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btrfs: move the file defrag code into defrag.c 

This is the other big portion of defrag code that has existed in
ioctl.c.  Move it to its new home in defrag.c.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2022-10-26 15:08:24 -04:00 committed by David Sterba
parent 6e3df18ba7
commit a6a01ca61f
2 changed files with 903 additions and 902 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

903
fs/btrfs/defrag.c
View File

@ -10,6 +10,9 @@
#include "transaction.h"
#include "locking.h"
#include "accessors.h"
#include "messages.h"
#include "delalloc-space.h"
#include "subpage.h"
static struct kmem_cache *btrfs_inode_defrag_cachep;
@ -452,6 +455,906 @@ done:
return ret;
}
/*
* Defrag specific helper to get an extent map.
*
* Differences between this and btrfs_get_extent() are:
*
* - No extent_map will be added to inode->extent_tree
* To reduce memory usage in the long run.
*
* - Extra optimization to skip file extents older than @newer_than
* By using btrfs_search_forward() we can skip entire file ranges that
* have extents created in past transactions, because btrfs_search_forward()
* will not visit leaves and nodes with a generation smaller than given
* minimal generation threshold (@newer_than).
*
* Return valid em if we find a file extent matching the requirement.
* Return NULL if we can not find a file extent matching the requirement.
*
* Return ERR_PTR() for error.
*/
static struct extent_map *defrag_get_extent(struct btrfs_inode *inode,
u64 start, u64 newer_than)
{
struct btrfs_root *root = inode->root;
struct btrfs_file_extent_item *fi;
struct btrfs_path path = { 0 };
struct extent_map *em;
struct btrfs_key key;
u64 ino = btrfs_ino(inode);
int ret;
em = alloc_extent_map();
if (!em) {
ret = -ENOMEM;
goto err;
}
key.objectid = ino;
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = start;
if (newer_than) {
ret = btrfs_search_forward(root, &key, &path, newer_than);
if (ret < 0)
goto err;
/* Can't find anything newer */
if (ret > 0)
goto not_found;
} else {
ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
if (ret < 0)
goto err;
}
if (path.slots[0] >= btrfs_header_nritems(path.nodes[0])) {
/*
* If btrfs_search_slot() makes path to point beyond nritems,
* we should not have an empty leaf, as this inode must at
* least have its INODE_ITEM.
*/
ASSERT(btrfs_header_nritems(path.nodes[0]));
path.slots[0] = btrfs_header_nritems(path.nodes[0]) - 1;
}
btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
/* Perfect match, no need to go one slot back */
if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY &&
key.offset == start)
goto iterate;
/* We didn't find a perfect match, needs to go one slot back */
if (path.slots[0] > 0) {
btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY)
path.slots[0]--;
}
iterate:
/* Iterate through the path to find a file extent covering @start */
while (true) {
u64 extent_end;
if (path.slots[0] >= btrfs_header_nritems(path.nodes[0]))
goto next;
btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
/*
* We may go one slot back to INODE_REF/XATTR item, then
* need to go forward until we reach an EXTENT_DATA.
* But we should still has the correct ino as key.objectid.
*/
if (WARN_ON(key.objectid < ino) || key.type < BTRFS_EXTENT_DATA_KEY)
goto next;
/* It's beyond our target range, definitely not extent found */
if (key.objectid > ino || key.type > BTRFS_EXTENT_DATA_KEY)
goto not_found;
/*
* | |<- File extent ->|
* \- start
*
* This means there is a hole between start and key.offset.
*/
if (key.offset > start) {
em->start = start;
em->orig_start = start;
em->block_start = EXTENT_MAP_HOLE;
em->len = key.offset - start;
break;
}
fi = btrfs_item_ptr(path.nodes[0], path.slots[0],
struct btrfs_file_extent_item);
extent_end = btrfs_file_extent_end(&path);
/*
* |<- file extent ->| |
* \- start
*
* We haven't reached start, search next slot.
*/
if (extent_end <= start)
goto next;
/* Now this extent covers @start, convert it to em */
btrfs_extent_item_to_extent_map(inode, &path, fi, false, em);
break;
next:
ret = btrfs_next_item(root, &path);
if (ret < 0)
goto err;
if (ret > 0)
goto not_found;
}
btrfs_release_path(&path);
return em;
not_found:
btrfs_release_path(&path);
free_extent_map(em);
return NULL;
err:
btrfs_release_path(&path);
free_extent_map(em);
return ERR_PTR(ret);
}
static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start,
u64 newer_than, bool locked)
{
struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
struct extent_map *em;
const u32 sectorsize = BTRFS_I(inode)->root->fs_info->sectorsize;
/*
* Hopefully we have this extent in the tree already, try without the
* full extent lock.
*/
read_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, start, sectorsize);
read_unlock(&em_tree->lock);
/*
* We can get a merged extent, in that case, we need to re-search
* tree to get the original em for defrag.
*
* If @newer_than is 0 or em::generation < newer_than, we can trust
* this em, as either we don't care about the generation, or the
* merged extent map will be rejected anyway.
