| Message ID | 20240808144759.1330237-1-wozizhi@huawei.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
| Series | [V2] xfs: Make the fsmap more precise | expand |
On Thu, Aug 08, 2024 at 10:47:59PM GMT, Zizhi Wo wrote: > In commit 63ef7a35912d ("xfs: fix interval filtering in multi-step fsmap > queries"), Darrick has solved a fsmap bug about incorrect filter condition. > But I still notice two problems in fsmap: What is different between this patch and the V1? Carlos > > [root@fedora ~]# xfs_io -c 'fsmap -vvvv' /mnt > EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL > 0: 253:32 [0..7]: static fs metadata 0 (0..7) 8 > 1: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 > 2: 253:32 [24..39]: inode btree 0 (24..39) 16 > ...... > > Bug 1: > [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt > [root@fedora ~]# > Normally, we should be able to get [3, 7), but we got nothing. > > Bug 2: > [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt > EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL > 0: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 > Normally, we should be able to get [15, 20), but we obtained a whole > segment of extent. > > The first problem is caused by shifting. When the query interval is before > the first extent which can be find in btree, no records can meet the > requirement. And the gap will be obtained in the last query. However, > rec_daddr is calculated based on the start_block recorded in key[1], which > is converted by calling XFS_BB_TO_FSBT. Then if rec_daddr does not exceed > info->next_daddr, which means keys[1].fmr_physical >> (mp)->m_blkbb_log > <= info->next_daddr, no records will be displayed. In the above example, > 3 >> (mp)->m_blkbb_log = 0 and 7 >> (mp)->m_blkbb_log = 0, so the two are > reduced to 0 and the gap is ignored: > > before calculate ----------------> after shifting > 3(st) 7(ed) 0(st/ed) > |---------| | > sector size block size > > Resolve this issue by introducing the "tail_daddr" field in > xfs_getfsmap_info. This records |key[1].fmr_physical + key[1].length| at > the granularity of sector. If the current query is the last, the rec_daddr > is tail_daddr to prevent missing interval problems caused by shifting. We > only need to focus on the last query, because xfs disks are internally > aligned with disk blocksize that are powers of two and minimum 512, so > there is no problem with shifting in previous queries. > > The second problem is that the resulting range is not truncated precisely > according to the boundary. Currently, the query display mechanism for owner > and missing_owner is different. The query of missing_owner (e.g. freespace > in rmapbt/ unknown space in bnobt) is obtained by subtraction (gap), which > can accurately lock the range. In the query of owner which almostly finded > by btree, as long as certain conditions met, the entire interval is > recorded, regardless of the starting address of the key[0] and key[1] > incoming from the user state. Focus on the following scenario: > > a b > |-------| > query > c d > |----------------|-------------|----------------| > missing owner1 owner missing owner2 > > Currently query is directly displayed as [c, d), the correct display should > be [a, b). This problem is solved by calculating max(a, c) and min(b, d) to > identify the head and tail of the range. To be able to determine the bounds > of the low key, "start_daddr" is introduced in xfs_getfsmap_info. Although > in some scenarios, similar results can be achieved without introducing > "start_daddr" and relying solely on info->next_daddr (e.g. in bnobt), it is > ineffective for overlapping scenarios in rmapbt. > > After applying this patch, both of the above issues have been fixed (the > same applies to boundary queries for the log device and realtime device): > 1) > [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt > EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL > 0: 253:32 [3..6]: static fs metadata 0 (3..6) 4 > 2) > [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt > EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL > 0: 253:32 [15..19]: per-AG metadata 0 (15..19) 5 > > Note that due to the current query range being more precise, high.rm_owner > needs to be handled carefully. When it is 0, set it to the maximum value to > prevent missing intervals in rmapbt. > > Signed-off-by: Zizhi Wo <wozizhi@huawei.com> > --- > fs/xfs/xfs_fsmap.c | 42 ++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 40 insertions(+), 2 deletions(-) > > diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c > index 85dbb46452ca..e7bb21497e5c 100644 > --- a/fs/xfs/xfs_fsmap.c > +++ b/fs/xfs/xfs_fsmap.c > @@ -162,6 +162,8 @@ struct xfs_getfsmap_info { > xfs_daddr_t next_daddr; /* next daddr we expect */ > /* daddr of low fsmap key when we're using the rtbitmap */ > xfs_daddr_t low_daddr; > + xfs_daddr_t start_daddr; /* daddr of low fsmap key */ > + xfs_daddr_t end_daddr; /* daddr of high fsmap key */ > u64 missing_owner; /* owner of holes */ > u32 dev; /* device id */ > /* > @@ -276,6 +278,7 @@ xfs_getfsmap_helper( > struct xfs_mount *mp = tp->t_mountp; > bool shared; > int error; > + int trunc_len; > > if (fatal_signal_pending(current)) > return -EINTR; > @@ -283,6 +286,13 @@ xfs_getfsmap_helper( > if (len_daddr == 0) > len_daddr = XFS_FSB_TO_BB(mp, rec->rm_blockcount); > > + /* > + * Determine the maximum boundary of the query to prepare for > + * subsequent truncation. > + */ > + if (info->last && info->end_daddr) > + rec_daddr = info->end_daddr; > + > /* > * Filter out records that start before our startpoint, if the > * caller requested that. > @@ -348,6 +358,21 @@ xfs_getfsmap_helper( > return error; > fmr.fmr_offset = XFS_FSB_TO_BB(mp, rec->rm_offset); > fmr.fmr_length = len_daddr; > + /* If the start address of the record is before the low key, truncate left. */ > + if (info->start_daddr > rec_daddr) { > + trunc_len = info->start_daddr - rec_daddr; > + fmr.fmr_physical += trunc_len; > + fmr.fmr_length -= trunc_len; > + /* need to update the offset in rmapbt. */ > + if (info->missing_owner == XFS_FMR_OWN_FREE) > + fmr.fmr_offset += trunc_len; > + } > + /* If the end address of the record exceeds the high key, truncate right. */ > + if (info->end_daddr) { > + fmr.fmr_length = umin(fmr.fmr_length, info->end_daddr - fmr.fmr_physical); > + if (fmr.fmr_length == 0) > + goto out; > + } > if (rec->rm_flags & XFS_RMAP_UNWRITTEN) > fmr.fmr_flags |= FMR_OF_PREALLOC; > if (rec->rm_flags & XFS_RMAP_ATTR_FORK) > @@ -364,7 +389,7 @@ xfs_getfsmap_helper( > > xfs_getfsmap_format(mp, &fmr, info); > out: > - rec_daddr += len_daddr; > + rec_daddr = fmr.fmr_physical + fmr.fmr_length; > if (info->next_daddr < rec_daddr) > info->next_daddr = rec_daddr; > return 0; > @@ -655,6 +680,13 @@ __xfs_getfsmap_datadev( > error = xfs_fsmap_owner_to_rmap(&info->high, &keys[1]); > if (error) > break; > + /* > + * Set the owner of high_key to the maximum again to > + * prevent missing intervals during the query. > + */ > + if (info->high.rm_owner == 0 && > + info->missing_owner == XFS_FMR_OWN_FREE) > + info->high.rm_owner = ULLONG_MAX; > xfs_getfsmap_set_irec_flags(&info->high, &keys[1]); > } > > @@ -946,6 +978,9 @@ xfs_getfsmap( > > info.next_daddr = head->fmh_keys[0].fmr_physical + > head->fmh_keys[0].fmr_length; > + /* Assignment is performed only for the first time. */ > + if (head->fmh_keys[0].fmr_length == 0) > + info.start_daddr = info.next_daddr; > info.fsmap_recs = fsmap_recs; > info.head = head; > > @@ -966,8 +1001,10 @@ xfs_getfsmap( > * low key, zero out the low key so that we get > * everything from the beginning. > */ > - if (handlers[i].dev == head->fmh_keys[1].fmr_device) > + if (handlers[i].dev == head->fmh_keys[1].fmr_device) { > dkeys[1] = head->fmh_keys[1]; > + info.end_daddr = dkeys[1].fmr_physical + dkeys[1].fmr_length; > + } > if (handlers[i].dev > head->fmh_keys[0].fmr_device) > memset(&dkeys[0], 0, sizeof(struct xfs_fsmap)); > > @@ -991,6 +1028,7 @@ xfs_getfsmap( > xfs_trans_cancel(tp); > tp = NULL; > info.next_daddr = 0; > + info.start_daddr = 0; > } > > if (tp) > -- > 2.39.2 > >
