| Message ID | 1520410819-32405-3-git-send-email-robbieko@synology.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2018年03月07日 16:20, robbieko wrote: > From: Robbie Ko <robbieko@synology.com> > > [BUG] > Range clone can cause fiemap to return error result. > Like: > # mount /dev/vdb5 /mnt/btrfs > # dd if=/dev/zero bs=16K count=2 oflag=dsync of=/mnt/btrfs/file > # xfs_io -c "fiemap -v" /mnt/btrfs/file > /mnt/btrfs/file: > EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS > 0: [0..63]: 4241424..4241487 64 0x1 > > # cloner -s $((16*1024)) /mnt/btrfs/file /mnt/btrfs/file_clone > # xfs_io -c "fiemap -v" /mnt/btrfs/file > /mnt/btrfs/file: > EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS > 0: [0..63]: 4241424..4241487 64 0x1 > If we clone second file extent, we will get error FLAGS, > SHARED bit is not set. > > [REASON] > Btrfs only checks if the first extent in extent map is shared, > but extent may merge. > > [FIX] > Here we will check each extent with extent map range, > if one of them is shared, extent map is shared. > > [PATCH RESULT] > # xfs_io -c "fiemap -v" /mnt/btrfs/file > /mnt/btrfs/file: > EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS > 0: [0..63]: 4241424..4241487 64 0x2001 > > Signed-off-by: Robbie Ko <robbieko@synology.com> > --- > fs/btrfs/extent_io.c | 146 +++++++++++++++++++++++++++++++++++++++++++++------ > 1 file changed, 131 insertions(+), 15 deletions(-) > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index 066b6df..5c6dca9 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -4394,8 +4394,8 @@ static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo, > */ > if (cache->offset + cache->len == offset && > cache->phys + cache->len == phys && > - (cache->flags & ~FIEMAP_EXTENT_LAST) == > - (flags & ~FIEMAP_EXTENT_LAST)) { > + (cache->flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED)) == > + (flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED))) { > cache->len += len; > cache->flags |= flags; > goto try_submit_last; > @@ -4450,6 +4450,134 @@ static int emit_last_fiemap_cache(struct btrfs_fs_info *fs_info, > return ret; > } > > +/* > + * Helper to check the file range is shared. > + * > + * Fiemap extent will be combined with many extents, so we need to examine > + * each extent, and if shared, the results are shared. > + * > + * Return: 0 if file range is not shared, 1 if it is shared, < 0 on error. > + */ > +static int extent_map_check_shared(struct inode *inode, u64 start, u64 end) > +{ > + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > + struct btrfs_root *root = BTRFS_I(inode)->root; > + int ret = 0; > + struct extent_buffer *leaf; > + struct btrfs_path *path; > + struct btrfs_file_extent_item *fi; > + struct btrfs_key found_key; > + int check_prev = 1; > + int extent_type; > + int shared = 0; > + u64 cur_offset; > + u64 extent_end; > + u64 ino = btrfs_ino(BTRFS_I(inode)); > + u64 disk_bytenr; > + > + path = btrfs_alloc_path(); > + if (!path) { > + return -ENOMEM; > + } > + > + cur_offset = start; > + while (1) { > + ret = btrfs_lookup_file_extent(NULL, root, path, ino, > + cur_offset, 0); > + if (ret < 0) > + goto error; > + if (ret > 0 && path->slots[0] > 0 && check_prev) { > + leaf = path->nodes[0]; > + btrfs_item_key_to_cpu(leaf, &found_key, > + path->slots[0] - 1); > + if (found_key.objectid == ino && > + found_key.type == BTRFS_EXTENT_DATA_KEY) > + path->slots[0]--; > + } > + check_prev = 0; > +next_slot: > + leaf = path->nodes[0]; > + if (path->slots[0] >= btrfs_header_nritems(leaf)) { > + ret = btrfs_next_leaf(root, path); > + if (ret < 0) > + goto error; > + if (ret > 0) > + break; > + leaf = path->nodes[0]; > + } > + > + disk_bytenr = 0; > + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); > + > + if (found_key.objectid > ino) > + break; > + if (WARN_ON_ONCE(found_key.objectid < ino) || > + found_key.type < BTRFS_EXTENT_DATA_KEY) { > + path->slots[0]++; > + goto next_slot; > + } > + if (found_key.type > BTRFS_EXTENT_DATA_KEY || > + found_key.offset > end) > + break; > + > + fi = btrfs_item_ptr(leaf, path->slots[0], > + struct btrfs_file_extent_item); > + extent_type = btrfs_file_extent_type(leaf, fi); > + > + if (extent_type == BTRFS_FILE_EXTENT_REG || > + extent_type == BTRFS_FILE_EXTENT_PREALLOC) { > + disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi); > + extent_end = found_key.offset + > + btrfs_file_extent_num_bytes(leaf, fi); > + if (extent_end <= start) { > + path->slots[0]++; > + goto next_slot; > + } > + if (disk_bytenr == 0) { > + path->slots[0]++; > + goto next_slot; > + } > + > + btrfs_release_path(path); > + > + /* > + * As btrfs supports shared space, this information > + * can be exported to userspace tools via > + * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 > + * then we're just getting a count and we can skip the > + * lookup stuff. > + */ > + ret = btrfs_check_shared(root, > + ino, disk_bytenr); > + if (ret < 0) > + goto error; > + if (ret) > + shared = 1; > + ret = 0; > + if (shared) { > + break; > + } > + } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) { > + extent_end = found_key.offset + > + btrfs_file_extent_inline_len(leaf, > + path->slots[0], fi); > + extent_end = ALIGN(extent_end, fs_info->sectorsize); > + path->slots[0]++; > + goto next_slot; > + } else { > + BUG_ON(1); > + } > + cur_offset = extent_end; > + if (cur_offset > end) > + break; > + } > + > + ret = 0; > +error: > + btrfs_free_path(path); > + return !ret ? shared : ret; > +} > + > int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > __u64 start, __u64 len, get_extent_t *get_extent) > { > @@ -4587,19 +4715,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > flags |= (FIEMAP_EXTENT_DELALLOC | > FIEMAP_EXTENT_UNKNOWN); > } else if (fieinfo->fi_extents_max) { > - u64 bytenr = em->block_start - > - (em->start - em->orig_start); > - > - /* > - * As btrfs supports shared space, this information > - * can be exported to userspace tools via > - * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 > - * then we're just getting a count and we can skip the > - * lookup stuff. > - */ > - ret = btrfs_check_shared(root, > - btrfs_ino(BTRFS_I(inode)), > - bytenr); Since we're going to use the whole extent to determine the SHARED flags, what about just passing the extent bytenr into btrfs_check_shared? In that case I think we could get correct shared flag without using another helper function. (IIRC it's em->block_start) Thanks, Qu > + ret = extent_map_check_shared(inode, em->start, extent_map_end(em) - 1); > if (ret < 0) > goto out_free; > if (ret) > -- > 1.9.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