*/
if (em && test_bit(EXTENT_FLAG_MERGED, &em->flags) &&
newer_than && em->generation >= newer_than) {
free_extent_map(em);
em = NULL;
}
if (!em) {
struct extent_state *cached = NULL;
u64 end = start + sectorsize - 1;
/* Get the big lock and read metadata off disk. */
if (!locked)
lock_extent(io_tree, start, end, &cached);
em = defrag_get_extent(BTRFS_I(inode), start, newer_than);
if (!locked)
unlock_extent(io_tree, start, end, &cached);
if (IS_ERR(em))
return NULL;
}
return em;
}
static u32 get_extent_max_capacity(const struct btrfs_fs_info *fs_info,
const struct extent_map *em)
{
if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
return BTRFS_MAX_COMPRESSED;
return fs_info->max_extent_size;
}
static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em,
u32 extent_thresh, u64 newer_than, bool locked)
{
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
struct extent_map *next;
bool ret = false;
/* This is the last extent */
if (em->start + em->len >= i_size_read(inode))
return false;
/*
* Here we need to pass @newer_then when checking the next extent, or
* we will hit a case we mark current extent for defrag, but the next
* one will not be a target.
* This will just cause extra IO without really reducing the fragments.
*/
next = defrag_lookup_extent(inode, em->start + em->len, newer_than, locked);
/* No more em or hole */
if (!next || next->block_start >= EXTENT_MAP_LAST_BYTE)
goto out;
if (test_bit(EXTENT_FLAG_PREALLOC, &next->flags))
goto out;
/*
* If the next extent is at its max capacity, defragging current extent
* makes no sense, as the total number of extents won't change.
*/
if (next->len >= get_extent_max_capacity(fs_info, em))
goto out;
/* Skip older extent */
if (next->generation < newer_than)
goto out;
/* Also check extent size */
if (next->len >= extent_thresh)
goto out;
ret = true;
out:
free_extent_map(next);
return ret;
}
/*
* Prepare one page to be defragged.
*
* This will ensure:
*
* - Returned page is locked and has been set up properly.
* - No ordered extent exists in the page.
* - The page is uptodate.
*
* NOTE: Caller should also wait for page writeback after the cluster is
* prepared, here we don't do writeback wait for each page.
*/
static struct page *defrag_prepare_one_page(struct btrfs_inode *inode, pgoff_t index)
{
struct address_space *mapping = inode->vfs_inode.i_mapping;
gfp_t mask = btrfs_alloc_write_mask(mapping);
u64 page_start = (u64)index << PAGE_SHIFT;
u64 page_end = page_start + PAGE_SIZE - 1;
struct extent_state *cached_state = NULL;
struct page *page;
int ret;
again:
page = find_or_create_page(mapping, index, mask);
if (!page)
return ERR_PTR(-ENOMEM);
/*
* Since we can defragment files opened read-only, we can encounter
* transparent huge pages here (see CONFIG_READ_ONLY_THP_FOR_FS). We
* can't do I/O using huge pages yet, so return an error for now.
* Filesystem transparent huge pages are typically only used for
* executables that explicitly enable them, so this isn't very
* restrictive.
*/
if (PageCompound(page)) {
unlock_page(page);
put_page(page);
return ERR_PTR(-ETXTBSY);
}
ret = set_page_extent_mapped(page);
if (ret < 0) {
unlock_page(page);
put_page(page);
return ERR_PTR(ret);
}
/* Wait for any existing ordered extent in the range */
while (1) {
struct btrfs_ordered_extent *ordered;
lock_extent(&inode->io_tree, page_start, page_end, &cached_state);
ordered = btrfs_lookup_ordered_range(inode, page_start, PAGE_SIZE);
unlock_extent(&inode->io_tree, page_start, page_end,
&cached_state);
if (!ordered)
break;
unlock_page(page);
btrfs_start_ordered_extent(ordered, 1);
btrfs_put_ordered_extent(ordered);
lock_page(page);
/*
* We unlocked the page above, so we need check if it was
* released or not.
*/
if (page->mapping != mapping || !PagePrivate(page)) {
unlock_page(page);
put_page(page);
goto again;
}
}
/*
* Now the page range has no ordered extent any more. Read the page to
* make it uptodate.
*/
if (!PageUptodate(page)) {
btrfs_read_folio(NULL, page_folio(page));
lock_page(page);
if (page->mapping != mapping || !PagePrivate(page)) {
unlock_page(page);
put_page(page);
goto again;
}
if (!PageUptodate(page)) {
unlock_page(page);
put_page(page);
return ERR_PTR(-EIO);
}
}
return page;
}
struct defrag_target_range {
struct list_head list;
u64 start;
u64 len;
};
/*
* Collect all valid target extents.
*
* @start: file offset to lookup
* @len: length to lookup
* @extent_thresh: file extent size threshold, any extent size >= this value
* will be ignored
* @newer_than: only defrag extents newer than this value
* @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 held extent lock
* @target_list: 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,
bool locked, struct list_head *target_list,
u64 *last_scanned_ret)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
bool last_is_target = false;
u64 cur = start;
int ret = 0;
while (cur < start + len) {
struct extent_map *em;
struct defrag_target_range *new;
bool next_mergeable = true;
u64 range_len;
last_is_target = false;
em = defrag_lookup_extent(&inode->vfs_inode, cur, newer_than, locked);
if (!em)
break;
/*
* If the file extent is an inlined one, we may still want to
* defrag it (fallthrough) if it will cause a regular extent.
* This is for users who want to convert inline extents to
* regular ones through max_inline= mount option.
*/
if (em->block_start == EXTENT_MAP_INLINE &&
em->len <= inode->root->fs_info->max_inline)
goto next;
/* Skip hole/delalloc/preallocated extents */
if (em->block_start == EXTENT_MAP_HOLE ||
em->block_start == EXTENT_MAP_DELALLOC ||
test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
goto next;
/* Skip older extent */
if (em->generation < newer_than)
goto next;
/* This em is under writeback, no need to defrag */
if (em->generation == (u64)-1)
goto next;
/*
* Our start offset might be in the middle of an existing extent
* map, so take that into account.