在 2024/8/8 23:29, Carlos Maiolino 写道: > On Thu, Aug 08, 2024 at 10:47:59PM GMT, Zizhi Wo wrote: >> In commit 63ef7a35912d ("xfs: fix interval filtering in multi-step fsmap >> queries"), Darrick has solved a fsmap bug about incorrect filter condition. >> But I still notice two problems in fsmap: > > What is different between this patch and the V1? > > Carlos > I'm sorry, due to my oversight, many recipients were missing in the To field of the V1 version. The content hasn't changed... Thanks, Zizhi Wo >> >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv' /mnt >> EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL >> 0: 253:32 [0..7]: static fs metadata 0 (0..7) 8 >> 1: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 >> 2: 253:32 [24..39]: inode btree 0 (24..39) 16 >> ...... >> >> Bug 1: >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt >> [root@fedora ~]# >> Normally, we should be able to get [3, 7), but we got nothing. >> >> Bug 2: >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt >> EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL >> 0: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 >> Normally, we should be able to get [15, 20), but we obtained a whole >> segment of extent. >> >> The first problem is caused by shifting. When the query interval is before >> the first extent which can be find in btree, no records can meet the >> requirement. And the gap will be obtained in the last query. However, >> rec_daddr is calculated based on the start_block recorded in key[1], which >> is converted by calling XFS_BB_TO_FSBT. Then if rec_daddr does not exceed >> info->next_daddr, which means keys[1].fmr_physical >> (mp)->m_blkbb_log >> <= info->next_daddr, no records will be displayed. In the above example, >> 3 >> (mp)->m_blkbb_log = 0 and 7 >> (mp)->m_blkbb_log = 0, so the two are >> reduced to 0 and the gap is ignored: >> >> before calculate ----------------> after shifting >> 3(st) 7(ed) 0(st/ed) >> |---------| | >> sector size block size >> >> Resolve this issue by introducing the "tail_daddr" field in >> xfs_getfsmap_info. This records |key[1].fmr_physical + key[1].length| at >> the granularity of sector. If the current query is the last, the rec_daddr >> is tail_daddr to prevent missing interval problems caused by shifting. We >> only need to focus on the last query, because xfs disks are internally >> aligned with disk blocksize that are powers of two and minimum 512, so >> there is no problem with shifting in previous queries. >> >> The second problem is that the resulting range is not truncated precisely >> according to the boundary. Currently, the query display mechanism for owner >> and missing_owner is different. The query of missing_owner (e.g. freespace >> in rmapbt/ unknown space in bnobt) is obtained by subtraction (gap), which >> can accurately lock the range. In the query of owner which almostly finded >> by btree, as long as certain conditions met, the entire interval is >> recorded, regardless of the starting address of the key[0] and key[1] >> incoming from the user state. Focus on the following scenario: >> >> a b >> |-------| >> query >> c d >> |----------------|-------------|----------------| >> missing owner1 owner missing owner2 >> >> Currently query is directly displayed as [c, d), the correct display should >> be [a, b). This problem is solved by calculating max(a, c) and min(b, d) to >> identify the head and tail of the range. To be able to determine the bounds >> of the low key, "start_daddr" is introduced in xfs_getfsmap_info. Although >> in some scenarios, similar results can be achieved without introducing >> "start_daddr" and relying solely on info->next_daddr (e.g. in bnobt), it is >> ineffective for overlapping scenarios in rmapbt. >> >> After applying this patch, both of the above issues have been fixed (the >> same applies to boundary queries for the log device and realtime device): >> 1) >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt >> EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL >> 0: 253:32 [3..6]: static fs metadata 0 (3..6) 4 >> 2) >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt >> EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL >> 0: 253:32 [15..19]: per-AG metadata 0 (15..19) 5 >> >> Note that due to the current query range being more precise, high.rm_owner >> needs to be handled carefully. When it is 0, set it to the maximum value to >> prevent missing intervals in rmapbt. >> >> Signed-off-by: Zizhi Wo <wozizhi@huawei.com> >> --- >> fs/xfs/xfs_fsmap.c | 42 ++++++++++++++++++++++++++++++++++++++++-- >> 1 file changed, 40 insertions(+), 2 deletions(-) >> >> diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c >> index 85dbb46452ca..e7bb21497e5c 100644 >> --- a/fs/xfs/xfs_fsmap.c >> +++ b/fs/xfs/xfs_fsmap.c >> @@ -162,6 +162,8 @@ struct xfs_getfsmap_info { >> xfs_daddr_t next_daddr; /* next daddr we expect */ >> /* daddr of low fsmap key when we're using the rtbitmap */ >> xfs_daddr_t low_daddr; >> + xfs_daddr_t start_daddr; /* daddr of low fsmap key */ >> + xfs_daddr_t end_daddr; /* daddr of high fsmap key */ >> u64 missing_owner; /* owner of holes */ >> u32 dev; /* device id */ >> /* >> @@ -276,6 +278,7 @@ xfs_getfsmap_helper( >> struct xfs_mount *mp = tp->t_mountp; >> bool shared; >> int error; >> + int trunc_len; >> >> if (fatal_signal_pending(current)) >> return -EINTR; >> @@ -283,6 +286,13 @@ xfs_getfsmap_helper( >> if (len_daddr == 0) >> len_daddr = XFS_FSB_TO_BB(mp, rec->rm_blockcount); >> >> + /* >> + * Determine the maximum boundary of the query to prepare for >> + * subsequent truncation. >> + */ >> + if (info->last && info->end_daddr) >> + rec_daddr = info->end_daddr; >> + >> /* >> * Filter out records that start before our startpoint, if the >> * caller requested that. >> @@ -348,6 +358,21 @@ xfs_getfsmap_helper( >> return error; >> fmr.fmr_offset = XFS_FSB_TO_BB(mp, rec->rm_offset); >> fmr.fmr_length = len_daddr; >> + /* If the start address of the record is before the low key, truncate left. */ >> + if (info->start_daddr > rec_daddr) { >> + trunc_len = info->start_daddr - rec_daddr; >> + fmr.fmr_physical += trunc_len; >> + fmr.fmr_length -= trunc_len; >> + /* need to update the offset in rmapbt. */ >> + if (info->missing_owner == XFS_FMR_OWN_FREE) >> + fmr.fmr_offset += trunc_len; >> + } >> + /* If the end address of the record exceeds the high key, truncate right. */ >> + if (info->end_daddr) { >> + fmr.fmr_length = umin(fmr.fmr_length, info->end_daddr - fmr.fmr_physical); >> + if (fmr.fmr_length == 0) >> + goto out; >> + } >> if (rec->rm_flags & XFS_RMAP_UNWRITTEN) >> fmr.fmr_flags |= FMR_OF_PREALLOC; >> if (rec->rm_flags & XFS_RMAP_ATTR_FORK) >> @@ -364,7 +389,7 @@ xfs_getfsmap_helper( >> >> xfs_getfsmap_format(mp, &fmr, info); >> out: >> - rec_daddr += len_daddr; >> + rec_daddr = fmr.fmr_physical + fmr.fmr_length; >> if (info->next_daddr < rec_daddr) >> info->next_daddr = rec_daddr; >> return 0; >> @@ -655,6 +680,13 @@ __xfs_getfsmap_datadev( >> error = xfs_fsmap_owner_to_rmap(&info->high, &keys[1]); >> if (error) >> break; >> + /* >> + * Set the owner of high_key to the maximum again to >> + * prevent missing intervals