On 2018年03月07日 18:33, Qu Wenruo wrote: > > > On 2018年03月07日 16:20, robbieko wrote: >> From: Robbie Ko <robbieko@synology.com> >> >> [BUG] >> Range clone can cause fiemap to return error result. >> Like: >> # mount /dev/vdb5 /mnt/btrfs >> # dd if=/dev/zero bs=16K count=2 oflag=dsync of=/mnt/btrfs/file >> # xfs_io -c "fiemap -v" /mnt/btrfs/file >> /mnt/btrfs/file: >> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >> 0: [0..63]: 4241424..4241487 64 0x1 >> >> # cloner -s $((16*1024)) /mnt/btrfs/file /mnt/btrfs/file_clone >> # xfs_io -c "fiemap -v" /mnt/btrfs/file >> /mnt/btrfs/file: >> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >> 0: [0..63]: 4241424..4241487 64 0x1 >> If we clone second file extent, we will get error FLAGS, >> SHARED bit is not set. >> >> [REASON] >> Btrfs only checks if the first extent in extent map is shared, >> but extent may merge. >> >> [FIX] >> Here we will check each extent with extent map range, >> if one of them is shared, extent map is shared. >> >> [PATCH RESULT] >> # xfs_io -c "fiemap -v" /mnt/btrfs/file >> /mnt/btrfs/file: >> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >> 0: [0..63]: 4241424..4241487 64 0x2001 >> >> Signed-off-by: Robbie Ko <robbieko@synology.com> >> --- >> fs/btrfs/extent_io.c | 146 +++++++++++++++++++++++++++++++++++++++++++++------ >> 1 file changed, 131 insertions(+), 15 deletions(-) >> >> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c >> index 066b6df..5c6dca9 100644 >> --- a/fs/btrfs/extent_io.c >> +++ b/fs/btrfs/extent_io.c >> @@ -4394,8 +4394,8 @@ static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo, >> */ >> if (cache->offset + cache->len == offset && >> cache->phys + cache->len == phys && >> - (cache->flags & ~FIEMAP_EXTENT_LAST) == >> - (flags & ~FIEMAP_EXTENT_LAST)) { >> + (cache->flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED)) == >> + (flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED))) { >> cache->len += len; >> cache->flags |= flags; >> goto try_submit_last; >> @@ -4450,6 +4450,134 @@ static int emit_last_fiemap_cache(struct btrfs_fs_info *fs_info, >> return ret; >> } >> >> +/* >> + * Helper to check the file range is shared. >> + * >> + * Fiemap extent will be combined with many extents, so we need to examine >> + * each extent, and if shared, the results are shared. >> + * >> + * Return: 0 if file range is not shared, 1 if it is shared, < 0 on error. >> + */ >> +static int extent_map_check_shared(struct inode *inode, u64 start, u64 end) >> +{ >> + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); >> + struct btrfs_root *root = BTRFS_I(inode)->root; >> + int ret = 0; >> + struct extent_buffer *leaf; >> + struct btrfs_path *path; >> + struct btrfs_file_extent_item *fi; >> + struct btrfs_key found_key; >> + int check_prev = 1; >> + int extent_type; >> + int shared = 0; >> + u64 cur_offset; >> + u64 extent_end; >> + u64 ino = btrfs_ino(BTRFS_I(inode)); >> + u64 disk_bytenr; >> + >> + path = btrfs_alloc_path(); >> + if (!path) { >> + return -ENOMEM; >> + } >> + >> + cur_offset = start; >> + while (1) { >> + ret = btrfs_lookup_file_extent(NULL, root, path, ino, >> + cur_offset, 0); >> + if (ret < 0) >> + goto error; >> + if (ret > 0 && path->slots[0] > 0 && check_prev) { >> + leaf = path->nodes[0]; >> + btrfs_item_key_to_cpu(leaf, &found_key, >> + path->slots[0] - 1); >> + if (found_key.objectid == ino && >> + found_key.type == BTRFS_EXTENT_DATA_KEY) >> + path->slots[0]--; >> + } >> + check_prev = 0; >> +next_slot: >> + leaf = path->nodes[0]; >> + if (path->slots[0] >= btrfs_header_nritems(leaf)) { >> + ret = btrfs_next_leaf(root, path); >> + if (ret < 0) >> + goto error; >> + if (ret > 0) >> + break; >> + leaf = path->nodes[0]; >> + } >> + >> + disk_bytenr = 0; >> + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); >> + >> + if (found_key.objectid > ino) >> + break; >> + if (WARN_ON_ONCE(found_key.objectid < ino) || >> + found_key.type < BTRFS_EXTENT_DATA_KEY) { >> + path->slots[0]++; >> + goto next_slot; >> + } >> + if (found_key.type > BTRFS_EXTENT_DATA_KEY || >> + found_key.offset > end) >> + break; >> + >> + fi = btrfs_item_ptr(leaf, path->slots[0], >> + struct btrfs_file_extent_item); >> + extent_type = btrfs_file_extent_type(leaf, fi); >> + >> + if (extent_type == BTRFS_FILE_EXTENT_REG || >> + extent_type == BTRFS_FILE_EXTENT_PREALLOC) { >> + disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi); >> + extent_end = found_key.offset + >> + btrfs_file_extent_num_bytes(leaf, fi); >> + if (extent_end <= start) { >> + path->slots[0]++; >> + goto next_slot; >> + } >> + if (disk_bytenr == 0) { >> + path->slots[0]++; >> + goto next_slot; >> + } >> + >> + btrfs_release_path(path); >> + >> + /* >> + * As btrfs supports shared space, this information >> + * can be exported to userspace tools via >> + * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 >> + * then we're just getting a count and we can skip the >> + * lookup stuff. >> + */ >> + ret = btrfs_check_shared(root, >> + ino, disk_bytenr); >> + if (ret < 0) >> + goto error; >> + if (ret) >> + shared = 1; >> + ret = 0; >> + if (shared) { >> + break; >> + } >> + } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) { >> + extent_end = found_key.offset + >> + btrfs_file_extent_inline_len(leaf, >> + path->slots[0], fi); >> + extent_end = ALIGN(extent_end, fs_info->sectorsize); >> + path->slots[0]++; >> + goto next_slot; >> + } else { >> + BUG_ON(1); >> + } >> + cur_offset = extent_end; >> + if (cur_offset > end) >> + break; >> + } >> + >> + ret = 0; >> +error: >> + btrfs_free_path(path); >> + return !ret ? shared : ret; >> +} >> + >> int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, >> __u64 start, __u64 len, get_extent_t *get_extent) >> { >> @@ -4587,19 +4715,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, >> flags |= (FIEMAP_EXTENT_DELALLOC | >> FIEMAP_EXTENT_UNKNOWN); >> } else if (fieinfo->fi_extents_max) { >> - u64 bytenr = em->block_start - >> - (em->start - em->orig_start); >> - >> - /* >> - * As btrfs supports shared space, this information >> - * can be exported to userspace tools via >> - * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 >> - * then we're just getting a count and we can skip the >> - * lookup stuff. >> - */ >> - ret = btrfs_check_shared(root, >> - btrfs_ino(BTRFS_I(inode)), >> - bytenr); > > Since we're going to use the whole extent to determine the SHARED flags, > what about just passing the extent bytenr into btrfs_check_shared? > > In that case I think we could get correct shared flag without using > another helper function. > (IIRC it's em->block_start) Well, it's not em->block_start, but a little more complex. (For compressed one it's em->block_start, but for plaintext one, it's more complex) em->block_start = file_extent_disk_bytenr + file_extent_file_extent_offset We need extra calculation to determine the real extent bytenr (file_extent_disk_bytenr). IIRC the correct calculation would be: file_extent_disk_bytenr = em->block_start - em->start + em->orig_start. (Who thought out such anti-human calculation for extent map?!) Thanks, Qu > > Thanks, > Qu > >> + ret = extent_map_check_shared(inode, em->start, extent_map_end(em) - 1); >> if (ret < 0) >> goto out_free; >> if (ret) >> -- >> 1.9.1 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >
Qu Wenruo 於 2018-03-07 18:42 寫到: > On 2018年03月07日 18:33, Qu Wenruo wrote: >> >> >> On 2018年03月07日 16:20, robbieko wrote: >>> From: Robbie Ko <robbieko@synology.com> >>> >>> [BUG] >>> Range clone can cause fiemap to return error result. >>> Like: >>> # mount /dev/vdb5 /mnt/btrfs >>> # dd if=/dev/zero bs=16K count=2 oflag=dsync of=/mnt/btrfs/file >>> # xfs_io -c "fiemap -v" /mnt/btrfs/file >>> /mnt/btrfs/file: >>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>> 0: [0..63]: 4241424..4241487 64 0x1 >>> >>> # cloner -s $((16*1024)) /mnt/btrfs/file /mnt/btrfs/file_clone >>> # xfs_io -c "fiemap -v" /mnt/btrfs/file >>> /mnt/btrfs/file: >>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>> 0: [0..63]: 4241424..4241487 64 0x1 >>> If we clone second file extent, we will get error FLAGS, >>> SHARED bit is not set. >>> >>> [REASON] >>> Btrfs only checks if the first extent in extent map is shared, >>> but extent may merge. >>> >>> [FIX] >>> Here we will check each extent with extent map range, >>> if one of them is shared, extent map is shared. >>> >>> [PATCH RESULT] >>> # xfs_io -c "fiemap -v" /mnt/btrfs/file >>> /mnt/btrfs/file: >>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>> 0: [0..63]: 4241424..4241487 64 0x2001 >>> >>> Signed-off-by: Robbie Ko <robbieko@synology.com> >>> --- >>> fs/btrfs/extent_io.c | 146 >>> +++++++++++++++++++++++++++++++++++++++++++++------ >>> 1 file changed, 131 insertions(+), 15 deletions(-) >>> >>> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c >>> index 066b6df..5c6dca9 100644 >>> --- a/fs/btrfs/extent_io.c >>> +++ b/fs/btrfs/extent_io.c >>> @@ -4394,8 +4394,8 @@ static int emit_fiemap_extent(struct >>> fiemap_extent_info *fieinfo, >>> */ >>> if (cache->offset + cache->len == offset && >>> cache->phys + cache->len == phys && >>> - (cache->flags & ~FIEMAP_EXTENT_LAST) == >>> - (flags & ~FIEMAP_EXTENT_LAST)) { >>> + (cache->flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED)) == >>> + (flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED))) { >>> cache->len += len; >>> cache->flags |= flags; >>> goto try_submit_last; >>> @@ -4450,6 +4450,134 @@ static int emit_last_fiemap_cache(struct >>> btrfs_fs_info *fs_info, >>> return ret; >>> } >>> >>> +/* >>> + * Helper to check the file range is shared. >>> + * >>> + * Fiemap extent will be combined with many extents, so we need to >>> examine >>> + * each extent, and if shared, the results are shared. >>> + * >>> + * Return: 0 if file range is not shared, 1 if it is shared, < 0 on >>> error. >>> + */ >>> +static int extent_map_check_shared(struct inode *inode, u64 start, >>> u64 end) >>> +{ >>> + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); >>> + struct btrfs_root *root = BTRFS_I(inode)->root; >>> + int ret = 0; >>> + struct extent_buffer *leaf; >>> + struct btrfs_path *path; >>> + struct btrfs_file_extent_item *fi; >>> + struct btrfs_key found_key; >>> + int check_prev = 1; >>> + int extent_type; >>> + int shared = 0; >>> + u64 cur_offset; >>> + u64 extent_end; >>> + u64 ino = btrfs_ino(BTRFS_I(inode)); >>> + u64 disk_bytenr; >>> + >>> + path = btrfs_alloc_path(); >>> + if (!path) { >>> + return -ENOMEM; >>> + } >>> + >>> + cur_offset = start; >>> + while (1) { >>> + ret = btrfs_lookup_file_extent(NULL, root, path, ino, >>> + cur_offset, 0); >>> + if (ret < 0) >>> + goto error; >>> + if (ret > 0 && path->slots[0] > 0 && check_prev) { >>> + leaf = path->nodes[0]; >>> + btrfs_item_key_to_cpu(leaf, &found_key, >>> + path->slots[0] - 1); >>> + if (found_key.objectid == ino && >>> + found_key.type == BTRFS_EXTENT_DATA_KEY) >>> + path->slots[0]--; >>> + } >>> + check_prev = 0; >>> +next_slot: >>> + leaf = path->nodes[0]; >>> + if (path->slots[0] >= btrfs_header_nritems(leaf)) { >>> + ret = btrfs_next_leaf(root, path); >>> + if (ret < 0) >>> + goto error; >>> + if (ret > 0) >>> + break; >>> + leaf = path->nodes[0]; >>> + } >>> + >>> + disk_bytenr = 0; >>> + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); >>> + >>> + if (found_key.objectid > ino) >>> + break; >>> + if (WARN_ON_ONCE(found_key.objectid < ino) || >>> + found_key.type < BTRFS_EXTENT_DATA_KEY) { >>> + path->slots[0]++; >>> + goto next_slot; >>> + } >>> + if (found_key.type > BTRFS_EXTENT_DATA_KEY || >>> + found_key.offset > end) >>> + break; >>> + >>> + fi = btrfs_item_ptr(leaf, path->slots[0], >>> + struct btrfs_file_extent_item); >>> + extent_type = btrfs_file_extent_type(leaf, fi); >>> + >>> + if (extent_type == BTRFS_FILE_EXTENT_REG || >>> + extent_type == BTRFS_FILE_EXTENT_PREALLOC) { >>> + disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi); >>> + extent_end = found_key.offset + >>> + btrfs_file_extent_num_bytes(leaf, fi); >>> + if (extent_end <= start) { >>> + path->slots[0]++; >>> + goto next_slot; >>> + } >>> + if (disk_bytenr == 0) { >>> + path->slots[0]++; >>> + goto next_slot; >>> + } >>> + >>> + btrfs_release_path(path); >>> + >>> + /* >>> + * As btrfs supports shared space, this information >>> + * can be exported to userspace tools via >>> + * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 >>> + * then we're just getting a count and we can skip the >>> + * lookup stuff. >>> + */ >>> + ret = btrfs_check_shared(root, >>> + ino, disk_bytenr); >>> + if (ret < 0) >>> + goto error; >>> + if (ret) >>> + shared = 1; >>> + ret = 0; >>> + if (shared) { >>> + break; >>> + } >>> + } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) { >>> + extent_end = found_key.offset + >>> + btrfs_file_extent_inline_len(leaf, >>> + path->slots[0], fi); >>> + extent_end = ALIGN(extent_end, fs_info->sectorsize); >>> + path->slots[0]++; >>> + goto next_slot; >>> + } else { >>> + BUG_ON(1); >>> + } >>> + cur_offset = extent_end; >>> + if (cur_offset > end) >>> + break; >>> + } >>> + >>> + ret = 0; >>> +error: >>> + btrfs_free_path(path); >>> + return !ret ? shared : ret; >>> +} >>> + >>> int extent_fiemap(struct inode *inode, struct fiemap_extent_info >>> *fieinfo, >>> __u64 start, __u64 len, get_extent_t *get_extent) >>> { >>> @@ -4587,19 +4715,7 @@ int extent_fiemap(struct inode *inode, struct >>> fiemap_extent_info *fieinfo, >>> flags |= (FIEMAP_EXTENT_DELALLOC | >>> FIEMAP_EXTENT_UNKNOWN); >>> } else if (fieinfo->fi_extents_max) { >>> - u64 bytenr = em->block_start - >>> - (em->start - em->orig_start); >>> - >>> - /* >>> - * As btrfs supports shared space, this information >>> - * can be exported to userspace tools via >>> - * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 >>> - * then we're just getting a count and we can skip the >>> - * lookup stuff. >>> - */ >>> - ret = btrfs_check_shared(root, >>> - btrfs_ino(BTRFS_I(inode)), >>> - bytenr); >> >> Since we're going to use the whole extent to determine the SHARED >> flags, >> what about just passing the extent bytenr into btrfs_check_shared? >> >> In that case I think we could get correct shared flag without using >> another helper function. >> (IIRC it's em->block_start) > > Well, it's not em->block_start, but a little more complex. > (For compressed one it's em->block_start, but for plaintext one, it's > more complex) > > em->block_start = file_extent_disk_bytenr + > file_extent_file_extent_offset > > We need extra calculation to determine the real extent bytenr > (file_extent_disk_bytenr). > > IIRC the correct calculation would be: > file_extent_disk_bytenr = em->block_start - em->start + em->orig_start. > > (Who thought out such anti-human calculation for extent map?!) > > Thanks, > Qu dd if=/dev/zero bs=16K count=4 oflag=dsync