*/
range_len = em->len - (cur - em->start);
/*
* If this range of the extent map is already flagged for delalloc,
* skip it, because:
*
* 1) We could deadlock later, when trying to reserve space for
* delalloc, because in case we can't immediately reserve space
* the flusher can start delalloc and wait for the respective
* ordered extents to complete. The deadlock would happen
* because we do the space reservation while holding the range
* locked, and starting writeback, or finishing an ordered
* extent, requires locking the range;
*
* 2) If there's delalloc there, it means there's dirty pages for
* which writeback has not started yet (we clean the delalloc
* flag when starting writeback and after creating an ordered
* extent). If we mark pages in an adjacent range for defrag,
* then we will have a larger contiguous range for delalloc,
* very likely resulting in a larger extent after writeback is
* triggered (except in a case of free space fragmentation).
*/
if (test_range_bit(&inode->io_tree, cur, cur + range_len - 1,
EXTENT_DELALLOC, 0, NULL))
goto next;
/*
* For do_compress case, we want to compress all valid file
* extents, thus no @extent_thresh or mergeable check.
*/
if (do_compress)
goto add;
/* Skip too large extent */
if (range_len >= extent_thresh)
goto next;
/*
* Skip extents already at its max capacity, this is mostly for
* compressed extents, which max cap is only 128K.
*/
if (em->len >= get_extent_max_capacity(fs_info, em))
goto next;
/*
* Normally there are no more extents after an inline one, thus
* @next_mergeable will normally be false and not defragged.
* So if an inline extent passed all above checks, just add it
* for defrag, and be converted to regular extents.
*/
if (em->block_start == EXTENT_MAP_INLINE)
goto add;
next_mergeable = defrag_check_next_extent(&inode->vfs_inode, em,
extent_thresh, newer_than, locked);
if (!next_mergeable) {
struct defrag_target_range *last;
/* Empty target list, no way to merge with last entry */
if (list_empty(target_list))
goto next;
last = list_entry(target_list->prev,
struct defrag_target_range, list);
/* Not mergeable with last entry */
if (last->start + last->len != cur)
goto next;
/* Mergeable, fall through to add it to @target_list. */
}
add:
last_is_target = true;
range_len = min(extent_map_end(em), start + len) - cur;
/*
* This one is a good target, check if it can be merged into
* last range of the target list.
*/
if (!list_empty(target_list)) {
struct defrag_target_range *last;
last = list_entry(target_list->prev,
struct defrag_target_range, list);
ASSERT(last->start + last->len <= cur);
if (last->start + last->len == cur) {
/* Mergeable, enlarge the last entry */
last->len += range_len;
goto next;
}
/* Fall through to allocate a new entry */
}
/* Allocate new defrag_target_range */
new = kmalloc(sizeof(*new), GFP_NOFS);
if (!new) {
free_extent_map(em);
ret = -ENOMEM;
break;
}
new->start = cur;
new->len = range_len;
list_add_tail(&new->list, target_list);
next:
cur = extent_map_end(em);
free_extent_map(em);
}
if (ret < 0) {
struct defrag_target_range *entry;
struct defrag_target_range *tmp;
list_for_each_entry_safe(entry, tmp, target_list, list) {
list_del_init(&entry->list);
kfree(entry);
}
}
if (!ret && last_scanned_ret) {
/*
* If the last extent is not a target, the caller can skip to
* the end of that extent.
* Otherwise, we can only go the end of the specified range.
*/
if (!last_is_target)
*last_scanned_ret = max(cur, *last_scanned_ret);
else
*last_scanned_ret = max(start + len, *last_scanned_ret);
}
return ret;
}
#define CLUSTER_SIZE (SZ_256K)
static_assert(IS_ALIGNED(CLUSTER_SIZE, PAGE_SIZE));
/*
* Defrag one contiguous target range.
*
* @inode: target inode
* @target: target range to defrag
* @pages: locked pages covering the defrag range
* @nr_pages: number of locked pages
*
* Caller should ensure:
*
* - Pages are prepared
* Pages should be locked, no ordered extent in the pages range,
* no writeback.
*
* - Extent bits are locked
*/
static int defrag_one_locked_target(struct btrfs_inode *inode,
struct defrag_target_range *target,
struct page **pages, int nr_pages,
struct extent_state **cached_state)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
struct extent_changeset *data_reserved = NULL;
const u64 start = target->start;
const u64 len = target->len;
unsigned long last_index = (start + len - 1) >> PAGE_SHIFT;
unsigned long start_index = start >> PAGE_SHIFT;
unsigned long first_index = page_index(pages[0]);
int ret = 0;
int i;
ASSERT(last_index - first_index + 1 <= nr_pages);
ret = btrfs_delalloc_reserve_space(inode, &data_reserved, start, len);
if (ret < 0)
return ret;
clear_extent_bit(&inode->io_tree, start, start + len - 1,
EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
EXTENT_DEFRAG, cached_state);
set_extent_defrag(&inode->io_tree, start, start + len - 1, cached_state);
/* Update the page status */
for (i = start_index - first_index; i <= last_index - first_index; i++) {
ClearPageChecked(pages[i]);
btrfs_page_clamp_set_dirty(fs_info, pages[i], start, len);
}
btrfs_delalloc_release_extents(inode, len);
extent_changeset_free(data_reserved);
return ret;
}
static int defrag_one_range(struct btrfs_inode *inode, u64 start, u32 len,
u32 extent_thresh, u64 newer_than, bool do_compress,
u64 *last_scanned_ret)
{
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;
u64 last_index = (start + len - 1) >> PAGE_SHIFT;
u64 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 = kcalloc(nr_pages, sizeof(struct page *), 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;
}
}
for (i = 0; i < nr_pages; i++)
wait_on_page_writeback(pages[i]);
/* Lock the pages range */
lock_extent(&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 needs to be defragged.
