| Message ID | 20210608025927.119169-7-wqu@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: defrag: rework to support sector perfect defrag | expand |
On 2021/6/8 上午10:59, Qu Wenruo wrote: > A new helper, defrag_one_range(), is introduced to defrag one range. > > This function will mostly prepare the needed pages and extent status for > defrag_one_locked_target(). > > As we can only have a consistent view of extent map with page and > extent bits locked, we need to re-check the range passed in to get a > real target list for defrag_one_locked_target(). > > Since defrag_collect_targets() will call defrag_lookup_extent() and lock > extent range, we also need to teach those two functions to skip extent > lock. > Thus new parameter, @locked, is introruced to skip extent lock if the > caller has already locked the range. > > Signed-off-by: Qu Wenruo <wqu@suse.com> > --- > fs/btrfs/ioctl.c | 94 ++++++++++++++++++++++++++++++++++++++++++++---- > 1 file changed, 87 insertions(+), 7 deletions(-) > > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c > index 42e757dfdd7b..8259ad102469 100644 > --- a/fs/btrfs/ioctl.c > +++ b/fs/btrfs/ioctl.c > @@ -1033,7 +1033,8 @@ static int find_new_extents(struct btrfs_root *root, > return -ENOENT; > } > > -static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start) > +static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start, > + bool locked) > { > struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree; > struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; > @@ -1053,10 +1054,12 @@ static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start) > u64 end = start + sectorsize - 1; > > /* get the big lock and read metadata off disk */ > - lock_extent_bits(io_tree, start, end, &cached); > + if (!locked) > + lock_extent_bits(io_tree, start, end, &cached); > em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, > sectorsize); > - unlock_extent_cached(io_tree, start, end, &cached); > + if (!locked) > + unlock_extent_cached(io_tree, start, end, &cached); > > if (IS_ERR(em)) > return NULL; > @@ -1074,7 +1077,7 @@ static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em) > if (em->start + em->len >= i_size_read(inode)) > return false; > > - next = defrag_lookup_extent(inode, em->start + em->len); > + next = defrag_lookup_extent(inode, em->start + em->len, false); Here the fixed false parameter is causing another hang. As defrag_check_next_extent() can be called inside defrag_collect_targets(), which can be called with extent locked. Will fix it in next update. Thanks, Qu > if (!next || next->block_start >= EXTENT_MAP_LAST_BYTE) > ret = false; > else if ((em->block_start + em->block_len == next->block_start) && > @@ -1103,7 +1106,7 @@ static int should_defrag_range(struct inode *inode, u64 start, u32 thresh, > > *skip = 0; > > - em = defrag_lookup_extent(inode, start); > + em = defrag_lookup_extent(inode, start, false); > if (!em) > return 0; > > @@ -1390,12 +1393,13 @@ struct defrag_target_range { > * @do_compress: Whether the defrag is doing compression > * If true, @extent_thresh will be ignored and all regular > * file extents meeting @newer_than will be targets. > + * @locked: If the range has already hold extent lock > * @target_list: The list of targets file extents > */ > static int defrag_collect_targets(struct btrfs_inode *inode, > u64 start, u64 len, u32 extent_thresh, > u64 newer_than, bool do_compress, > - struct list_head *target_list) > + bool locked, struct list_head *target_list) > { > u64 cur = start; > int ret = 0; > @@ -1406,7 +1410,7 @@ static int defrag_collect_targets(struct btrfs_inode *inode, > bool next_mergeable = true; > u64 range_len; > > - em = defrag_lookup_extent(&inode->vfs_inode, cur); > + em = defrag_lookup_extent(&inode->vfs_inode, cur, locked); > if (!em) > break; > > @@ -1548,6 +1552,82 @@ static int defrag_one_locked_target(struct btrfs_inode *inode, > return