of=file btrfs-debugfs -f file (276 0): ram 16384 disk 2171609088 disk_size 16384 (276 16384): ram 16384 disk 2171625472 disk_size 16384 (276 32768): ram 16384 disk 2171641856 disk_size 16384 (276 49152): ram 16384 disk 2171658240 disk_size 16384 file: file extents 4 disk size 65536 logical size 65536 ratio 1.00 xfs_io -c "fiemap -v" file file: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..127]: 4241424..4241551 128 0x1 My point is that we have only one extent_map, but in fact it can correspond to many extents and each one has the potential to be cloned so we need to examine each one individually. >> >> Thanks, >> Qu >> >>> + ret = extent_map_check_shared(inode, em->start, >>> extent_map_end(em) - 1); >>> if (ret < 0) >>> goto out_free; >>> if (ret) >>> -- >>> 1.9.1 >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe >>> linux-btrfs" in >>> the body of a message to majordomo@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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2018年03月07日 19:01, robbieko wrote: > Qu Wenruo 於 2018-03-07 18:42 寫到: >> On 2018年03月07日 18:33, Qu Wenruo wrote: >>> >>> >>> On 2018年03月07日 16:20, robbieko wrote: >>>> From: Robbie Ko <robbieko@synology.com> >>>> >>>> [BUG] >>>> Range clone can cause fiemap to return error result. >>>> Like: >>>> # mount /dev/vdb5 /mnt/btrfs >>>> # dd if=/dev/zero bs=16K count=2 oflag=dsync of=/mnt/btrfs/file >>>> # xfs_io -c "fiemap -v" /mnt/btrfs/file >>>> /mnt/btrfs/file: >>>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>>> 0: [0..63]: 4241424..4241487 64 0x1 >>>> >>>> # cloner -s $((16*1024)) /mnt/btrfs/file /mnt/btrfs/file_clone >>>> # xfs_io -c "fiemap -v" /mnt/btrfs/file >>>> /mnt/btrfs/file: >>>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>>> 0: [0..63]: 4241424..4241487 64 0x1 >>>> If we clone second file extent, we will get error FLAGS, >>>> SHARED bit is not set. >>>> >>>> [REASON] >>>> Btrfs only checks if the first extent in extent map is shared, >>>> but extent may merge. >>>> >>>> [FIX] >>>> Here we will check each extent with extent map range, >>>> if one of them is shared, extent map is shared. >>>> >>>> [PATCH RESULT] >>>> # xfs_io -c "fiemap -v" /mnt/btrfs/file >>>> /mnt/btrfs/file: >>>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>>> 0: [0..63]: 4241424..4241487 64 0x2001 >>>> >>>> Signed-off-by: Robbie Ko <robbieko@synology.com> >>>> --- >>>> fs/btrfs/extent_io.c | 146 >>>> +++++++++++++++++++++++++++++++++++++++++++++------ >>>> 1 file changed, 131 insertions(+), 15 deletions(-) >>>> >>>> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c >>>> index 066b6df..5c6dca9 100644 >>>> --- a/fs/btrfs/extent_io.c >>>> +++ b/fs/btrfs/extent_io.c >>>> @@ -4394,8 +4394,8 @@ static int emit_fiemap_extent(struct >>>> fiemap_extent_info *fieinfo, >>>> */ >>>> if (cache->offset + cache->len == offset && >>>> cache->phys + cache->len == phys && >>>> - (cache->flags & ~FIEMAP_EXTENT_LAST) == >>>> - (flags & ~FIEMAP_EXTENT_LAST)) { >>>> + (cache->flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED)) == >>>> + (flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED))) { >>>> cache->len += len; >>>> cache->flags |= flags; >>>> goto try_submit_last; >>>> @@ -4450,6 +4450,134 @@ static int emit_last_fiemap_cache(struct >>>> btrfs_fs_info *fs_info, >>>> return ret; >>>> } >>>> >>>> +/* >>>> + * Helper to check the file range is shared. >>>> + * >>>> + * Fiemap extent will be combined with many extents, so we need to >>>> examine >>>> + * each extent, and if shared, the results are shared. >>>> + * >>>> + * Return: 0 if file range is not shared, 1 if it is shared, < 0 on >>>> error. >>>> + */ >>>> +static int extent_map_check_shared(struct inode *inode, u64 start, >>>> u64 end) >>>> +{ >>>> + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); >>>> + struct btrfs_root *root = BTRFS_I(inode)->root; >>>> + int ret = 0; >>>> + struct extent_buffer *leaf; >>>> + struct btrfs_path *path; >>>> + struct btrfs_file_extent_item *fi; >>>> + struct btrfs_key found_key; >>>> + int check_prev = 1; >>>> + int extent_type; >>>> + int shared = 0; >>>> + u64 cur_offset; >>>> + u64 extent_end; >>>> + u64 ino = btrfs_ino(BTRFS_I(inode)); >>>> + u64 disk_bytenr; >>>> + >>>> + path = btrfs_alloc_path(); >>>> + if (!path) { >>>> + return -ENOMEM; >>>> + } >>>> + >>>> + cur_offset = start; >>>> + while (1) { >>>> + ret = btrfs_lookup_file_extent(NULL, root, path, ino, >>>> + cur_offset, 0); >>>> + if (ret < 0) >>>> + goto error; >>>> + if (ret > 0 && path->slots[0] > 0 && check_prev) { >>>> + leaf = path->nodes[0]; >>>> + btrfs_item_key_to_cpu(leaf, &found_key, >>>> + path->slots[0] - 1); >>>> + if (found_key.objectid == ino && >>>> + found_key.type == BTRFS_EXTENT_DATA_KEY) >>>> + path->slots[0]--; >>>> + } >>>> + check_prev = 0; >>>> +next_slot: >>>> + leaf = path->nodes[0]; >>>> + if (path->slots[0] >= btrfs_header_nritems(leaf)) { >>>> + ret = btrfs_next_leaf(root, path); >>>> + if (ret < 0) >>>> + goto error; >>>> + if (ret > 0) >>>> + break; >>>> + leaf = path->nodes[0]; >>>> + } >>>> + >>>> + disk_bytenr = 0; >>>> + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); >>>> + >>>> + if (found_key.objectid > ino) >>>> + break; >>>> + if (WARN_ON_ONCE(found_key.objectid < ino) || >>>> + found_key.type < BTRFS_EXTENT_DATA_KEY) { >>>> + path->slots[0]++; >>>> + goto next_slot; >>>> + } >>>> + if (found_key.type > BTRFS_EXTENT_DATA_KEY || >>>> + found_key.offset > end) >>>> + break; >>>> + >>>> + fi = btrfs_item_ptr(leaf, path->slots[0], >>>> + struct btrfs_file_extent_item); >>>> + extent_type = btrfs_file_extent_type(leaf, fi); >>>> + >>>> + if (extent_type == BTRFS_FILE_EXTENT_REG || >>>> + extent_type == BTRFS_FILE_EXTENT_PREALLOC) { >>>> + disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi); >>>> + extent_end = found_key.offset + >>>> + btrfs_file_extent_num_bytes(leaf, fi); >>>> + if (extent_end <= start) { >>>> + path->slots[0]++; >>>> + goto next_slot; >>>> + } >>>> + if (disk_bytenr == 0) { >>>> + path->slots[0]++; >>>> + goto next_slot; >>>> + } >>>> + >>>> + btrfs_release_path(path); >>>> + >>>> + /* >>>> + * As btrfs supports shared space, this information >>>> + * can be exported to userspace tools via >>>> + * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 >>>> + * then we're just getting a count and we can skip the >>>> + * lookup stuff. >>>> + */ >>>> + ret = btrfs_check_shared(root, >>>> + ino, disk_bytenr); >>>> + if (ret < 0) >>>> + goto error; >>>> + if (ret) >>>> + shared = 1; >>>> + ret = 0; >>>> + if (shared) { >>>> + break; >>>> + } >>>> + } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) { >>>> + extent_end = found_key.offset + >>>> + btrfs_file_extent_inline_len(leaf, >>>> + path->slots[0], fi); >>>> + extent_end = ALIGN(extent_end, fs_info->sectorsize); >>>> + path->slots[0]++; >>>> + goto next_slot; >>>> + } else { >>>> + BUG_ON(1); >>>> + } >>>> + cur_offset = extent_end; >>>> + if (cur_offset > end) >>>> + break; >>>> + } >>>> + >>>> + ret = 0; >>>> +error: >>>> + btrfs_free_path(path); >>>> + return !ret ? shared : ret; >>>> +} >>>> + >>>> int extent_fiemap(struct inode *inode, struct