*
* And this time we have extent locked already, pass @locked = true
* so that we won't relock the extent range and cause deadlock.
*/
ret = defrag_collect_targets(inode, start, len, extent_thresh,
newer_than, do_compress, true,
&target_list, last_scanned_ret);
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(&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;
}
static int defrag_one_cluster(struct btrfs_inode *inode,
struct file_ra_state *ra,
u64 start, u32 len, u32 extent_thresh,
u64 newer_than, bool do_compress,
unsigned long *sectors_defragged,
unsigned long max_sectors,
u64 *last_scanned_ret)
{
const u32 sectorsize = inode->root->fs_info->sectorsize;
struct defrag_target_range *entry;
struct defrag_target_range *tmp;
LIST_HEAD(target_list);
int ret;
ret = defrag_collect_targets(inode, start, len, extent_thresh,
newer_than, do_compress, false,
&target_list, NULL);
if (ret < 0)
goto out;
list_for_each_entry(entry, &target_list, list) {
u32 range_len = entry->len;
/* Reached or beyond the limit */
if (max_sectors && *sectors_defragged >= max_sectors) {
ret = 1;
break;
}
if (max_sectors)
range_len = min_t(u32, range_len,
(max_sectors - *sectors_defragged) * sectorsize);
/*
* If defrag_one_range() has updated last_scanned_ret,
* our range may already be invalid (e.g. hole punched).
* Skip if our range is before last_scanned_ret, as there is
* no need to defrag the range anymore.
*/
if (entry->start + range_len <= *last_scanned_ret)
continue;
if (ra)
page_cache_sync_readahead(inode->vfs_inode.i_mapping,
ra, NULL, entry->start >> PAGE_SHIFT,
((entry->start + range_len - 1) >> PAGE_SHIFT) -
(entry->start >> PAGE_SHIFT) + 1);
/*
* Here we may not defrag any range if holes are punched before
* we locked the pages.
* But that's fine, it only affects the @sectors_defragged
* accounting.
*/
ret = defrag_one_range(inode, entry->start, range_len,
extent_thresh, newer_than, do_compress,
last_scanned_ret);
if (ret < 0)
break;
*sectors_defragged += range_len >>
inode->root->fs_info->sectorsize_bits;
}
out:
list_for_each_entry_safe(entry, tmp, &target_list, list) {
list_del_init(&entry->list);
kfree(entry);
}
if (ret >= 0)
*last_scanned_ret = max(*last_scanned_ret, start + len);
return ret;
}
/*
* Entry point to file defragmentation.
*
* @inode: inode to be defragged
* @ra: readahead state (can be NUL)
* @range: defrag options including range and flags
* @newer_than: minimum transid to defrag
* @max_to_defrag: max number of sectors to be defragged, if 0, the whole inode
* will be defragged.
*
* Return <0 for error.
* Return >=0 for the number of sectors defragged, and range->start will be updated
* to indicate the file offset where next defrag should be started at.
* (Mostly for autodefrag, which sets @max_to_defrag thus we may exit early without
* defragging all the range).
*/
int btrfs_defrag_file(struct inode *inode, struct file_ra_state *ra,
struct btrfs_ioctl_defrag_range_args *range,
u64 newer_than, unsigned long max_to_defrag)
{
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
unsigned long sectors_defragged = 0;
u64 isize = i_size_read(inode);
u64 cur;
u64 last_byte;
bool do_compress = (range->flags & BTRFS_DEFRAG_RANGE_COMPRESS);
bool ra_allocated = false;
int compress_type = BTRFS_COMPRESS_ZLIB;
int ret = 0;
u32 extent_thresh = range->extent_thresh;
pgoff_t start_index;
if (isize == 0)
return 0;
if (range->start >= isize)
return -EINVAL;
if (do_compress) {
if (range->compress_type >= BTRFS_NR_COMPRESS_TYPES)
return -EINVAL;
if (range->compress_type)
compress_type = range->compress_type;
}
if (extent_thresh == 0)
extent_thresh = SZ_256K;
if (range->start + range->len > range->start) {
/* Got a specific range */
last_byte = min(isize, range->start + range->len);
} else {
/* Defrag until file end */
last_byte = isize;
}
/* Align the range */
cur = round_down(range->start, fs_info->sectorsize);
last_byte = round_up(last_byte, fs_info->sectorsize) - 1;
/*
* If we were not given a ra, allocate a readahead context. As
* readahead is just an optimization, defrag will work without it so
* we don't error out.
*/
if (!ra) {
ra_allocated = true;
ra = kzalloc(sizeof(*ra), GFP_KERNEL);
if (ra)
file_ra_state_init(ra, inode->i_mapping);
}
/*
* Make writeback start from the beginning of the range, so that the
* defrag range can be written sequentially.