during the query. >> + */ >> + if (info->high.rm_owner == 0 && >> + info->missing_owner == XFS_FMR_OWN_FREE) >> + info->high.rm_owner = ULLONG_MAX; >> xfs_getfsmap_set_irec_flags(&info->high, &keys[1]); >> } >> >> @@ -946,6 +978,9 @@ xfs_getfsmap( >> >> info.next_daddr = head->fmh_keys[0].fmr_physical + >> head->fmh_keys[0].fmr_length; >> + /* Assignment is performed only for the first time. */ >> + if (head->fmh_keys[0].fmr_length == 0) >> + info.start_daddr = info.next_daddr; >> info.fsmap_recs = fsmap_recs; >> info.head = head; >> >> @@ -966,8 +1001,10 @@ xfs_getfsmap( >> * low key, zero out the low key so that we get >> * everything from the beginning. >> */ >> - if (handlers[i].dev == head->fmh_keys[1].fmr_device) >> + if (handlers[i].dev == head->fmh_keys[1].fmr_device) { >> dkeys[1] = head->fmh_keys[1]; >> + info.end_daddr = dkeys[1].fmr_physical + dkeys[1].fmr_length; >> + } >> if (handlers[i].dev > head->fmh_keys[0].fmr_device) >> memset(&dkeys[0], 0, sizeof(struct xfs_fsmap)); >> >> @@ -991,6 +1028,7 @@ xfs_getfsmap( >> xfs_trans_cancel(tp); >> tp = NULL; >> info.next_daddr = 0; >> + info.start_daddr = 0; >> } >> >> if (tp) >> -- >> 2.39.2 >> >>
On Thu, Aug 08, 2024 at 10:47:59PM GMT, Zizhi Wo wrote: > In commit 63ef7a35912d ("xfs: fix interval filtering in multi-step fsmap > queries"), Darrick has solved a fsmap bug about incorrect filter condition. > But I still notice two problems in fsmap: > > [root@fedora ~]# xfs_io -c 'fsmap -vvvv' /mnt > EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL > 0: 253:32 [0..7]: static fs metadata 0 (0..7) 8 > 1: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 > 2: 253:32 [24..39]: inode btree 0 (24..39) 16 > ...... > > Bug 1: > [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt > [root@fedora ~]# > Normally, we should be able to get [3, 7), but we got nothing. > > Bug 2: > [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt > EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL > 0: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 > Normally, we should be able to get [15, 20), but we obtained a whole > segment of extent. > > The first problem is caused by shifting. When the query interval is before > the first extent which can be find in btree, no records can meet the > requirement. And the gap will be obtained in the last query. However, > rec_daddr is calculated based on the start_block recorded in key[1], which > is converted by calling XFS_BB_TO_FSBT. Then if rec_daddr does not exceed > info->next_daddr, which means keys[1].fmr_physical >> (mp)->m_blkbb_log > <= info->next_daddr, no records will be displayed. In the above example, > 3 >> (mp)->m_blkbb_log = 0 and 7 >> (mp)->m_blkbb_log = 0, so the two are > reduced to 0 and the gap is ignored: > > before calculate ----------------> after shifting > 3(st) 7(ed) 0(st/ed) > |---------| | > sector size block size > > Resolve this issue by introducing the "tail_daddr" field in > xfs_getfsmap_info. This records |key[1].fmr_physical + key[1].length| at > the granularity of sector. If the current query is the last, the rec_daddr > is tail_daddr to prevent missing interval problems caused by shifting. You mention the introduction of the 'tail_daddr' field, but your patch does not introduce such field. Your patch description should properly match your patch. > We > only need to focus on the last query, because xfs disks are internally > aligned with disk blocksize that are powers of two and minimum 512, so > there is no problem with shifting in previous queries. > > The second problem is that the resulting range is not truncated precisely > according to the boundary. Even though they are related, I'd prefer these two fixes split this into 2 separated patches, not a single one. This makes reviewers lives easier to follow what you are fixing. > Currently, the query display mechanism for owner > and missing_owner is different. The query of missing_owner (e.g. freespace > in rmapbt/ unknown space in bnobt) is obtained by subtraction (gap), which > can accurately lock the range. In the query of owner which almostly finded > by btree, as long as certain conditions met, the entire interval is > recorded, regardless of the starting address of the key[0] and key[1] > incoming from the user state. Focus on the following scenario: > > a b > |-------| > query > c d > |----------------|-------------|----------------| > missing owner1 owner missing owner2 > > Currently query is directly displayed as [c, d), the correct display should > be [a, b). This problem is solved by calculating max(a, c) and min(b, d) to > identify the head and tail of the range. To be able to determine the bounds > of the low key, "start_daddr" is introduced in xfs_getfsmap_info. Here you properly describe what your patch is doing. Carlos > Although > in some scenarios, similar results can be achieved without introducing > "start_daddr" and relying solely on info->next_daddr (e.g. in bnobt), it is > ineffective for overlapping scenarios in rmapbt. > > After applying this patch, both of the above issues have been fixed (the > same applies to boundary queries for the log device and realtime device): > 1) > [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt > EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL > 0: 253:32 [3..6]: static fs metadata 0 (3..6) 4 > 2) > [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt > EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL > 0: 253:32 [15..19]: per-AG metadata 0 (15..19) 5 > > Note that due to the current query range being more precise, high.rm_owner > needs to be handled carefully. When it is 0, set it to the maximum value to > prevent missing intervals in rmapbt. > > Signed-off-by: Zizhi Wo <wozizhi@huawei.com> > --- > fs/xfs/xfs_fsmap.c | 42 ++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 40 insertions(+), 2 deletions(-) > > diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c > index 85dbb46452ca..e7bb21497e5c 100644 > --- a/fs/xfs/xfs_fsmap.c > +++ b/fs/xfs/xfs_fsmap.c > @@ -162,6 +162,8 @@ struct xfs_getfsmap_info { > xfs_daddr_t next_daddr; /* next daddr we expect */ > /* daddr of low fsmap key when we're using the rtbitmap */ > xfs_daddr_t low_daddr; > + xfs_daddr_t start_daddr; /* daddr of low fsmap key */ > + xfs_daddr_t end_daddr; /* daddr of high fsmap key */ > u64 missing_owner; /* owner of holes */ > u32 dev; /* device id */ > /* > @@ -276,6 +278,7 @@ xfs_getfsmap_helper( > struct xfs_mount *mp = tp->t_mountp; > bool shared; > int error; > + int trunc_len; > > if (fatal_signal_pending(current)) > return -EINTR; > @@ -283,6 +286,13 @@ xfs_getfsmap_helper( > if (len_daddr == 0) > len_daddr = XFS_FSB_TO_BB(mp, rec->rm_blockcount); > > + /* > + * Determine the maximum boundary of the query to prepare for > + * subsequent truncation. > + */ > + if (info->last && info->end_daddr) > + rec_daddr = info->end_daddr; > + > /* > * Filter out records that start before our startpoint, if the > * caller requested that. > @@ -348,6 +358,21 @@ xfs_getfsmap_helper( > return error; > fmr.fmr_offset = XFS_FSB_TO_BB(mp, rec->rm_offset); > fmr.fmr_length = len_daddr; > + /* If the start address of the record is before the low key, truncate left. */ > + if (info->start_daddr > rec_daddr) { > + trunc_len = info->start_daddr - rec_daddr; > + fmr.fmr_physical += trunc_len; > + fmr.fmr_length -= trunc_len; > + /* need to update the offset in rmapbt. */ > + if (info->missing_owner == XFS_FMR_OWN_FREE) > + fmr.fmr_offset += trunc_len; > + } > + /* If the end address of the record exceeds the high key, truncate right. */ > + if (info->end_daddr) { > + fmr.fmr_length = umin(fmr.fmr_length, info->end_daddr - fmr.fmr_physical); > + if (fmr.fmr_length == 0) > + goto out; > + } > if (rec->rm_flags & XFS_RMAP_UNWRITTEN) > fmr.fmr_flags |= FMR_OF_PREALLOC; > if (rec->rm_flags & XFS_RMAP_ATTR_FORK) > @@ -364,7 +389,7 @@ xfs_getfsmap_helper( > > xfs_getfsmap_format(mp, &fmr, info); > out: > - rec_daddr += len_daddr; > + rec_daddr = fmr.fmr_physical + fmr.fmr_length; > if (info->next_daddr < rec_daddr) > info->next_daddr = rec_daddr; > return 0; > @@ -655,6 +680,13 @@ __xfs_getfsmap_datadev( > error = xfs_fsmap_owner_to_rmap(&info->high, &keys[1]); > if (error) > break; > + /* > + * Set the owner of high_key to the maximum again to > + * prevent missing intervals during the query. > + */ > + if (info->high.rm_owner == 0 && > + info->missing_owner == XFS_FMR_OWN_FREE) > + info->high.rm_owner = ULLONG_MAX; > xfs_getfsmap_set_irec_flags(&info->high, &keys[1]); > } > > @@ -946,6 +978,9 @@ xfs_getfsmap( > > info.next_daddr = head->fmh_keys[0].fmr_physical + > head->fmh_keys[0].fmr_length; > + /* Assignment is performed only for the first time. */ > + if (head->fmh_keys[0].fmr_length == 0) > + info.start_daddr = info.next_daddr; > info.fsmap_recs = fsmap_recs; > info.head = head; > > @@ -966,8 +1001,10 @@ xfs_getfsmap( > * low key, zero out the low key so that we get > * everything from the beginning. > */ > - if (handlers[i].dev == head->fmh_keys[1].fmr_device) > + if (handlers[i].dev == head->fmh_keys[1].fmr_device) { > dkeys[1] = head->fmh_keys[1]; > + info.end_daddr = dkeys[1].fmr_physical + dkeys[1].fmr_length; > + } > if (handlers[i].dev > head->fmh_keys[0].fmr_device) > memset(&dkeys[0], 0, sizeof(struct xfs_fsmap)); > > @@ -991,6 +1028,7 @@ xfs_getfsmap( > xfs_trans_cancel(tp); > tp = NULL; > info.next_daddr = 0; > + info.start_daddr = 0; > } > > if (tp) > -- > 2.39.2 > >
On Thu, Aug 08, 2024 at 10:47:59PM +0800, Zizhi Wo wrote: > In commit 63ef7a35912d ("xfs: fix interval filtering in multi-step fsmap > queries"), Darrick has solved a fsmap bug about incorrect filter condition. > But I still notice two problems in fsmap: > > [root@fedora ~]# xfs_io -c 'fsmap -vvvv' /mnt > EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL > 0: 253:32 [0..7]: static fs metadata 0 (0..7) 8 > 1: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 > 2: 253:32 [24..39]: inode btree 0 (24..39) 16 > ...... > > Bug 1: > [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt > [root@fedora ~]# > Normally, we should be able to get [3, 7), but we got nothing. Hmm, yes, that's a bug. > Bug 2: > [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt > EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL > 0: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 > Normally, we should be able to get [15, 20), but we obtained a whole > segment of extent. Both filesystems implementing GETFSMAP (ext4 and xfs) can return larger mapping than what was requested. Userspace can decide to trim the mappings before using them, which is why the kernel doesn't do that on its own. > The first problem is caused by shifting. When the query interval is before > the first extent which can be find in btree, no records can meet the > requirement. And the gap will be obtained in the last query. However, > rec_daddr is calculated based on the start_block recorded in key[1], which > is converted by calling XFS_BB_TO_FSBT. Then if rec_daddr does not exceed > info->next_daddr, which means keys[1].fmr_physical >> (mp)->m_blkbb_log > <= info->next_daddr, no records will be displayed. In the above example, > 3 >> (mp)->m_blkbb_log = 0 and 7 >> (mp)->m_blkbb_log = 0, so the two are > reduced to 0 and the gap is ignored: > > before calculate ----------------> after shifting > 3(st) 7(ed) 0(st/ed) > |---------| | > sector size block size > > Resolve this issue by introducing the "tail_daddr" field in > xfs_getfsmap_info. This records |key[1].fmr_physical + key[1].length| at > the granularity of sector. If the current query is the last, the rec_daddr > is tail_daddr to prevent missing interval problems caused by shifting. We > only need to focus on the last query, because xfs disks are internally > aligned with disk blocksize that are powers of two and minimum 512, so > there is no problem with shifting in previous queries. Not sure what "tail_daddr" is; the patch adds {start,end}_daddr. I agree that fsmap -vvvv -d 3 7 ought to return "static fs metadata" instead of nothing, however. Can you send a separate fix for "Bug 1", please? --D > The second problem is that the resulting range is not truncated precisely > according to the boundary. Currently, the query display mechanism for owner > and missing_owner is different. The query of missing_owner (e.g. freespace > in rmapbt/ unknown space in bnobt) is obtained by subtraction (gap), which > can accurately lock the range. In the query of owner which almostly finded > by btree, as long as certain conditions met, the entire interval is > recorded, regardless of the starting address of the key[0] and key[1] > incoming from the user state. Focus on the following scenario: > > a b > |-------| > query > c d > |----------------|-------------|----------------| > missing owner1 owner missing owner2 > > Currently query is directly displayed as [c, d), the correct display should > be [a, b). This problem is solved by calculating max(a, c) and min(b, d) to > identify the head and tail of the range. To be able to determine the bounds > of the low key, "start_daddr" is introduced in xfs_getfsmap_info. Although > in some scenarios, similar results can be achieved without introducing > "start_daddr" and relying solely on info->next_daddr (e.g. in bnobt), it is > ineffective for overlapping scenarios in rmapbt. > > After applying this patch, both of the above issues have been fixed (the > same applies to boundary queries for the log device and realtime device): > 1) > [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt > EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL > 0: 253:32 [3..6]: static fs metadata 0 (3..6) 4 > 2) > [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt > EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL > 0: 253:32 [15..19]: per-AG metadata 0 (15..19) 5 > > Note that due to the current query range being more precise, high.rm_owner > needs to be handled carefully. When it is 0, set it to the maximum value to > prevent missing intervals in rmapbt. > > Signed-off-by: Zizhi Wo <wozizhi@huawei.com> > --- > fs/xfs/xfs_fsmap.c | 42 ++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 40 insertions(+), 2 deletions(-) > > diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c > index 85dbb46452ca..e7bb21497e5c 100644 > --- a/fs/xfs/xfs_fsmap.c > +++ b/fs/xfs/xfs_fsmap.c > @@ -162,6 +162,8 @@ struct xfs_getfsmap_info { > xfs_daddr_t next_daddr; /* next daddr we expect */ > /* daddr of low fsmap key when we're using the rtbitmap */ > xfs_daddr_t low_daddr; > + xfs_daddr_t start_daddr; /* daddr of low fsmap key */ > + xfs_daddr_t end_daddr; /* daddr of high fsmap key */ > u64 missing_owner; /* owner of holes */ > u32 dev; /* device id */ > /* > @@ -276,6 +278,7 @@ xfs_getfsmap_helper( > struct xfs_mount *mp = tp->t_mountp; > bool shared; > int error; > + int trunc_len; > > if (fatal_signal_pending(current)) > return -EINTR; > @@ -283,6 +286,13 @@ xfs_getfsmap_helper( > if (len_daddr == 0) > len_daddr = XFS_FSB_TO_BB(mp, rec->rm_blockcount); > > + /* > + * Determine the maximum boundary of the query to prepare for > + * subsequent truncation. > + */ > + if (info->last && info->end_daddr) > + rec_daddr = info->end_daddr; > + > /* > * Filter out records that start before