + btrfs_discard_resume(fs_info); + ret = btrfs_mount_rw(fs_info); if (ret) { - btrfs_warn(fs_info, "failed to resume device replace: %d", ret); close_ctree(fs_info); return ret; } - btrfs_qgroup_rescan_resume(fs_info); - btrfs_discard_resume(fs_info); - - if (!fs_info->uuid_root) { - btrfs_info(fs_info, "creating UUID tree"); - ret = btrfs_create_uuid_tree(fs_info); - if (ret) { - btrfs_warn(fs_info, - "failed to create the UUID tree: %d", ret); - close_ctree(fs_info); - return ret; - } - } else if (btrfs_test_opt(fs_info, RESCAN_UUID_TREE) || - fs_info->generation != - btrfs_super_uuid_tree_generation(disk_super)) { + if (fs_info->uuid_root && + (btrfs_test_opt(fs_info, RESCAN_UUID_TREE) || + fs_info->generation != + btrfs_super_uuid_tree_generation(disk_super))) { btrfs_info(fs_info, "checking UUID tree"); ret = btrfs_check_uuid_tree(fs_info); if (ret) { diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h index fee69ced58b4..b3ee9c19be0c 100644 --- a/fs/btrfs/disk-io.h +++ b/fs/btrfs/disk-io.h @@ -50,6 +50,7 @@ struct extent_buffer *btrfs_find_create_tree_block( struct btrfs_fs_info *fs_info, u64 bytenr); void btrfs_clean_tree_block(struct extent_buffer *buf); +int btrfs_mount_rw(struct btrfs_fs_info *fs_info); int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_devices, char *options); diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 8840a4fa81eb..56bfa23bc52f 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1831,7 +1831,6 @@ static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info, static int btrfs_remount(struct super_block *sb, int *flags, char *data) { struct btrfs_fs_info *fs_info = btrfs_sb(sb); - struct btrfs_root *root = fs_info->tree_root; unsigned old_flags = sb->s_flags; unsigned long old_opts = fs_info->mount_opt; unsigned long old_compress_type = fs_info->compress_type; @@ -1924,39 +1923,15 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data) goto restore; } - ret = btrfs_cleanup_fs_roots(fs_info); - if (ret) - goto restore; - - /* recover relocation */ - mutex_lock(&fs_info->cleaner_mutex); - ret = btrfs_recover_relocation(root); - mutex_unlock(&fs_info->cleaner_mutex); - if (ret) - goto restore; - - ret = btrfs_resume_balance_async(fs_info); + /* + * NOTE: when remounting with a change that does writes, don't + * put it anywhere above this point, as we are not sure to be + * safe to write until we pass the above checks. + */ + ret = btrfs_mount_rw(fs_info); if (ret) goto restore; - ret = btrfs_resume_dev_replace_async(fs_info); - if (ret) { - btrfs_warn(fs_info, "failed to resume dev_replace"); - goto restore; - } - - btrfs_qgroup_rescan_resume(fs_info); - - if (!fs_info->uuid_root) { - btrfs_info(fs_info, "creating UUID tree"); - ret = btrfs_create_uuid_tree(fs_info); - if (ret) { - btrfs_warn(fs_info, - "failed to create the UUID tree %d", - ret); - goto restore; - } - } sb->s_flags &= ~SB_RDONLY; set_bit(BTRFS_FS_OPEN, &fs_info->flags);
Mounting rw and remounting from ro to rw naturally share invariants and functionality which result in a correctly setup rw filesystem. Luckily, there is even a strong unity in the code which implements them. In mount's open_ctree, these operations mostly happen after an early return for ro file systems, and in remount, they happen in a section devoted to remounting ro->rw, after some remount specific validation passes. However, there are unfortunately a few differences. There are small deviations in the order of some of the operations, remount does not cleanup orphan inodes in root_tree or fs_tree, remount does not create the free space tree, and remount does not handle "one-shot" mount options like clear_cache and uuid tree rescan. Since we want to add building the free space tree to remount, and since it is possible to leak orphans on a filesystem mounted as ro then remounted rw (common for the root filesystem when booting), we would benefit from unifying the logic between the two codepaths. This patch only lifts the existing common functionality, and leaves a natural path for fixing the discrepancies. Signed-off-by: Boris Burkov <boris@bur.io> --- fs/btrfs/disk-io.c | 93 ++++++++++++++++++++++++++-------------------- fs/btrfs/disk-io.h | 1 + fs/btrfs/super.c | 37 +++--------------- 3 files changed, 60 insertions(+), 71 deletions(-)