*/
start_index = cur >> PAGE_SHIFT;
if (start_index < inode->i_mapping->writeback_index)
inode->i_mapping->writeback_index = start_index;
while (cur < last_byte) {
const unsigned long prev_sectors_defragged = sectors_defragged;
u64 last_scanned = cur;
u64 cluster_end;
if (btrfs_defrag_cancelled(fs_info)) {
ret = -EAGAIN;
break;
}
/* We want the cluster end at page boundary when possible */
cluster_end = (((cur >> PAGE_SHIFT) +
(SZ_256K >> PAGE_SHIFT)) << PAGE_SHIFT) - 1;
cluster_end = min(cluster_end, last_byte);
btrfs_inode_lock(inode, 0);
if (IS_SWAPFILE(inode)) {
ret = -ETXTBSY;
btrfs_inode_unlock(inode, 0);
break;
}
if (!(inode->i_sb->s_flags & SB_ACTIVE)) {
btrfs_inode_unlock(inode, 0);
break;
}
if (do_compress)
BTRFS_I(inode)->defrag_compress = compress_type;
ret = defrag_one_cluster(BTRFS_I(inode), ra, cur,
cluster_end + 1 - cur, extent_thresh,
newer_than, do_compress, &sectors_defragged,
max_to_defrag, &last_scanned);
if (sectors_defragged > prev_sectors_defragged)
balance_dirty_pages_ratelimited(inode->i_mapping);
btrfs_inode_unlock(inode, 0);
if (ret < 0)
break;
cur = max(cluster_end + 1, last_scanned);
if (ret > 0) {
ret = 0;
break;
}
cond_resched();
}
if (ra_allocated)
kfree(ra);
/*
* Update range.start for autodefrag, this will indicate where to start
* in next run.
*/
range->start = cur;
if (sectors_defragged) {
/*
* We have defragged some sectors, for compression case they
* need to be written back immediately.
*/
if (range->flags & BTRFS_DEFRAG_RANGE_START_IO) {
filemap_flush(inode->i_mapping);
if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
&BTRFS_I(inode)->runtime_flags))
filemap_flush(inode->i_mapping);
}
if (range->compress_type == BTRFS_COMPRESS_LZO)
btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
else if (range->compress_type == BTRFS_COMPRESS_ZSTD)
btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
ret = sectors_defragged;
}
if (do_compress) {
btrfs_inode_lock(inode, 0);
BTRFS_I(inode)->defrag_compress = BTRFS_COMPRESS_NONE;
btrfs_inode_unlock(inode, 0);
}
return ret;
}
void __cold btrfs_auto_defrag_exit(void)
{
kmem_cache_destroy(btrfs_inode_defrag_cachep);

902
fs/btrfs/ioctl.c
View File

@ -1039,908 +1039,6 @@ out:
return ret;
}
/*
* Defrag specific helper to get an extent map.
*
* Differences between this and btrfs_get_extent() are:
*
* - No extent_map will be added to inode->extent_tree
* To reduce memory usage in the long run.
*
* - Extra optimization to skip file extents older than @newer_than
* By using btrfs_search_forward() we can skip entire file ranges that
* have extents created in past transactions, because btrfs_search_forward()
* will not visit leaves and nodes with a generation smaller than given
* minimal generation threshold (@newer_than).
*
* Return valid em if we find a file extent matching the requirement.
* Return NULL if we can not find a file extent matching the requirement.
*
* Return ERR_PTR() for error.
*/
static struct extent_map *defrag_get_extent(struct btrfs_inode *inode,
u64 start, u64 newer_than)
{
struct btrfs_root *root = inode->root;
struct btrfs_file_extent_item *fi;
struct btrfs_path path = { 0 };
struct extent_map *em;
struct btrfs_key key;
u64 ino = btrfs_ino(inode);
int ret;
em = alloc_extent_map();
if (!em) {
ret = -ENOMEM;
goto err;
}
key.objectid = ino;
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = start;
if (newer_than) {
ret = btrfs_search_forward(root, &key, &path, newer_than);
if (ret < 0)
goto err;
/* Can't find anything newer */
if (ret > 0)
goto not_found;
} else {
ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
if (ret < 0)
goto err;
}
if (path.slots[0] >= btrfs_header_nritems(path.nodes[0])) {
/*
* If btrfs_search_slot() makes path to point beyond nritems,
* we should not have an empty leaf, as this inode must at
* least have its INODE_ITEM.
*/
ASSERT(btrfs_header_nritems(path.nodes[0]));
path.slots[0] = btrfs_header_nritems(path.nodes[0]) - 1;
}
btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
/* Perfect match, no need to go one slot back */
if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY &&
key.offset == start)
goto iterate;
/* We didn't find a perfect match, needs to go one slot back */
if (path.slots[0] > 0) {
btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY)
path.slots[0]--;
}
iterate:
/* Iterate through the path to find a file extent covering @start */
while (true) {
u64 extent_end;
if (path.slots[0] >= btrfs_header_nritems(path.nodes[0]))
goto next;
btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
/*
* We may go one slot back to INODE_REF/XATTR item, then
* need to go forward until we reach an EXTENT_DATA.
* But we should still has the correct ino as key.objectid.
*/
if (WARN_ON(key.objectid < ino) || key.type < BTRFS_EXTENT_DATA_KEY)
goto next;
/* It's beyond our target range, definitely not extent found */
if (key.objectid > ino || key.type > BTRFS_EXTENT_DATA_KEY)
goto not_found;
/*
* | |<- File extent ->|
* \- start
*
* This means there is a hole between start and key.offset.
*/
if (key.offset > start) {
em->start = start;
em->orig_start = start;
em->block_start = EXTENT_MAP_HOLE;
em->len = key.offset - start;
break;
}
fi = btrfs_item_ptr(path.nodes[0], path.slots[0],
struct btrfs_file_extent_item);
extent_end = btrfs_file_extent_end(&path);
/*
* |<- file extent ->| |
* \- start
*
* We haven't reached start, search next slot.