fiemap_extent_info >>>> *fieinfo, >>>> __u64 start, __u64 len, get_extent_t *get_extent) >>>> { >>>> @@ -4587,19 +4715,7 @@ int extent_fiemap(struct inode *inode, struct >>>> fiemap_extent_info *fieinfo, >>>> flags |= (FIEMAP_EXTENT_DELALLOC | >>>> FIEMAP_EXTENT_UNKNOWN); >>>> } else if (fieinfo->fi_extents_max) { >>>> - u64 bytenr = em->block_start - >>>> - (em->start - em->orig_start); >>>> - >>>> - /* >>>> - * As btrfs supports shared space, this information >>>> - * can be exported to userspace tools via >>>> - * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 >>>> - * then we're just getting a count and we can skip the >>>> - * lookup stuff. >>>> - */ >>>> - ret = btrfs_check_shared(root, >>>> - btrfs_ino(BTRFS_I(inode)), >>>> - bytenr); >>> >>> Since we're going to use the whole extent to determine the SHARED flags, >>> what about just passing the extent bytenr into btrfs_check_shared? >>> >>> In that case I think we could get correct shared flag without using >>> another helper function. >>> (IIRC it's em->block_start) >> >> Well, it's not em->block_start, but a little more complex. >> (For compressed one it's em->block_start, but for plaintext one, it's >> more complex) >> >> em->block_start = file_extent_disk_bytenr + >> file_extent_file_extent_offset >> >> We need extra calculation to determine the real extent bytenr >> (file_extent_disk_bytenr). >> >> IIRC the correct calculation would be: >> file_extent_disk_bytenr = em->block_start - em->start + em->orig_start. >> >> (Who thought out such anti-human calculation for extent map?!) >> >> Thanks, >> Qu > > dd if=/dev/zero bs=16K count=4 oflag=dsync of=file > > btrfs-debugfs -f file > (276 0): ram 16384 disk 2171609088 disk_size 16384 > (276 16384): ram 16384 disk 2171625472 disk_size 16384 > (276 32768): ram 16384 disk 2171641856 disk_size 16384 > (276 49152): ram 16384 disk 2171658240 disk_size 16384 > file: file extents 4 disk size 65536 logical size 65536 ratio 1.00 > > xfs_io -c "fiemap -v" file > file: > EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS > 0: [0..127]: 4241424..4241551 128 0x1 > > My point is that we have only one extent_map, > but in fact it can correspond to many extents > and each one has the potential to be cloned > so we need to examine each one individually. Right, I missed this point. SHARED flag is determined after extent map merge, so here we can't rely on em here. So the current helper function looks valid, unless we have method to access the original extent map. Thanks, Qu > > >>> >>> Thanks, >>> Qu >>> >>>> + ret = extent_map_check_shared(inode, em->start, >>>> extent_map_end(em) - 1); >>>> if (ret < 0) >>>> goto out_free; >>>> if (ret) >>>> -- >>>> 1.9.1 >>>> >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe >>>> linux-btrfs" in >>>> the body of a message to majordomo@vger.kernel.org >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> >>> >
On 7.03.2018 13:18, Qu Wenruo wrote: > > > On 2018年03月07日 19:01, robbieko wrote: >> Qu Wenruo 於 2018-03-07 18:42 寫到: >>> On 2018年03月07日 18:33, Qu Wenruo wrote: >>>> >>>> >>>> On 2018年03月07日 16:20, robbieko wrote: >>>>> From: Robbie Ko <robbieko@synology.com> >>>>> >>>>> [BUG] >>>>> Range clone can cause fiemap to return error result. >>>>> Like: >>>>> # mount /dev/vdb5 /mnt/btrfs >>>>> # dd if=/dev/zero bs=16K count=2 oflag=dsync of=/mnt/btrfs/file >>>>> # xfs_io -c "fiemap -v" /mnt/btrfs/file >>>>> /mnt/btrfs/file: >>>>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>>>> 0: [0..63]: 4241424..4241487 64 0x1 >>>>> >>>>> # cloner -s $((16*1024)) /mnt/btrfs/file /mnt/btrfs/file_clone >>>>> # xfs_io -c "fiemap -v" /mnt/btrfs/file >>>>> /mnt/btrfs/file: >>>>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>>>> 0: [0..63]: 4241424..4241487 64 0x1 >>>>> If we clone second file extent, we will get error FLAGS, >>>>> SHARED bit is not set. >>>>> >>>>> [REASON] >>>>> Btrfs only checks if the first extent in extent map is shared, >>>>> but extent may merge. >>>>> >>>>> [FIX] >>>>> Here we will check each extent with extent map range, >>>>> if one of them is shared, extent map is shared. >>>>> >>>>> [PATCH RESULT] >>>>> # xfs_io -c "fiemap -v" /mnt/btrfs/file >>>>> /mnt/btrfs/file: >>>>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>>>> 0: [0..63]: 4241424..4241487 64 0x2001 >>>>> >>>>> Signed-off-by: Robbie Ko <robbieko@synology.com> >>>>> --- >>>>> fs/btrfs/extent_io.c | 146 >>>>> +++++++++++++++++++++++++++++++++++++++++++++------ >>>>> 1 file changed, 131 insertions(+), 15 deletions(-) >>>>> >>>>> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c >>>>> index 066b6df..5c6dca9 100644 >>>>> --- a/fs/btrfs/extent_io.c >>>>> +++ b/fs/btrfs/extent_io.c >>>>> @@ -4394,8 +4394,8 @@ static int emit_fiemap_extent(struct >>>>> fiemap_extent_info *fieinfo, >>>>> */ >>>>> if (cache->offset + cache->len == offset && >>>>> cache->phys + cache->len == phys && >>>>> - (cache->flags & ~FIEMAP_EXTENT_LAST) == >>>>> - (flags & ~FIEMAP_EXTENT_LAST)) { >>>>> + (cache->flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED)) == >>>>> + (flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED))) { >>>>> cache->len += len; >>>>> cache->flags |= flags; >>>>> goto try_submit_last; >>>>> @@ -4450,6 +4450,134 @@ static int emit_last_fiemap_cache(struct >>>>> btrfs_fs_info *fs_info, >>>>> return ret; >>>>> } >>>>> >>>>> +/* >>>>> + * Helper to check the file range is shared. >>>>> + * >>>>> + * Fiemap extent will be combined with many extents, so we need to >>>>> examine >>>>> + * each extent, and if shared, the results are shared. >>>>> + * >>>>> + * Return: 0 if file range is not shared, 1 if it is shared, < 0 on >>>>> error. >>>>> + */ >>>>> +static int extent_map_check_shared(struct inode *inode, u64 start, >>>>> u64 end) >>>>> +{ >>>>> + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); >>>>> + struct btrfs_root *root = BTRFS_I(inode)->root; >>>>> + int ret = 0; >>>>> + struct extent_buffer *leaf; >>>>> + struct btrfs_path *path; >>>>> + struct btrfs_file_extent_item *fi; >>>>> + struct btrfs_key found_key; >>>>> + int check_prev = 1; >>>>> + int extent_type; >>>>> + int shared = 0; >>>>> + u64 cur_offset; >>>>> + u64 extent_end; >>>>> + u64 ino = btrfs_ino(BTRFS_I(inode)); >>>>> + u64 disk_bytenr; >>>>> + >>>>> + path = btrfs_alloc_path(); >>>>> + if (!path) { >>>>> + return -ENOMEM; >>>>> + } >>>>> + >>>>> + cur_offset = start; >>>>> + while (1) { >>>>> + ret = btrfs_lookup_file_extent(NULL, root, path, ino, >>>>> + cur_offset, 0); >>>>> + if (ret < 0) >>>>> + goto error; >>>>> + if (ret > 0 && path->slots[0] > 0 && check_prev) { >>>>> + leaf = path->nodes[0]; >>>>> + btrfs_item_key_to_cpu(leaf, &found_key, >>>>> + path->slots[0] - 1); >>>>> + if (found_key.objectid == ino && >>>>> + found_key.type == BTRFS_EXTENT_DATA_KEY) >>>>> + path->slots[0]--; >>>>> + } >>>>> + check_prev = 0; >>>>> +next_slot: >>>>> + leaf = path->nodes[0]; >>>>> + if (path->slots[0] >= btrfs_header_nritems(leaf)) { >>>>> + ret = btrfs_next_leaf(root, path); >>>>> + if (ret < 0) >>>>> + goto error; >>>>> + if (ret > 0) >>>>> + break; >>>>> + leaf = path->nodes[0]; >>>>> + } >>>>> + >>>>> + disk_bytenr = 0; >>>>> + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); >>>>> + >>>>> + if (found_key.objectid > ino) >>>>> + break; >>>>> + if (WARN_ON_ONCE(found_key.objectid < ino) || >>>>> + found_key.type < BTRFS_EXTENT_DATA_KEY) { >>>>> + path->slots[0]++; >>>>> + goto next_slot; >>>>> + } >>>>> + if (found_key.type > BTRFS_EXTENT_DATA_KEY || >>>>> + found_key.offset > end) >>>>> + break; >>>>> + >>>>> + fi = btrfs_item_ptr(leaf, path->slots[0], >>>>> + struct btrfs_file_extent_item); >>>>> + extent_type = btrfs_file_extent_type(leaf, fi); >>>>> + >>>>> + if (extent_type == BTRFS_FILE_EXTENT_REG || >>>>> + extent_type == BTRFS_FILE_EXTENT_PREALLOC) { >>>>> + disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi); >>>>> + extent_end = found_key.offset + >>>>> + btrfs_file_extent_num_bytes(leaf, fi); >>>>> + if (extent_end <= start) { >>>>> + path->slots[0]++; >>>>> + goto next_slot; >>>>> + } >>>>> + if (disk_bytenr == 0) { >>>>> + path->slots[0]++; >>>>> + goto next_slot; >>>>> + } >>>>> + >>>>> + btrfs_release_path(path); >>>>> + >>>>> + /* >>>>> + * As btrfs supports shared space, this information >>>>> + * can be exported to userspace tools via >>>>> + * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 >>>>> + * then we're just getting a count and we can skip the >>>>> + * lookup stuff. >>>>> + */ >>>>> + ret = btrfs_check_shared(root, >>>>> + ino, disk_bytenr); >>>>> + if (ret < 0) >>>>> + goto error; >>>>> + if (ret) >>>>> + shared = 1; >>>>> + ret = 0; >>>>> + if (shared) { >>>>> + break; >>>>> + } >>>>> + } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) { >>>>> + extent_end = found_key.offset + >>>>> + btrfs_file_extent_inline_len(leaf, >>>>> + path->slots[0], fi); >>>>> + extent_end = ALIGN(extent_end, fs_info->sectorsize); >>>>> + path->slots[0]++; >>>>> + goto next_slot; >>>>> + } else { >>>>> + BUG_ON(1); >>>>> + } >>>>> + cur_offset = extent_end; >>>>> + if (cur_offset > end) >>>>> + break; >>>>> + } >>>>> + >>>>> + ret = 0; >>>>> +error: >>>>> + btrfs_free_path(path); >>>>> + return !ret ? shared : ret; >>>>> +} >>>>> + >>>>> int extent_fiemap(struct inode *inode, struct fiemap_extent_info >>>>> *fieinfo, >>>>> __u64 start, __u64 len, get_extent_t *get_extent) >>>>> { >>>>> @@ -4587,19 +4715,7 @@ int extent_fiemap(struct inode *inode, struct >>>>> fiemap_extent_info *fieinfo, >>>>> flags |= (FIEMAP_EXTENT_DELALLOC | >>>>> FIEMAP_EXTENT_UNKNOWN); >>>>> } else if (fieinfo->fi_extents_max) { >>>>> - u64 bytenr = em->block_start - >>>>> - (em->start - em->orig_start); >>>>> - >>>>> - /* >>>>> - * As btrfs supports shared space, this information >>>>> - * can be exported to userspace tools via >>>>> - * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 >>>>> - * then we're just getting a count and we can skip the >>>>> - * lookup stuff. >>>>> - */ >>>>> - ret = btrfs_check_shared(root, >>>>> - btrfs_ino(BTRFS_I(inode)), >>>>> - bytenr); >>>> >>>> Since we're going to use the whole extent to determine the SHARED flags, >>>> what about just passing the extent bytenr into btrfs_check_shared? >>>> >>>> In that case I think we could get correct shared flag without using >>>> another helper function. >>>> (IIRC it's em->block_start) >>> >>> Well, it's not em->block_start, but a little more complex. >>> (For compressed one it's em->block_start, but for plaintext one, it's >>> more complex) >>> >>> em->block_start = file_extent_disk_bytenr + >>> file_extent_file_extent_offset >>> >>> We need extra calculation to determine the real extent bytenr >>> (file_extent_disk_bytenr). >>> >>> IIRC the correct calculation would be: >>> file_extent_disk_bytenr = em->block_start - em->start + em->orig_start. >>> >>> (Who thought out such anti-human calculation for extent map?!) >>> >>> Thanks, >>> Qu >> >> dd if=/dev/zero bs=16K count=4 oflag=dsync of=file >> >> btrfs-debugfs -f file >> (276 0): ram 16384 disk 2171609088 disk_size 16384 >> (276 16384): ram 16384 disk 2171625472 disk_size 16384 >> (276 32768): ram 16384 disk 2171641856 disk_size 16384 >> (276 49152): ram 16384 disk 2171658240 disk_size 16384 >> file: file extents 4 disk size 65536 logical size 65536 ratio 1.00 >> >> xfs_io -c "fiemap -v" file >> file: >> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >> 0: [0..127]: 4241424..4241551 128 0x1 >> >> My point is that we have only one extent_map, >> but in fact it can correspond to many extents >> and each one has the potential to be cloned >> so we need to examine each one individually. > > Right, I missed this point. > > SHARED flag is determined after extent map merge, so here we can't rely > on em here. Shouldn't extent maps correspond to 1:1 disk-state. I.e. they are just the memory cache of the extent state. So if we merge them, shouldn't we also merge the on-disk extents as well ? > > So the current helper function looks valid, unless we have method to > access the original extent map. > > Thanks, > Qu > >> >> >>>> >>>> Thanks, >>>> Qu >>>> >>>>> + ret = extent_map_check_shared(inode, em->start, >>>>> extent_map_end(em) - 1); >>>>> if (ret < 0) >>>>> goto out_free; >>>>> if (ret) >>>>> -- >>>>> 1.9.1 >>>>> >>>>> -- >>>>> To unsubscribe from this list: send the line "unsubscribe >>>>> linux-btrfs" in >>>>> the body of a message to majordomo@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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2018年03月07日 19:27, Nikolay Borisov wrote: > > > On 7.03.2018 13:18, Qu Wenruo wrote: >> >> >> On 2018年03月07日 19:01, robbieko wrote: >>> Qu Wenruo 於 2018-03-07 18:42 寫到: >>>> On 2018年03月07日 18:33, Qu Wenruo wrote: >>>>> >>>>> >>>>> On 2018年03月07日 16:20, robbieko wrote: >>>>>> From: Robbie Ko <robbieko@synology.com> >>>>>> >>>>>> [BUG] >>>>>> Range clone can cause fiemap to return error result. >>>>>> Like: >>>>>> # mount /dev/vdb5 /mnt/btrfs >>>>>> # dd if=ev/zero bsK count=2 oflag=dsync of=/mnt/btrfs/file >>>>>> # xfs_io -c "fiemap -v" /mnt/btrfs/file >>>>>> /mnt/btrfs/file: >>>>>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>>>>> 0: [0..63]: 4241424..4241487 64 0x1 >>>>>> >>>>>> # cloner -s $((16*1024)) /mnt/btrfs/file /mnt/btrfs/file_clone >>>>>> # xfs_io -c "fiemap -v" /mnt/btrfs/file >>>>>> /mnt/btrfs/file: >>>>>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>>>>> 0: [0..63]: 4241424..4241487 64 0x1 >>>>>> If we clone second file extent, we will get error FLAGS, >>>>>> SHARED bit is not set. >>>>>> >>>>>> [REASON] >>>>>> Btrfs only checks if the first extent in extent map is shared, >>>>>> but extent may merge. >>>>>> >>>>>> [FIX] >>>>>> Here we will check each extent with extent map range, >>>>>> if one of them is shared, extent map is shared. >>>>>> >>>>>> [PATCH RESULT] >>>>>> # xfs_io -c "fiemap -v" /mnt/btrfs/file >>>>>> /mnt/btrfs/file: >>>>>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>>>>> 0: [0..63]: 4241424..4241487 64 0x2001 >>>>>> >>>>>> Signed-off-by: Robbie Ko <robbieko@synology.com> >>>>>> --- >>>>>> fs/btrfs/extent_io.c | 146 >>>>>> +++++++++++++++++++++++++++++++++++++++++++++------ >>>>>> 1 file changed, 131 insertions(+), 15 deletions(-) >>>>>> >>>>>> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c >>>>>> index 066b6df..5c6dca9 100644 >>>>>> --- a/fs/btrfs/extent_io.c >>>>>> +++ b/fs/btrfs/extent_io.c >>>>>> @@ -4394,8 +4394,8 @@ static int emit_fiemap_extent(struct >>>>>> fiemap_extent_info *fieinfo, >>>>>> */ >>>>>> if (cache->offset + cache->len =offset && >>>>>> cache->phys + cache->len =phys && >>>>>> - (cache->flags & ~FIEMAP_EXTENT_LAST) =>>>>> - (flags & ~FIEMAP_EXTENT_LAST)) { >>>>>> + (cache->flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED)) =>>>>> + (flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED))) { >>>>>> cache->len +=en; >>>>>> cache->flags |=lags; >>>>>> goto try_submit_last; >>>>>> @@ -4450,6 +4450,134 @@ static int emit_last_fiemap_cache(struct >>>>>> btrfs_fs_info *fs_info, >>>>>> return ret; >>>>>> } >>>>>> >>>>>> +/* >>>>>> + * Helper to check the file range is shared. >>>>>> + * >>>>>> + * Fiemap extent will be combined with many extents, so we need to >>>>>> examine >>>>>> + * each extent, and if shared, the results are shared. >>>>>> + * >>>>>> + * Return: 0 if file range is not shared, 1 if it is shared, < 0 on >>>>>> error. >>>>>> + */ >>>>>> +static int extent_map_check_shared(struct inode *inode, u64 start, >>>>>> u64 end) >>>>>> +{ >>>>>> + struct btrfs_fs_info *fs_info =trfs_sb(inode->i_sb); >>>>>> + struct btrfs_root *root =TRFS_I(inode)->root; >>>>>> + int ret =; >>>>>> + struct extent_buffer *leaf; >>>>>> + struct btrfs_path *path; >>>>>> + struct btrfs_file_extent_item *fi; >>>>>> + struct btrfs_key found_key; >>>>>> + int check_prev =; >>>>>> + int extent_type; >>>>>> + int shared =; >>>>>> + u64 cur_offset; >>>>>> + u64 extent_end; >>>>>> + u64 ino =trfs_ino(BTRFS_I(inode)); >>>>>> + u64 disk_bytenr; >>>>>> + >>>>>> + path =trfs_alloc_path(); >>>>>> + if (!path) { >>>>>> + return -ENOMEM; >>>>>> + } >>>>>> + >>>>>> + cur_offset =tart; >>>>>> + while (1) { >>>>>> + ret =trfs_lookup_file_extent(NULL, root, path, ino, >>>>>> + cur_offset, 0); >>>>>> + if (ret < 0) >>>>>> + goto error; >>>>>> + if (ret > 0 && path->slots[0] > 0 && check_prev) { >>>>>> + leaf =ath->nodes[0]; >>>>>> + btrfs_item_key_to_cpu(leaf, &found_key, >>>>>> + path->slots[0] - 1); >>>>>> + if (found_key.objectid =ino && >>>>>> + found_key.type =BTRFS_EXTENT_DATA_KEY) >>>>>> + path->slots[0]--; >>>>>> + } >>>>>> + check_prev =; >>>>>> +next_slot: >>>>>> + leaf =ath->nodes[0]; >>>>>> + if (path->slots[0] >=trfs_header_nritems(leaf)) { >>>>>> + ret =trfs_next_leaf(root, path); >>>>>> + if (ret < 0) >>>>>> + goto error; >>>>>> + if (ret > 0) >>>>>> + break; >>>>>> + leaf =ath->nodes[0]; >>>>>> + } >>>>>> + >>>>>> + disk_bytenr =; >>>>>> + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); >>>>>> + >>>>>> + if (found_key.objectid > ino) >>>>>> + break; >>>>>> + if (WARN_ON_ONCE(found_key.objectid < ino) || >>>>>> + found_key.type < BTRFS_EXTENT_DATA_KEY) { >>>>>> + path->slots[0]++; >>>>>> + goto next_slot; >>>>>> + } >>>>>> + if (found_key.type > BTRFS_EXTENT_DATA_KEY || >>>>>> + found_key.offset > end) >>>>>> + break; >>>>>> + >>>>>> + fi =trfs_item_ptr(leaf, path->slots[0], >>>>>> + struct btrfs_file_extent_item); >>>>>> + extent_type =trfs_file_extent_type(leaf, fi); >>>>>> + >>>>>> + if (extent_type =BTRFS_FILE_EXTENT_REG || >>>>>> + extent_type =BTRFS_FILE_EXTENT_PREALLOC) { >>>>>> + disk_bytenr =trfs_file_extent_disk_bytenr(leaf, fi); >>>>>> + extent_end =ound_key.offset + >>>>>> + btrfs_file_extent_num_bytes(leaf, fi); >>>>>> + if (extent_end <=tart) { >>>>>> + path->slots[0]++; >>>>>> + goto next_slot; >>>>>> + } >>>>>> + if (disk_bytenr =0) { >>>>>> + path->slots[0]++; >>>>>> + goto next_slot; >>>>>> + } >>>>>> + >>>>>> + btrfs_release_path(path); >>>>>> + >>>>>> + /* >>>>>> + * As btrfs supports shared space, this information >>>>>> + * can be exported to userspace tools via >>>>>> + * flag FIEMAP_EXTENT_SHARED. If fi_extents_max =0 >>>>>> + * then we're just getting a count and we can skip the >>>>>> + * lookup stuff. >>>>>> + */ >>>>>> + ret =trfs_check_shared(root, >>>>>> + ino, disk_bytenr); >>>>>> + if (ret < 0) >>>>>> + goto error; >>>>>> + if (ret) >>>>>> + shared =; >>>>>> + ret =; >>>>>> + if (shared) { >>>>>> + break; >>>>>> + } >>>>>> + } else if (extent_type =BTRFS_FILE_EXTENT_INLINE) { >>>>>> + extent_end =ound_key.offset + >>>>>> + btrfs_file_extent_inline_len(leaf, >>>>>> + path->slots[0], fi); >>>>>> + extent_end =LIGN(extent_end, fs_info->sectorsize); >>>>>> + path->slots[0]++; >>>>>> + goto next_slot; >>>>>> + } else { >>>>>> + BUG_ON(1); >>>>>> + } >>>>>> + cur_offset =xtent_end; >>>>>> + if (cur_offset > end) >>>>>> + break; >>>>>> + } >>>>>> + >>>>>> + ret =; >>>>>> +error: >>>>>> + btrfs_free_path(path); >>>>>> + return !ret ? shared : ret; >>>>>> +} >>>>>> + >>>>>> int extent_fiemap(struct inode *inode, struct fiemap_extent_info >>>>>> *fieinfo, >>>>>> __u64 start, __u64 len, get_extent_t *get_extent) >>>>>> { >>>>>> @@ -4587,19 +4715,7 @@ int extent_fiemap(struct inode *inode, struct >>>>>> fiemap_extent_info *fieinfo, >>>>>> flags |=FIEMAP_EXTENT_DELALLOC | >>>>>> FIEMAP_EXTENT_UNKNOWN); >>>>>> } else if (fieinfo->fi_extents_max) { >>>>>> - u64 bytenr =m->block_start - >>>>>> - (em->start - em->orig_start); >>>>>> - >>>>>> - /* >>>>>> - * As btrfs supports shared space, this information >>>>>> - * can be exported to userspace tools via >>>>>> - * flag FIEMAP_EXTENT_SHARED. If fi_extents_max =0 >>>>>> - * then we're just getting a count and we can skip the >>>>>> - * lookup stuff. >>>>>> - */ >>>>>> - ret =trfs_check_shared(root, >>>>>> - btrfs_ino(BTRFS_I(inode)), >>>>>> - bytenr); >>>>> >>>>> Since we're going to use the whole extent to determine the SHARED flags, >>>>> what about just passing the extent bytenr into btrfs_check_shared? >>>>> >>>>> In that case I think we could get correct shared flag without using >>>>> another helper function. >>>>> (IIRC it's em->block_start) >>>> >>>> Well, it's not em->block_start, but a little more complex. >>>> (For compressed one it's em->block_start, but for plaintext one, it's >>>> more complex) >>>> >>>> em->block_start =ile_extent_disk_bytenr + >>>> file_extent_file_extent_offset >>>> >>>> We need extra calculation to determine the real extent bytenr >>>> (file_extent_disk_bytenr). >>>> >>>> IIRC the correct calculation would be: >>>> file_extent_disk_bytenr =m->block_start - em->start + em->orig_start. >>>> >>>> (Who thought out such anti-human calculation for extent map?!) >>>> >>>> Thanks, >>>> Qu >>> >>> dd if=ev/zero bsK count=4 oflag=dsync of=file >>> >>> btrfs-debugfs -f file >>> (276 0): ram 16384 disk 2171609088 disk_size 16384 >>> (276 16384): ram 16384 disk 2171625472 disk_size 16384 >>> (276 32768): ram 16384 disk 2171641856 disk_size 16384 >>> (276 49152): ram 16384 disk 2171658240 disk_size 16384 >>> file: file extents 4 disk size 65536 logical size 65536 ratio 1.00 >>> >>> xfs_io -c "fiemap -v" file >>> file: >>> EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS >>> 0: [0..127]: 4241424..4241551 128 0x1 >>> >>> My point is that we have only one extent_map, >>> but in fact it can correspond to many extents >>> and each one has the potential to be cloned >>> so we need to examine