ret; > } > > +static int defrag_one_range(struct btrfs_inode *inode, > + u64 start, u32 len, > + u32 extent_thresh, u64 newer_than, > + bool do_compress) > +{ > + struct extent_state *cached_state = NULL; > + struct defrag_target_range *entry; > + struct defrag_target_range *tmp; > + LIST_HEAD(target_list); > + struct page **pages; > + const u32 sectorsize = inode->root->fs_info->sectorsize; > + unsigned long last_index = (start + len - 1) >> PAGE_SHIFT; > + unsigned long start_index = start >> PAGE_SHIFT; > + unsigned int nr_pages = last_index - start_index + 1; > + int ret = 0; > + int i; > + > + ASSERT(nr_pages <= CLUSTER_SIZE / PAGE_SIZE); > + ASSERT(IS_ALIGNED(start, sectorsize) && IS_ALIGNED(len, sectorsize)); > + > + pages = kzalloc(sizeof(struct page *) * nr_pages, GFP_NOFS); > + if (!pages) > + return -ENOMEM; > + > + /* Prepare all pages */ > + for (i = 0; i < nr_pages; i++) { > + pages[i] = defrag_prepare_one_page(inode, start_index + i); > + if (IS_ERR(pages[i])) { > + ret = PTR_ERR(pages[i]); > + pages[i] = NULL; > + goto free_pages; > + } > + } > + /* Also lock the pages range */ > + lock_extent_bits(&inode->io_tree, start_index << PAGE_SHIFT, > + (last_index << PAGE_SHIFT) + PAGE_SIZE - 1, > + &cached_state); > + /* > + * Now we have a consistent view about the extent map, re-check > + * which range really need to be defraged. > + * > + * And this time we have extent locked already, pass @locked = true > + * so that we won't re-lock the extent range and cause deadlock. > + */ > + ret = defrag_collect_targets(inode, start, len, extent_thresh, > + newer_than, do_compress, true, > + &target_list); > + if (ret < 0) > + goto unlock_extent; > + > + list_for_each_entry(entry, &target_list, list) { > + ret = defrag_one_locked_target(inode, entry, pages, nr_pages, > + &cached_state); > + if (ret < 0) > + break; > + } > + > + list_for_each_entry_safe(entry, tmp, &target_list, list) { > + list_del_init(&entry->list); > + kfree(entry); > + } > +unlock_extent: > + unlock_extent_cached(&inode->io_tree, start_index << PAGE_SHIFT, > + (last_index << PAGE_SHIFT) + PAGE_SIZE - 1, > + &cached_state); > +free_pages: > + for (i = 0; i < nr_pages; i++) { > + if (pages[i]) { > + unlock_page(pages[i]); > + put_page(pages[i]); > + } > + } > + kfree(pages); > + return ret; > +} > + > /* > * Btrfs entrace for defrag. > * >
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 42e757dfdd7b..8259ad102469 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1033,7 +1033,8 @@ static int find_new_extents(struct btrfs_root *root, return -ENOENT; } -static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start) +static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start, + bool locked) { struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree; struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; @@ -1053,10 +1054,12 @@ static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start) u64 end = start + sectorsize - 1; /* get the big lock and read metadata off disk */ - lock_extent_bits(io_tree, start, end, &cached); + if (!locked) + lock_extent_bits(io_tree, start, end, &cached); em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, sectorsize); - unlock_extent_cached(io_tree, start, end, &cached); + if (!locked) + unlock_extent_cached(io_tree, start, end, &cached); if (IS_ERR(em)) return NULL; @@ -1074,7 +1077,7 @@ static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em) if (em->start + em->len >= i_size_read(inode)) return false; - next = defrag_lookup_extent(inode, em->start + em->len); + next = defrag_lookup_extent(inode, em->start + em->len, false); if (!next || next->block_start >= EXTENT_MAP_LAST_BYTE) ret = false; else if ((em->block_start + em->block_len == next->block_start) && @@ -1103,7 +1106,7 @@ static int should_defrag_range(struct inode *inode, u64 start, u32 thresh, *skip = 0; - em = defrag_lookup_extent(inode, start); + em = defrag_lookup_extent(inode, start, false); if (!em) return 0; @@ -1390,12 +1393,13 @@ struct defrag_target_range { * @do_compress: Whether the defrag is doing compression * If true, @extent_thresh will be ignored and all regular * file extents meeting @newer_than will be targets. + * @locked: If the range has already hold extent lock * @target_list: The list of targets file extents */ static int defrag_collect_targets(struct btrfs_inode *inode, u64 start, u64 len, u32 extent_thresh, u64 newer_than, bool do_compress, - struct list_head *target_list) + bool locked, struct list_head *target_list) { u64 cur = start; int ret = 0; @@ -1406,7 +1410,7 @@ static int defrag_collect_targets(struct btrfs_inode *inode, bool next_mergeable = true; u64 range_len; - em = defrag_lookup_extent(&inode->vfs_inode, cur); + em = defrag_lookup_extent(&inode->vfs_inode, cur, locked); if (!em) break; @@ -1548,6 +1552,82 @@ static int defrag_one_locked_target(struct btrfs_inode *inode, return ret; } +static int defrag_one_range(struct btrfs_inode *inode, + u64 start, u32 len, + u32 extent_thresh, u64 newer_than, + bool do_compress) +{ + struct extent_state *cached_state = NULL; + struct defrag_target_range *entry; + struct defrag_target_range *tmp; + LIST_HEAD(target_list); + struct page **pages; + const u32 sectorsize = inode->root->fs_info->sectorsize; + unsigned long last_index = (start + len - 1) >> PAGE_SHIFT; + unsigned long start_index = start >> PAGE_SHIFT; + unsigned int nr_pages = last_index - start_index + 1; + int ret = 0; + int i; + + ASSERT(nr_pages <= CLUSTER_SIZE / PAGE_SIZE); + ASSERT(IS_ALIGNED(start, sectorsize) && IS_ALIGNED(len, sectorsize)); + + pages = kzalloc(sizeof(struct page *) * nr_pages, GFP_NOFS); + if (!pages) + return -ENOMEM; + + /* Prepare all pages */ + for (i = 0; i < nr_pages; i++) { + pages[i] = defrag_prepare_one_page(inode, start_index + i); + if (IS_ERR(pages[i])) { + ret = PTR_ERR(pages[i]); + pages[i] = NULL; + goto free_pages; + } + } + /* Also lock the pages range */ + lock_extent_bits(&inode->io_tree, start_index << PAGE_SHIFT, + (last_index << PAGE_SHIFT) + PAGE_SIZE - 1, + &cached_state); + /* + * Now we have a consistent view about the extent map, re-check + * which range really need to be defraged. + * + * And this time we have extent locked already, pass @locked = true + * so that we won't re-lock the extent range and cause deadlock. + */ + ret = defrag_collect_targets(inode, start, len, extent_thresh, + newer_than, do_compress, true, + &target_list); + if (ret < 0) + goto unlock_extent; + + list_for_each_entry(entry, &target_list, list) { + ret = defrag_one_locked_target(inode, entry, pages, nr_pages, + &cached_state); + if (ret < 0) + break; + } + + list_for_each_entry_safe(entry, tmp, &target_list, list) { + list_del_init(&entry->list); + kfree(entry); + } +unlock_extent: + unlock_extent_cached(&inode->io_tree, start_index << PAGE_SHIFT, + (last_index << PAGE_SHIFT) + PAGE_SIZE - 1, + &cached_state); +free_pages: + for (i = 0; i < nr_pages; i++) { + if (pages[i]) { + unlock_page(pages[i]); + put_page(pages[i]); + } + } + kfree(pages); + return ret; +} + /* * Btrfs entrace for defrag. *
A new helper, defrag_one_range(), is introduced to defrag one range. This function will mostly prepare the needed pages and extent status for defrag_one_locked_target(). As we can only have a consistent view of extent map with page and extent bits locked, we need to re-check the range passed in to get a real target list for defrag_one_locked_target(). Since defrag_collect_targets() will call defrag_lookup_extent() and lock extent range, we also need to teach those two functions to skip extent lock. Thus new parameter, @locked, is introruced to skip extent lock if the caller has already locked the range. Signed-off-by: Qu Wenruo <wqu@suse.com> --- fs/btrfs/ioctl.c | 94 ++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 87 insertions(+), 7 deletions(-)