our startpoint, if the > * caller requested that. > @@ -348,6 +358,21 @@ xfs_getfsmap_helper( > return error; > fmr.fmr_offset = XFS_FSB_TO_BB(mp, rec->rm_offset); > fmr.fmr_length = len_daddr; > + /* If the start address of the record is before the low key, truncate left. */ > + if (info->start_daddr > rec_daddr) { > + trunc_len = info->start_daddr - rec_daddr; > + fmr.fmr_physical += trunc_len; > + fmr.fmr_length -= trunc_len; > + /* need to update the offset in rmapbt. */ > + if (info->missing_owner == XFS_FMR_OWN_FREE) > + fmr.fmr_offset += trunc_len; > + } > + /* If the end address of the record exceeds the high key, truncate right. */ > + if (info->end_daddr) { > + fmr.fmr_length = umin(fmr.fmr_length, info->end_daddr - fmr.fmr_physical); > + if (fmr.fmr_length == 0) > + goto out; > + } > if (rec->rm_flags & XFS_RMAP_UNWRITTEN) > fmr.fmr_flags |= FMR_OF_PREALLOC; > if (rec->rm_flags & XFS_RMAP_ATTR_FORK) > @@ -364,7 +389,7 @@ xfs_getfsmap_helper( > > xfs_getfsmap_format(mp, &fmr, info); > out: > - rec_daddr += len_daddr; > + rec_daddr = fmr.fmr_physical + fmr.fmr_length; > if (info->next_daddr < rec_daddr) > info->next_daddr = rec_daddr; > return 0; > @@ -655,6 +680,13 @@ __xfs_getfsmap_datadev( > error = xfs_fsmap_owner_to_rmap(&info->high, &keys[1]); > if (error) > break; > + /* > + * Set the owner of high_key to the maximum again to > + * prevent missing intervals during the query. > + */ > + if (info->high.rm_owner == 0 && > + info->missing_owner == XFS_FMR_OWN_FREE) > + info->high.rm_owner = ULLONG_MAX; > xfs_getfsmap_set_irec_flags(&info->high, &keys[1]); > } > > @@ -946,6 +978,9 @@ xfs_getfsmap( > > info.next_daddr = head->fmh_keys[0].fmr_physical + > head->fmh_keys[0].fmr_length; > + /* Assignment is performed only for the first time. */ > + if (head->fmh_keys[0].fmr_length == 0) > + info.start_daddr = info.next_daddr; > info.fsmap_recs = fsmap_recs; > info.head = head; > > @@ -966,8 +1001,10 @@ xfs_getfsmap( > * low key, zero out the low key so that we get > * everything from the beginning. > */ > - if (handlers[i].dev == head->fmh_keys[1].fmr_device) > + if (handlers[i].dev == head->fmh_keys[1].fmr_device) { > dkeys[1] = head->fmh_keys[1]; > + info.end_daddr = dkeys[1].fmr_physical + dkeys[1].fmr_length; > + } > if (handlers[i].dev > head->fmh_keys[0].fmr_device) > memset(&dkeys[0], 0, sizeof(struct xfs_fsmap)); > > @@ -991,6 +1028,7 @@ xfs_getfsmap( > xfs_trans_cancel(tp); > tp = NULL; > info.next_daddr = 0; > + info.start_daddr = 0; > } > > if (tp) > -- > 2.39.2 > >
在 2024/8/10 0:22, Darrick J. Wong 写道: > On Thu, Aug 08, 2024 at 10:47:59PM +0800, Zizhi Wo wrote: >> In commit 63ef7a35912d ("xfs: fix interval filtering in multi-step fsmap >> queries"), Darrick has solved a fsmap bug about incorrect filter condition. >> But I still notice two problems in fsmap: >> >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv' /mnt >> EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL >> 0: 253:32 [0..7]: static fs metadata 0 (0..7) 8 >> 1: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 >> 2: 253:32 [24..39]: inode btree 0 (24..39) 16 >> ...... >> >> Bug 1: >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt >> [root@fedora ~]# >> Normally, we should be able to get [3, 7), but we got nothing. > > Hmm, yes, that's a bug. > >> Bug 2: >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt >> EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL >> 0: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 >> Normally, we should be able to get [15, 20), but we obtained a whole >> segment of extent. > > Both filesystems implementing GETFSMAP (ext4 and xfs) can return larger > mapping than what was requested. Userspace can decide to trim the > mappings before using them, which is why the kernel doesn't do that on > its own. > Oh, I see. I noticed that querying the missing_owner range could be precise, but querying the non-missing_owner range only displayed the whole thing. I found this inconsistent, so I fixed the issue myself... >> The first problem is caused by shifting. When the query interval is before >> the first extent which can be find in btree, no records can meet the >> requirement. And the gap will be obtained in the last query. However, >> rec_daddr is calculated based on the start_block recorded in key[1], which >> is converted by calling XFS_BB_TO_FSBT. Then if rec_daddr does not exceed >> info->next_daddr, which means keys[1].fmr_physical >> (mp)->m_blkbb_log >> <= info->next_daddr, no records will be displayed. In the above example, >> 3 >> (mp)->m_blkbb_log = 0 and 7 >> (mp)->m_blkbb_log = 0, so the two are >> reduced to 0 and the gap is ignored: >> >> before calculate ----------------> after shifting >> 3(st) 7(ed) 0(st/ed) >> |---------| | >> sector size block size >> >> Resolve this issue by introducing the "tail_daddr" field in >> xfs_getfsmap_info. This records |key[1].fmr_physical + key[1].length| at >> the granularity of sector. If the current query is the last, the rec_daddr >> is tail_daddr to prevent missing interval problems caused by shifting. We >> only need to focus on the last query, because xfs disks are internally >> aligned with disk blocksize that are powers of two and minimum 512, so >> there is no problem with shifting in previous queries. > > Not sure what "tail_daddr" is; the patch adds {start,end}_daddr. I > agree that fsmap -vvvv -d 3 7 ought to return "static fs metadata" > instead of nothing, however. > > Can you send a separate fix for "Bug 1", please? > > --D I'm very sorry, I mistakenly referred to "end_daddr" as "tail_daddr"! "end_daddr" is mainly used to fix the first bug, where the last range wasn't calculated with sector granularity, causing query issues. The second bug fix relies on both "start_daddr" and "end_daddr". But as discussed above, the second one isn't really an issue? So I'll only fix the first bug in the next patch version. Thanks, Zizhi Wo > >> The second problem is that the resulting range is not truncated precisely >> according to the boundary. Currently, the query display mechanism for owner >> and missing_owner is different. The query of missing_owner (e.g. freespace >> in rmapbt/ unknown space in bnobt) is obtained by subtraction (gap), which >> can accurately lock the range. In the query of owner which almostly finded >> by btree, as long as certain conditions met, the entire interval is >> recorded, regardless of the starting address of the key[0] and key[1] >> incoming from the user state. Focus on the following scenario: >> >> a b >> |-------| >> query >> c d >> |----------------|-------------|----------------| >> missing owner1 owner missing owner2 >> >> Currently query is directly displayed as [c, d), the correct display should >> be [a, b). This problem is solved by calculating max(a, c) and min(b, d) to >> identify the head and tail of the range. To be able to determine the bounds >> of the low key, "start_daddr" is introduced in xfs_getfsmap_info. Although >> in some scenarios, similar results can be achieved without introducing >> "start_daddr" and relying solely on info->next_daddr (e.g. in bnobt), it is >> ineffective for overlapping scenarios in rmapbt. >> >> After applying this patch, both of the above issues have been fixed (the >> same applies to boundary queries for the log device and realtime device): >> 1) >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt >> EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL >> 0: 253:32 [3..6]: static fs metadata 0 (3..6) 4 >> 2) >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt >> EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL >> 0: 253:32 [15..19]: per-AG metadata 0 (15..19) 5 >> >> Note that due to the current query range being more precise, high.rm_owner >> needs to be handled carefully. When it is 0, set it to the maximum value to >> prevent missing intervals in rmapbt. >> >> Signed-off-by: Zizhi Wo <wozizhi@huawei.com> >> --- >> fs/xfs/xfs_fsmap.c | 42 ++++++++++++++++++++++++++++++++++++++++-- >> 1 file changed, 40 insertions(+), 2 deletions(-) >> >> diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c >> index 85dbb46452ca..e7bb21497e5c 100644 >> --- a/fs/xfs/xfs_fsmap.c >> +++ b/fs/xfs/xfs_fsmap.c >> @@ -162,6 +162,8 @@ struct xfs_getfsmap_info { >> xfs_daddr_t next_daddr; /* next daddr we expect */ >> /* daddr of low fsmap key when we're using the rtbitmap */ >> xfs_daddr_t low_daddr; >> + xfs_daddr_t start_daddr; /* daddr of low fsmap key */ >> + xfs_daddr_t end_daddr; /* daddr of high fsmap key */ >> u64 missing_owner; /* owner of holes */ >> u32 dev; /* device id */ >> /* >> @@ -276,6 +278,7 @@ xfs_getfsmap_helper( >> struct xfs_mount *mp = tp->t_mountp; >> bool shared; >> int error; >> + int trunc_len; >> >> if (fatal_signal_pending(current)) >> return -EINTR; >> @@ -283,6 +286,13 @@ xfs_getfsmap_helper( >> if (len_daddr == 0) >> len_daddr = XFS_FSB_TO_BB(mp, rec->rm_blockcount); >> >> + /* >> + * Determine the maximum boundary of the query to prepare for >> + * subsequent truncation. >> + */ >> + if (info->last && info->end_daddr) >> + rec_daddr = info->end_daddr; >> + >> /* >> * Filter out records that start before our startpoint, if the >> * caller requested that. >> @@ -348,6 +358,21 @@ xfs_getfsmap_helper( >> return error; >> fmr.fmr_offset = XFS_FSB_TO_BB(mp, rec->rm_offset); >> fmr.fmr_length = len_daddr; >> + /* If the start address of the record is before the low key, truncate left. */ >> + if (info->start_daddr > rec_daddr) { >> + trunc_len = info->start_daddr - rec_daddr; >> + fmr.fmr_physical += trunc_len; >> + fmr.fmr_length -= trunc_len; >> + /* need to update the offset in rmapbt. */ >> + if (info->missing_owner == XFS_FMR_OWN_FREE) >> + fmr.fmr_offset += trunc_len; >> + } >> + /* If the end address of the record exceeds the high key, truncate right. */ >> + if (info->end_daddr) { >> + fmr.fmr_length = umin(fmr.fmr_length, info->end_daddr - fmr.fmr_physical); >> + if (fmr.fmr_length == 0) >> + goto out; >> + } >> if (rec->rm_flags & XFS_RMAP_UNWRITTEN) >> fmr.fmr_flags |= FMR_OF_PREALLOC; >> if (rec->rm_flags & XFS_RMAP_ATTR_FORK) >> @@ -364,7 +389,7 @@ xfs_getfsmap_helper( >> >> xfs_getfsmap_format(mp, &fmr, info); >> out: >> - rec_daddr += len_daddr; >> + rec_daddr = fmr.fmr_physical + fmr.fmr_length; >> if (info->next_daddr < rec_daddr) >> info->next_daddr = rec_daddr; >> return 0; >> @@ -655,6 +680,13 @@ __xfs_getfsmap_datadev( >> error = xfs_fsmap_owner_to_rmap(&info->high, &keys[1]); >> if (error) >> break; >> + /* >> + * Set the owner of high_key to the maximum again to >> + * prevent missing intervals during the query. >> + */ >> + if (info->high.rm_owner == 0 && >> + info->missing_owner == XFS_FMR_OWN_FREE) >> + info->high.rm_owner = ULLONG_MAX; >> xfs_getfsmap_set_irec_flags(&info->high, &keys[1]); >> } >> >> @@ -946,6 +978,9 @@ xfs_getfsmap( >> >> info.next_daddr = head->fmh_keys[0].fmr_physical + >> head->fmh_keys[0].fmr_length; >> + /* Assignment is performed only for the first time. */ >> + if (head->fmh_keys[0].fmr_length == 0) >> + info.start_daddr = info.next_daddr; >> info.fsmap_recs = fsmap_recs; >> info.head = head; >> >> @@ -966,8 +1001,10 @@ xfs_getfsmap( >> * low key, zero out the low key so that we get >> * everything from the beginning. >> */ >> - if (handlers[i].dev == head->fmh_keys[1].fmr_device) >> + if (handlers[i].dev == head->fmh_keys[1].fmr_device) { >> dkeys[1] = head->fmh_keys[1]; >> + info.end_daddr = dkeys[1].fmr_physical + dkeys[1].fmr_length; >> + } >> if (handlers[i].dev > head->fmh_keys[0].fmr_device) >> memset(&dkeys[0], 0, sizeof(struct xfs_fsmap)); >> >> @@ -991,6 +1028,7 @@ xfs_getfsmap( >> xfs_trans_cancel(tp); >> tp = NULL; >> info.next_daddr = 0; >> + info.start_daddr = 0; >> } >> >> if (tp) >> -- >> 2.39.2 >> >>
在 2024/8/9 17:09, Carlos Maiolino 写道: > On Thu, Aug 08, 2024 at 10:47:59PM GMT, Zizhi Wo wrote: >> In commit 63ef7a35912d ("xfs: fix interval filtering in multi-step fsmap >> queries"), Darrick has solved a fsmap bug about incorrect filter condition. >> But I still notice two problems in fsmap: >> >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv' /mnt >> EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL >> 0: 253:32 [0..7]: static fs metadata 0 (0..7) 8 >> 1: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 >> 2: 253:32 [24..39]: inode btree 0 (24..39) 16 >> ...... >> >> Bug 1: >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt >> [root@fedora ~]# >> Normally, we should be able to get [3, 7), but we got nothing. >> >> Bug 2: >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt >> EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL >> 0: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 >> Normally, we should be able to get [15, 20), but we obtained a whole >> segment of extent. >> >> The first problem is caused by shifting. When the query interval is before >> the first extent which can be find in btree, no records can meet the >> requirement. And the gap will be obtained in the last query. However, >> rec_daddr is calculated based on the start_block recorded in key[1], which >> is converted by calling XFS_BB_TO_FSBT. Then if rec_daddr does not exceed >> info->next_daddr, which means keys[1].fmr_physical >> (mp)->m_blkbb_log >> <= info->next_daddr, no records will be displayed. In the above example, >> 3 >> (mp)->m_blkbb_log = 0 and 7 >> (mp)->m_blkbb_log = 0, so the two are >> reduced to 0 and the gap is ignored: >> >> before calculate ----------------> after shifting >> 3(st) 7(ed) 0(st/ed) >> |---------| | >> sector size block size >> >> Resolve this issue by introducing the "tail_daddr" field in >> xfs_getfsmap_info. This records |key[1].fmr_physical + key[1].length| at >> the granularity of sector. If the current query is the last, the rec_daddr >> is tail_daddr to prevent missing interval problems caused by shifting. > > You mention the introduction of the 'tail_daddr' field, but your patch > does not introduce such field. Your patch description should properly match > your patch. > I'm very sorry, I mistakenly referred to "end_daddr" as "tail_daddr"! Next time, I will carefully review the commit message of the patch. To fix the first bug, introducing "end_daddr" is sufficient, but fixing the second bug requires both "start_daddr" and "end_daddr". > >> We >> only need to focus on the last query, because xfs disks are internally >> aligned with disk blocksize that are powers of two and minimum 512, so >> there is no problem with shifting in previous queries. >> >> The second problem is that the resulting range is not truncated precisely >> according to the boundary. > > Even though they are related, I'd prefer these two fixes split this into 2 > separated patches, not a single one. This makes reviewers lives easier to > follow what you are fixing. > Sure, I'll split them. Thanks for the suggestion. However, as Darrick mentioned, the second issue of displaying the entire range might not be a problem. So I'll address the first bug in the next version. Thanks, Zizhi Wo > >> Currently, the query display mechanism for owner >> and missing_owner is different. The query of missing_owner (e.g. freespace >> in rmapbt/ unknown space in bnobt) is obtained by subtraction (gap), which >> can accurately lock the range. In the query of owner