*/
if (extent_end <= start)
goto next;
/* Now this extent covers @start, convert it to em */
btrfs_extent_item_to_extent_map(inode, &path, fi, false, em);
break;
next:
ret = btrfs_next_item(root, &path);
if (ret < 0)
goto err;
if (ret > 0)
goto not_found;
}
btrfs_release_path(&path);
return em;
not_found:
btrfs_release_path(&path);
free_extent_map(em);
return NULL;
err:
btrfs_release_path(&path);
free_extent_map(em);
return ERR_PTR(ret);
}
static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start,
u64 newer_than, bool locked)
{
struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
struct extent_map *em;
const u32 sectorsize = BTRFS_I(inode)->root->fs_info->sectorsize;
/*
* hopefully we have this extent in the tree already, try without
* the full extent lock
*/
read_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, start, sectorsize);
read_unlock(&em_tree->lock);
/*
* We can get a merged extent, in that case, we need to re-search
* tree to get the original em for defrag.
*
* If @newer_than is 0 or em::generation < newer_than, we can trust
* this em, as either we don't care about the generation, or the
* merged extent map will be rejected anyway.
*/
if (em && test_bit(EXTENT_FLAG_MERGED, &em->flags) &&
newer_than && em->generation >= newer_than) {
free_extent_map(em);
em = NULL;
}
if (!em) {
struct extent_state *cached = NULL;
u64 end = start + sectorsize - 1;
/* get the big lock and read metadata off disk */
if (!locked)
lock_extent(io_tree, start, end, &cached);
em = defrag_get_extent(BTRFS_I(inode), start, newer_than);
if (!locked)
unlock_extent(io_tree, start, end, &cached);
if (IS_ERR(em))
return NULL;
}
return em;
}
static u32 get_extent_max_capacity(const struct btrfs_fs_info *fs_info,
const struct extent_map *em)
{
if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
return BTRFS_MAX_COMPRESSED;
return fs_info->max_extent_size;
}
static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em,
u32 extent_thresh, u64 newer_than, bool locked)
{
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
struct extent_map *next;
bool ret = false;
/* this is the last extent */
if (em->start + em->len >= i_size_read(inode))
return false;
/*
* Here we need to pass @newer_then when checking the next extent, or
* we will hit a case we mark current extent for defrag, but the next
* one will not be a target.
* This will just cause extra IO without really reducing the fragments.
*/
next = defrag_lookup_extent(inode, em->start + em->len, newer_than, locked);
/* No more em or hole */
if (!next || next->block_start >= EXTENT_MAP_LAST_BYTE)
goto out;
if (test_bit(EXTENT_FLAG_PREALLOC, &next->flags))
goto out;
/*
* If the next extent is at its max capacity, defragging current extent
* makes no sense, as the total number of extents won't change.
*/
if (next->len >= get_extent_max_capacity(fs_info, em))
goto out;
/* Skip older extent */
if (next->generation < newer_than)
goto out;
/* Also check extent size */
if (next->len >= extent_thresh)
goto out;
ret = true;
out:
free_extent_map(next);
return ret;
}
/*
* Prepare one page to be defragged.
*
* This will ensure:
*
* - Returned page is locked and has been set up properly.
* - No ordered extent exists in the page.
* - The page is uptodate.
*
* NOTE: Caller should also wait for page writeback after the cluster is
* prepared, here we don't do writeback wait for each page.
*/
static struct page *defrag_prepare_one_page(struct btrfs_inode *inode,
pgoff_t index)
{
struct address_space *mapping = inode->vfs_inode.i_mapping;
gfp_t mask = btrfs_alloc_write_mask(mapping);
u64 page_start = (u64)index << PAGE_SHIFT;
u64 page_end = page_start + PAGE_SIZE - 1;
struct extent_state *cached_state = NULL;
struct page *page;
int ret;
again:
page = find_or_create_page(mapping, index, mask);
if (!page)
return ERR_PTR(-ENOMEM);
/*
* Since we can defragment files opened read-only, we can encounter
* transparent huge pages here (see CONFIG_READ_ONLY_THP_FOR_FS). We
* can't do I/O using huge pages yet, so return an error for now.
* Filesystem transparent huge pages are typically only used for
* executables that explicitly enable them, so this isn't very
* restrictive.
*/
if (PageCompound(page)) {
unlock_page(page);
put_page(page);
return ERR_PTR(-ETXTBSY);
}
ret = set_page_extent_mapped(page);
if (ret < 0) {
unlock_page(page);
put_page(page);
return ERR_PTR(ret);
}
/* Wait for any existing ordered extent in the range */
while (1) {
struct btrfs_ordered_extent *ordered;
lock_extent(&inode->io_tree, page_start, page_end, &cached_state);
ordered = btrfs_lookup_ordered_range(inode, page_start, PAGE_SIZE);
unlock_extent(&inode->io_tree, page_start, page_end,
&cached_state);
if (!ordered)
break;
unlock_page(page);
btrfs_start_ordered_extent(ordered, 1);
btrfs_put_ordered_extent(ordered);
lock_page(page);
/*
* We unlocked the page above, so we need check if it was
* released or not.
*/
if (page->mapping != mapping || !PagePrivate(page)) {
unlock_page(page);
put_page(page);
goto again;
}
}
/*
* Now the page range has no ordered extent any more. Read the page to
* make it uptodate.