each one individually. >> >> Right, I missed this point. >> >> SHARED flag is determined after extent map merge, so here we can't rely >> on em here. > > Shouldn't extent maps correspond to 1:1 disk-state. I.e. they are just > the memory cache of the extent state. So if we merge them, shouldn't we > also merge the on-disk extents as well ? Not 1:1. In memory one is merged maybe to save memory. But on-disk file extents has size limit. For compressed one it's 128K and 128M for uncompressed one. And for on-disk file extent size limit, it could be reduce extent booking space waste and other reasons. Thanks, Qu > >> >> So the current helper function looks valid, unless we have method to >> access the original extent map. >> >> Thanks, >> Qu >> >>> >>> >>>>> >>>>> Thanks, >>>>> Qu >>>>> >>>>>> + ret =xtent_map_check_shared(inode, em->start, >>>>>> extent_map_end(em) - 1); >>>>>> if (ret < 0) >>>>>> goto out_free; >>>>>> if (ret) >>>>>> -- >>>>>> 1.9.1 >>>>>> >>>>>> -- >>>>>> To unsubscribe from this list: send the line "unsubscribe >>>>>> linux-btrfs" in >>>>>> the body of a message to majordomo@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 majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
On 7.03.2018 14:14, Qu Wenruo wrote: > > <snip> >>> >>> SHARED flag is determined after extent map merge, so here we can't rely >>> on em here. >> >> Shouldn't extent maps correspond to 1:1 disk-state. I.e. they are just >> the memory cache of the extent state. So if we merge them, shouldn't we >> also merge the on-disk extents as well ? > > Not 1:1. > > In memory one is merged maybe to save memory. > > But on-disk file extents has size limit. > For compressed one it's 128K and 128M for uncompressed one. Fair enough, however 4 extents, 16k each should warrant merging on-disk as well, no ? <snip> -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2018年03月07日 20:17, Nikolay Borisov wrote: > > > On 7.03.2018 14:14, Qu Wenruo wrote: >> >> > > <snip> > >>>> >>>> SHARED flag is determined after extent map merge, so here we can't rely >>>> on em here. >>> >>> Shouldn't extent maps correspond to 1:1 disk-state. I.e. they are just >>> the memory cache of the extent state. So if we merge them, shouldn't we >>> also merge the on-disk extents as well ? >> >> Not 1:1. >> >> In memory one is merged maybe to save memory. >> >> But on-disk file extents has size limit. >> For compressed one it's 128K and 128M for uncompressed one. > > Fair enough, however 4 extents, 16k each should warrant merging on-disk > as well, no ? dd oflag=dsync That ensures we won't merge on-disk extents. Thanks, Qu > > <snip> > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 066b6df..5c6dca9 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -4394,8 +4394,8 @@ static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo, */ if (cache->offset + cache->len == offset && cache->phys + cache->len == phys && - (cache->flags & ~FIEMAP_EXTENT_LAST) == - (flags & ~FIEMAP_EXTENT_LAST)) { + (cache->flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED)) == + (flags & ~(FIEMAP_EXTENT_LAST|FIEMAP_EXTENT_SHARED))) { cache->len += len; cache->flags |= flags; goto try_submit_last; @@ -4450,6 +4450,134 @@ static int emit_last_fiemap_cache(struct btrfs_fs_info *fs_info, return ret; } +/* + * Helper to check the file range is shared. + * + * Fiemap extent will be combined with many extents, so we need to examine + * each extent, and if shared, the results are shared. + * + * Return: 0 if file range is not shared, 1 if it is shared, < 0 on error. + */ +static int extent_map_check_shared(struct inode *inode, u64 start, u64 end) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + struct btrfs_root *root = BTRFS_I(inode)->root; + int ret = 0; + struct extent_buffer *leaf; + struct btrfs_path *path; + struct btrfs_file_extent_item *fi; + struct btrfs_key found_key; + int check_prev = 1; + int extent_type; + int shared = 0; + u64 cur_offset; + u64 extent_end; + u64 ino = btrfs_ino(BTRFS_I(inode)); + u64 disk_bytenr; + + path = btrfs_alloc_path(); + if (!path) { + return -ENOMEM; + } + + cur_offset = start; + while (1) { + ret = btrfs_lookup_file_extent(NULL, root, path, ino, + cur_offset, 0); + if (ret < 0) + goto error; + if (ret > 0 && path->slots[0] > 0 && check_prev) { + leaf = path->nodes[0]; + btrfs_item_key_to_cpu(leaf, &found_key, + path->slots[0] - 1); + if (found_key.objectid == ino && + found_key.type == BTRFS_EXTENT_DATA_KEY) + path->slots[0]--; + } + check_prev = 0; +next_slot: + leaf = path->nodes[0]; + if (path->slots[0] >= btrfs_header_nritems(leaf)) { + ret = btrfs_next_leaf(root, path); + if (ret < 0) + goto error; + if (ret > 0) + break; + leaf = path->nodes[0]; + } + + disk_bytenr = 0; + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); + + if (found_key.objectid > ino) + break; + if (WARN_ON_ONCE(found_key.objectid < ino) || + found_key.type < BTRFS_EXTENT_DATA_KEY) { + path->slots[0]++; + goto next_slot; + } + if (found_key.type > BTRFS_EXTENT_DATA_KEY || + found_key.offset > end) + break; + + fi = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); + extent_type = btrfs_file_extent_type(leaf, fi); + + if (extent_type == BTRFS_FILE_EXTENT_REG || + extent_type == BTRFS_FILE_EXTENT_PREALLOC) { + disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi); + extent_end = found_key.offset + + btrfs_file_extent_num_bytes(leaf, fi); + if (extent_end <= start) { + path->slots[0]++; + goto next_slot; + } + if (disk_bytenr == 0) { + path->slots[0]++; + goto next_slot; + } + + btrfs_release_path(path); + + /* + * As btrfs supports shared space, this information + * can be exported to userspace tools via + * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 + * then we're just getting a count and we can skip the + * lookup stuff. + */ + ret = btrfs_check_shared(root, + ino, disk_bytenr); + if (ret < 0) + goto error; + if (ret) + shared = 1; + ret = 0; + if (shared) { + break; + } + } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) { + extent_end = found_key.offset + + btrfs_file_extent_inline_len(leaf, + path->slots[0], fi); + extent_end = ALIGN(extent_end, fs_info->sectorsize); + path->slots[0]++; + goto next_slot; + } else { + BUG_ON(1); + } + cur_offset = extent_end; + if (cur_offset > end) + break; + } + + ret = 0; +error: + btrfs_free_path(path); + return !ret ? shared : ret; +} + int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, __u64 start, __u64 len, get_extent_t *get_extent) { @@ -4587,19 +4715,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, flags |= (FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN); } else if (fieinfo->fi_extents_max) { - u64 bytenr = em->block_start - - (em->start - em->orig_start); - - /* - * As btrfs supports shared space, this information - * can be exported to userspace tools via - * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 - * then we're just getting a count and we can skip the - * lookup stuff. - */ - ret = btrfs_check_shared(root, - btrfs_ino(BTRFS_I(inode)), - bytenr); + ret = extent_map_check_shared(inode, em->start, extent_map_end(em) - 1); if (ret < 0) goto out_free; if (ret)