which almostly finded >> by btree, as long as certain conditions met, the entire interval is >> recorded, regardless of the starting address of the key[0] and key[1] >> incoming from the user state. Focus on the following scenario: >> >> a b >> |-------| >> query >> c d >> |----------------|-------------|----------------| >> missing owner1 owner missing owner2 >> >> Currently query is directly displayed as [c, d), the correct display should >> be [a, b). This problem is solved by calculating max(a, c) and min(b, d) to >> identify the head and tail of the range. To be able to determine the bounds >> of the low key, "start_daddr" is introduced in xfs_getfsmap_info. > > Here you properly describe what your patch is doing. > > Carlos > >> Although >> in some scenarios, similar results can be achieved without introducing >> "start_daddr" and relying solely on info->next_daddr (e.g. in bnobt), it is >> ineffective for overlapping scenarios in rmapbt. >> >> After applying this patch, both of the above issues have been fixed (the >> same applies to boundary queries for the log device and realtime device): >> 1) >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt >> EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL >> 0: 253:32 [3..6]: static fs metadata 0 (3..6) 4 >> 2) >> [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt >> EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL >> 0: 253:32 [15..19]: per-AG metadata 0 (15..19) 5 >> >> Note that due to the current query range being more precise, high.rm_owner >> needs to be handled carefully. When it is 0, set it to the maximum value to >> prevent missing intervals in rmapbt. >> >> Signed-off-by: Zizhi Wo <wozizhi@huawei.com> >> --- >> fs/xfs/xfs_fsmap.c | 42 ++++++++++++++++++++++++++++++++++++++++-- >> 1 file changed, 40 insertions(+), 2 deletions(-) >> >> diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c >> index 85dbb46452ca..e7bb21497e5c 100644 >> --- a/fs/xfs/xfs_fsmap.c >> +++ b/fs/xfs/xfs_fsmap.c >> @@ -162,6 +162,8 @@ struct xfs_getfsmap_info { >> xfs_daddr_t next_daddr; /* next daddr we expect */ >> /* daddr of low fsmap key when we're using the rtbitmap */ >> xfs_daddr_t low_daddr; >> + xfs_daddr_t start_daddr; /* daddr of low fsmap key */ >> + xfs_daddr_t end_daddr; /* daddr of high fsmap key */ >> u64 missing_owner; /* owner of holes */ >> u32 dev; /* device id */ >> /* >> @@ -276,6 +278,7 @@ xfs_getfsmap_helper( >> struct xfs_mount *mp = tp->t_mountp; >> bool shared; >> int error; >> + int trunc_len; >> >> if (fatal_signal_pending(current)) >> return -EINTR; >> @@ -283,6 +286,13 @@ xfs_getfsmap_helper( >> if (len_daddr == 0) >> len_daddr = XFS_FSB_TO_BB(mp, rec->rm_blockcount); >> >> + /* >> + * Determine the maximum boundary of the query to prepare for >> + * subsequent truncation. >> + */ >> + if (info->last && info->end_daddr) >> + rec_daddr = info->end_daddr; >> + >> /* >> * Filter out records that start before our startpoint, if the >> * caller requested that. >> @@ -348,6 +358,21 @@ xfs_getfsmap_helper( >> return error; >> fmr.fmr_offset = XFS_FSB_TO_BB(mp, rec->rm_offset); >> fmr.fmr_length = len_daddr; >> + /* If the start address of the record is before the low key, truncate left. */ >> + if (info->start_daddr > rec_daddr) { >> + trunc_len = info->start_daddr - rec_daddr; >> + fmr.fmr_physical += trunc_len; >> + fmr.fmr_length -= trunc_len; >> + /* need to update the offset in rmapbt. */ >> + if (info->missing_owner == XFS_FMR_OWN_FREE) >> + fmr.fmr_offset += trunc_len; >> + } >> + /* If the end address of the record exceeds the high key, truncate right. */ >> + if (info->end_daddr) { >> + fmr.fmr_length = umin(fmr.fmr_length, info->end_daddr - fmr.fmr_physical); >> + if (fmr.fmr_length == 0) >> + goto out; >> + } >> if (rec->rm_flags & XFS_RMAP_UNWRITTEN) >> fmr.fmr_flags |= FMR_OF_PREALLOC; >> if (rec->rm_flags & XFS_RMAP_ATTR_FORK) >> @@ -364,7 +389,7 @@ xfs_getfsmap_helper( >> >> xfs_getfsmap_format(mp, &fmr, info); >> out: >> - rec_daddr += len_daddr; >> + rec_daddr = fmr.fmr_physical + fmr.fmr_length; >> if (info->next_daddr < rec_daddr) >> info->next_daddr = rec_daddr; >> return 0; >> @@ -655,6 +680,13 @@ __xfs_getfsmap_datadev( >> error = xfs_fsmap_owner_to_rmap(&info->high, &keys[1]); >> if (error) >> break; >> + /* >> + * Set the owner of high_key to the maximum again to >> + * prevent missing intervals during the query. >> + */ >> + if (info->high.rm_owner == 0 && >> + info->missing_owner == XFS_FMR_OWN_FREE) >> + info->high.rm_owner = ULLONG_MAX; >> xfs_getfsmap_set_irec_flags(&info->high, &keys[1]); >> } >> >> @@ -946,6 +978,9 @@ xfs_getfsmap( >> >> info.next_daddr = head->fmh_keys[0].fmr_physical + >> head->fmh_keys[0].fmr_length; >> + /* Assignment is performed only for the first time. */ >> + if (head->fmh_keys[0].fmr_length == 0) >> + info.start_daddr = info.next_daddr; >> info.fsmap_recs = fsmap_recs; >> info.head = head; >> >> @@ -966,8 +1001,10 @@ xfs_getfsmap( >> * low key, zero out the low key so that we get >> * everything from the beginning. >> */ >> - if (handlers[i].dev == head->fmh_keys[1].fmr_device) >> + if (handlers[i].dev == head->fmh_keys[1].fmr_device) { >> dkeys[1] = head->fmh_keys[1]; >> + info.end_daddr = dkeys[1].fmr_physical + dkeys[1].fmr_length; >> + } >> if (handlers[i].dev > head->fmh_keys[0].fmr_device) >> memset(&dkeys[0], 0, sizeof(struct xfs_fsmap)); >> >> @@ -991,6 +1028,7 @@ xfs_getfsmap( >> xfs_trans_cancel(tp); >> tp = NULL; >> info.next_daddr = 0; >> + info.start_daddr = 0; >> } >> >> if (tp) >> -- >> 2.39.2 >> >> >
Hello,
kernel test robot noticed "xfstests.xfs.556.fail" on:
commit: afef0c6f182dcaa5858b95edb6df46b7e4a54824 ("[PATCH V2] xfs: Make the fsmap more precise")
url: https://github.com/intel-lab-lkp/linux/commits/Zizhi-Wo/xfs-Make-the-fsmap-more-precise/20240809-005729
base: https://git.kernel.org/cgit/fs/xfs/xfs-linux.git for-next
patch link: https://lore.kernel.org/all/20240808144759.1330237-1-wozizhi@huawei.com/
patch subject: [PATCH V2] xfs: Make the fsmap more precise
in testcase: xfstests
version: xfstests-x86_64-f5ada754-1_20240812
with following parameters:
disk: 4HDD
fs: xfs
test: xfs-556
compiler: gcc-12
test machine: 4 threads Intel(R) Xeon(R) CPU E3-1225 v5 @ 3.30GHz (Skylake) with 16G memory
(please refer to attached dmesg/kmsg for entire log/backtrace)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202408161111.8e30613b-oliver.sang@intel.com
2024-08-16 01:01:52 export TEST_DIR=/fs/sda1
2024-08-16 01:01:52 export TEST_DEV=/dev/sda1
2024-08-16 01:01:52 export FSTYP=xfs
2024-08-16 01:01:52 export SCRATCH_MNT=/fs/scratch
2024-08-16 01:01:52 mkdir /fs/scratch -p
2024-08-16 01:01:52 export SCRATCH_DEV=/dev/sda4
2024-08-16 01:01:52 export SCRATCH_LOGDEV=/dev/sda2
2024-08-16 01:01:52 export SCRATCH_XFS_LIST_METADATA_FIELDS=u3.sfdir3.hdr.parent.i4
2024-08-16 01:01:52 export SCRATCH_XFS_LIST_FUZZ_VERBS=random
2024-08-16 01:01:52 echo xfs/556
2024-08-16 01:01:52 ./check xfs/556
FSTYP -- xfs (debug)
PLATFORM -- Linux/x86_64 lkp-skl-d06 6.11.0-rc1-00007-gafef0c6f182d #1 SMP PREEMPT_DYNAMIC Fri Aug 16 02:37:27 CST 2024
MKFS_OPTIONS -- -f /dev/sda4
MOUNT_OPTIONS -- /dev/sda4 /fs/scratch
xfs/556 - output mismatch (see /lkp/benchmarks/xfstests/results//xfs/556.out.bad)
--- tests/xfs/556.out 2024-08-12 20:11:27.000000000 +0000
+++ /lkp/benchmarks/xfstests/results//xfs/556.out.bad 2024-08-16 01:02:14.357396417 +0000
@@ -1,12 +1,21 @@
QA output created by 556
Scrub for injected media error (single threaded)
+Corruption: disk offset 106496: media error in unknown owner. (phase6.c line 400)
Unfixable Error: SCRATCH_MNT/a: media error at data offset 2FSB length 1FSB.