*/
if (!PageUptodate(page)) {
btrfs_read_folio(NULL, page_folio(page));
lock_page(page);
if (page->mapping != mapping || !PagePrivate(page)) {
unlock_page(page);
put_page(page);
goto again;
}
if (!PageUptodate(page)) {
unlock_page(page);
put_page(page);
return ERR_PTR(-EIO);
}
}
return page;
}
struct defrag_target_range {
struct list_head list;
u64 start;
u64 len;
};
/*
* Collect all valid target extents.
*
* @start: file offset to lookup
* @len: length to lookup
* @extent_thresh: file extent size threshold, any extent size >= this value
* will be ignored
* @newer_than: only defrag extents newer than this value
* @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 held extent lock
* @target_list: 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,
bool locked, struct list_head *target_list,
u64 *last_scanned_ret)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
bool last_is_target = false;
u64 cur = start;
int ret = 0;
while (cur < start + len) {
struct extent_map *em;
struct defrag_target_range *new;
bool next_mergeable = true;
u64 range_len;
last_is_target = false;
em = defrag_lookup_extent(&inode->vfs_inode, cur,
newer_than, locked);
if (!em)
break;
/*
* If the file extent is an inlined one, we may still want to
* defrag it (fallthrough) if it will cause a regular extent.
* This is for users who want to convert inline extents to
* regular ones through max_inline= mount option.
*/
if (em->block_start == EXTENT_MAP_INLINE &&
em->len <= inode->root->fs_info->max_inline)
goto next;
/* Skip hole/delalloc/preallocated extents */
if (em->block_start == EXTENT_MAP_HOLE ||
em->block_start == EXTENT_MAP_DELALLOC ||
test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
goto next;
/* Skip older extent */
if (em->generation < newer_than)
goto next;
/* This em is under writeback, no need to defrag */
if (em->generation == (u64)-1)
goto next;
/*
* Our start offset might be in the middle of an existing extent
* map, so take that into account.
*/
range_len = em->len - (cur - em->start);
/*
* If this range of the extent map is already flagged for delalloc,
* skip it, because:
*
* 1) We could deadlock later, when trying to reserve space for
* delalloc, because in case we can't immediately reserve space
* the flusher can start delalloc and wait for the respective
* ordered extents to complete. The deadlock would happen
* because we do the space reservation while holding the range
* locked, and starting writeback, or finishing an ordered
* extent, requires locking the range;
*
* 2) If there's delalloc there, it means there's dirty pages for
* which writeback has not started yet (we clean the delalloc
* flag when starting writeback and after creating an ordered
* extent). If we mark pages in an adjacent range for defrag,
* then we will have a larger contiguous range for delalloc,
* very likely resulting in a larger extent after writeback is
* triggered (except in a case of free space fragmentation).
*/
if (test_range_bit(&inode->io_tree, cur, cur + range_len - 1,
EXTENT_DELALLOC, 0, NULL))
goto next;
/*
* For do_compress case, we want to compress all valid file
* extents, thus no @extent_thresh or mergeable check.
*/
if (do_compress)
goto add;
/* Skip too large extent */
if (range_len >= extent_thresh)
goto next;
/*
* Skip extents already at its max capacity, this is mostly for
* compressed extents, which max cap is only 128K.
*/
if (em->len >= get_extent_max_capacity(fs_info, em))
goto next;
/*
* Normally there are no more extents after an inline one, thus
* @next_mergeable will normally be false and not defragged.
* So if an inline extent passed all above checks, just add it
* for defrag, and be converted to regular extents.
*/
if (em->block_start == EXTENT_MAP_INLINE)
goto add;
next_mergeable = defrag_check_next_extent(&inode->vfs_inode, em,
extent_thresh, newer_than, locked);
if (!next_mergeable) {
struct defrag_target_range *last;
/* Empty target list, no way to merge with last entry */
if (list_empty(target_list))
goto next;
last = list_entry(target_list->prev,
struct defrag_target_range, list);
/* Not mergeable with last entry */
if (last->start + last->len != cur)
goto next;
/* Mergeable, fall through to add it to @target_list. */
}
add:
last_is_target = true;
range_len = min(extent_map_end(em), start + len) - cur;
/*
* This one is a good target, check if it can be merged into
* last range of the target list.
*/
if (!list_empty(target_list)) {
struct defrag_target_range *last;
last = list_entry(target_list->prev,
struct defrag_target_range, list);
ASSERT(last->start + last->len <= cur);
if (last->start + last->len == cur) {
/* Mergeable, enlarge the last entry */
last->len += range_len;
goto next;
}
/* Fall through to allocate a new entry */
}
/* Allocate new defrag_target_range */
new = kmalloc(sizeof(*new), GFP_NOFS);
if (!new) {
free_extent_map(em);
ret = -ENOMEM;
break;
}
new->start = cur;
new->len = range_len;
list_add_tail(&new->list, target_list);
next:
cur = extent_map_end(em);
free_extent_map(em);
}
if (ret < 0) {
struct defrag_target_range *entry;
struct defrag_target_range *tmp;
list_for_each_entry_safe(entry, tmp, target_list, list) {
list_del_init(&entry->list);
kfree(entry);
}
}
if (!ret && last_scanned_ret) {
/*
* If the last extent is not a target, the caller can skip to
* the end of that extent.
* Otherwise, we can only go the end of the specified range.
*/
if (!last_is_target)
*last_scanned_ret = max(cur, *last_scanned_ret);
else
*last_scanned_ret = max(start + len, *last_scanned_ret);
}
return ret;
}
#define CLUSTER_SIZE (SZ_256K)
static_assert(IS_ALIGNED(CLUSTER_SIZE, PAGE_SIZE));
/*
* Defrag one contiguous target range.