SCRATCH_MNT: unfixable errors found: 1
+SCRATCH_MNT: corruptions found: 1
+SCRATCH_MNT: Unmount and run xfs_repair.
...
(Run 'diff -u /lkp/benchmarks/xfstests/tests/xfs/556.out /lkp/benchmarks/xfstests/results//xfs/556.out.bad' to see the entire diff)
Ran: xfs/556
Failures: xfs/556
Failed 1 of 1 tests
The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20240816/202408161111.8e30613b-oliver.sang@intel.com
diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c index 85dbb46452ca..e7bb21497e5c 100644 --- a/fs/xfs/xfs_fsmap.c +++ b/fs/xfs/xfs_fsmap.c @@ -162,6 +162,8 @@ struct xfs_getfsmap_info { xfs_daddr_t next_daddr; /* next daddr we expect */ /* daddr of low fsmap key when we're using the rtbitmap */ xfs_daddr_t low_daddr; + xfs_daddr_t start_daddr; /* daddr of low fsmap key */ + xfs_daddr_t end_daddr; /* daddr of high fsmap key */ u64 missing_owner; /* owner of holes */ u32 dev; /* device id */ /* @@ -276,6 +278,7 @@ xfs_getfsmap_helper( struct xfs_mount *mp = tp->t_mountp; bool shared; int error; + int trunc_len; if (fatal_signal_pending(current)) return -EINTR; @@ -283,6 +286,13 @@ xfs_getfsmap_helper( if (len_daddr == 0) len_daddr = XFS_FSB_TO_BB(mp, rec->rm_blockcount); + /* + * Determine the maximum boundary of the query to prepare for + * subsequent truncation. + */ + if (info->last && info->end_daddr) + rec_daddr = info->end_daddr; + /* * Filter out records that start before our startpoint, if the * caller requested that. @@ -348,6 +358,21 @@ xfs_getfsmap_helper( return error; fmr.fmr_offset = XFS_FSB_TO_BB(mp, rec->rm_offset); fmr.fmr_length = len_daddr; + /* If the start address of the record is before the low key, truncate left. */ + if (info->start_daddr > rec_daddr) { + trunc_len = info->start_daddr - rec_daddr; + fmr.fmr_physical += trunc_len; + fmr.fmr_length -= trunc_len; + /* need to update the offset in rmapbt. */ + if (info->missing_owner == XFS_FMR_OWN_FREE) + fmr.fmr_offset += trunc_len; + } + /* If the end address of the record exceeds the high key, truncate right. */ + if (info->end_daddr) { + fmr.fmr_length = umin(fmr.fmr_length, info->end_daddr - fmr.fmr_physical); + if (fmr.fmr_length == 0) + goto out; + } if (rec->rm_flags & XFS_RMAP_UNWRITTEN) fmr.fmr_flags |= FMR_OF_PREALLOC; if (rec->rm_flags & XFS_RMAP_ATTR_FORK) @@ -364,7 +389,7 @@ xfs_getfsmap_helper( xfs_getfsmap_format(mp, &fmr, info); out: - rec_daddr += len_daddr; + rec_daddr = fmr.fmr_physical + fmr.fmr_length; if (info->next_daddr < rec_daddr) info->next_daddr = rec_daddr; return 0; @@ -655,6 +680,13 @@ __xfs_getfsmap_datadev( error = xfs_fsmap_owner_to_rmap(&info->high, &keys[1]); if (error) break; + /* + * Set the owner of high_key to the maximum again to + * prevent missing intervals during the query. + */ + if (info->high.rm_owner == 0 && + info->missing_owner == XFS_FMR_OWN_FREE) + info->high.rm_owner = ULLONG_MAX; xfs_getfsmap_set_irec_flags(&info->high, &keys[1]); } @@ -946,6 +978,9 @@ xfs_getfsmap( info.next_daddr = head->fmh_keys[0].fmr_physical + head->fmh_keys[0].fmr_length; + /* Assignment is performed only for the first time. */ + if (head->fmh_keys[0].fmr_length == 0) + info.start_daddr = info.next_daddr; info.fsmap_recs = fsmap_recs; info.head = head; @@ -966,8 +1001,10 @@ xfs_getfsmap( * low key, zero out the low key so that we get * everything from the beginning. */ - if (handlers[i].dev == head->fmh_keys[1].fmr_device) + if (handlers[i].dev == head->fmh_keys[1].fmr_device) { dkeys[1] = head->fmh_keys[1]; + info.end_daddr = dkeys[1].fmr_physical + dkeys[1].fmr_length; + } if (handlers[i].dev > head->fmh_keys[0].fmr_device) memset(&dkeys[0], 0, sizeof(struct xfs_fsmap)); @@ -991,6 +1028,7 @@ xfs_getfsmap( xfs_trans_cancel(tp); tp = NULL; info.next_daddr = 0; + info.start_daddr = 0; } if (tp)
In commit 63ef7a35912d ("xfs: fix interval filtering in multi-step fsmap queries"), Darrick has solved a fsmap bug about incorrect filter condition. But I still notice two problems in fsmap: [root@fedora ~]# xfs_io -c 'fsmap -vvvv' /mnt EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL 0: 253:32 [0..7]: static fs metadata 0 (0..7) 8 1: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 2: 253:32 [24..39]: inode btree 0 (24..39) 16 ...... Bug 1: [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt [root@fedora ~]# Normally, we should be able to get [3, 7), but we got nothing. Bug 2: [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL 0: 253:32 [8..23]: per-AG metadata 0 (8..23) 16 Normally, we should be able to get [15, 20), but we obtained a whole segment of extent. The first problem is caused by shifting. When the query interval is before the first extent which can be find in btree, no records can meet the requirement. And the gap will be obtained in the last query. However, rec_daddr is calculated based on the start_block recorded in key[1], which is converted by calling XFS_BB_TO_FSBT. Then if rec_daddr does not exceed info->next_daddr, which means keys[1].fmr_physical >> (mp)->m_blkbb_log <= info->next_daddr, no records will be displayed. In the above example, 3 >> (mp)->m_blkbb_log = 0 and 7 >> (mp)->m_blkbb_log = 0, so the two are reduced to 0 and the gap is ignored: before calculate ----------------> after shifting 3(st) 7(ed) 0(st/ed) |---------| | sector size block size Resolve this issue by introducing the "tail_daddr" field in xfs_getfsmap_info. This records |key[1].fmr_physical + key[1].length| at the granularity of sector. If the current query is the last, the rec_daddr is tail_daddr to prevent missing interval problems caused by shifting. We only need to focus on the last query, because xfs disks are internally aligned with disk blocksize that are powers of two and minimum 512, so there is no problem with shifting in previous queries. The second problem is that the resulting range is not truncated precisely according to the boundary. Currently, the query display mechanism for owner and missing_owner is different. The query of missing_owner (e.g. freespace in rmapbt/ unknown space in bnobt) is obtained by subtraction (gap), which can accurately lock the range. In the query of owner which almostly finded by btree, as long as certain conditions met, the entire interval is recorded, regardless of the starting address of the key[0] and key[1] incoming from the user state. Focus on the following scenario: a b |-------| query c d |----------------|-------------|----------------| missing owner1 owner missing owner2 Currently query is directly displayed as [c, d), the correct display should be [a, b). This problem is solved by calculating max(a, c) and min(b, d) to identify the head and tail of the range. To be able to determine the bounds of the low key, "start_daddr" is introduced in xfs_getfsmap_info. Although in some scenarios, similar results can be achieved without introducing "start_daddr" and relying solely on info->next_daddr (e.g. in bnobt), it is ineffective for overlapping scenarios in rmapbt. After applying this patch, both of the above issues have been fixed (the same applies to boundary queries for the log device and realtime device): 1) [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 3 7' /mnt EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL 0: 253:32 [3..6]: static fs metadata 0 (3..6) 4 2) [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 15 20' /mnt EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL 0: 253:32 [15..19]: per-AG metadata 0 (15..19) 5 Note that due to the current query range being more precise, high.rm_owner needs to be handled carefully. When it is 0, set it to the maximum value to prevent missing intervals in rmapbt. Signed-off-by: Zizhi Wo <wozizhi@huawei.com> --- fs/xfs/xfs_fsmap.c | 42 ++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 40 insertions(+), 2 deletions(-)