*
* @inode: target inode
* @target: target range to defrag
* @pages: locked pages covering the defrag range
* @nr_pages: number of locked pages
*
* Caller should ensure:
*
* - Pages are prepared
* Pages should be locked, no ordered extent in the pages range,
* no writeback.
*
* - Extent bits are locked
*/
static int defrag_one_locked_target(struct btrfs_inode *inode,
struct defrag_target_range *target,
struct page **pages, int nr_pages,
struct extent_state **cached_state)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
struct extent_changeset *data_reserved = NULL;
const u64 start = target->start;
const u64 len = target->len;
unsigned long last_index = (start + len - 1) >> PAGE_SHIFT;
unsigned long start_index = start >> PAGE_SHIFT;
unsigned long first_index = page_index(pages[0]);
int ret = 0;
int i;
ASSERT(last_index - first_index + 1 <= nr_pages);
ret = btrfs_delalloc_reserve_space(inode, &data_reserved, start, len);
if (ret < 0)
return ret;
clear_extent_bit(&inode->io_tree, start, start + len - 1,
EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
EXTENT_DEFRAG, cached_state);
set_extent_defrag(&inode->io_tree, start, start + len - 1, cached_state);
/* Update the page status */
for (i = start_index - first_index; i <= last_index - first_index; i++) {
ClearPageChecked(pages[i]);
btrfs_page_clamp_set_dirty(fs_info, pages[i], start, len);
}
btrfs_delalloc_release_extents(inode, len);
extent_changeset_free(data_reserved);
return ret;
}
static int defrag_one_range(struct btrfs_inode *inode, u64 start, u32 len,
u32 extent_thresh, u64 newer_than, bool do_compress,
u64 *last_scanned_ret)
{
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;
u64 last_index = (start + len - 1) >> PAGE_SHIFT;
u64 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 = kcalloc(nr_pages, sizeof(struct page *), 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;
}
}
for (i = 0; i < nr_pages; i++)
wait_on_page_writeback(pages[i]);
/* Lock the pages range */
lock_extent(&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 needs to be defragged.
*
* And this time we have extent locked already, pass @locked = true
* so that we won't relock the extent range and cause deadlock.
*/
ret = defrag_collect_targets(inode, start, len, extent_thresh,
newer_than, do_compress, true,
&target_list, last_scanned_ret);
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(&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;
}
static int defrag_one_cluster(struct btrfs_inode *inode,
struct file_ra_state *ra,
u64 start, u32 len, u32 extent_thresh,
u64 newer_than, bool do_compress,
unsigned long *sectors_defragged,
unsigned long max_sectors,
u64 *last_scanned_ret)
{
const u32 sectorsize = inode->root->fs_info->sectorsize;
struct defrag_target_range *entry;
struct defrag_target_range *tmp;
LIST_HEAD(target_list);
int ret;
ret = defrag_collect_targets(inode, start, len, extent_thresh,
newer_than, do_compress, false,
&target_list, NULL);
if (ret < 0)
goto out;
list_for_each_entry(entry, &target_list, list) {
u32 range_len = entry->len;
/* Reached or beyond the limit */
if (max_sectors && *sectors_defragged >= max_sectors) {
ret = 1;
break;
}
if (max_sectors)
range_len = min_t(u32, range_len,
(max_sectors - *sectors_defragged) * sectorsize);
/*
* If defrag_one_range() has updated last_scanned_ret,
* our range may already be invalid (e.g. hole punched).
* Skip if our range is before last_scanned_ret, as there is
* no need to defrag the range anymore.
*/
if (entry->start + range_len <= *last_scanned_ret)
continue;
if (ra)
page_cache_sync_readahead(inode->vfs_inode.i_mapping,
ra, NULL, entry->start >> PAGE_SHIFT,
((entry->start + range_len - 1) >> PAGE_SHIFT) -
(entry->start >> PAGE_SHIFT) + 1);
/*
* Here we may not defrag any range if holes are punched before
* we locked the pages.
* But that's fine, it only affects the @sectors_defragged
* accounting.
*/
ret = defrag_one_range(inode, entry->start, range_len,
extent_thresh, newer_than, do_compress,
last_scanned_ret);
if (ret < 0)
break;
*sectors_defragged += range_len >>
inode->root->fs_info->sectorsize_bits;
}
out:
list_for_each_entry_safe(entry, tmp, &target_list, list) {
list_del_init(&entry->list);
kfree(entry);
}
if (ret >= 0)
*last_scanned_ret = max(*last_scanned_ret, start + len);
return ret;
}
/*
* Entry point to file defragmentation.
*
* @inode: inode to be defragged
* @ra: readahead state (can be NUL)
* @range: defrag options including range and flags
* @newer_than: minimum transid to defrag
* @max_to_defrag: max number of sectors to be defragged, if 0, the whole inode
* will be defragged.
*
* Return <0 for error.
* Return >=0 for the number of sectors defragged, and range->start will be updated
* to indicate the file offset where next defrag should be started at.
* (Mostly for autodefrag, which sets @max_to_defrag thus we may exit early without
* defragging all the range).
*/
int btrfs_defrag_file(struct inode *inode, struct file_ra_state *ra,
struct btrfs_ioctl_defrag_range_args *range,
u64 newer_than, unsigned long max_to_defrag)
{
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
unsigned long sectors_defragged = 0;
u64 isize = i_size_read(inode);
u64 cur;
u64 last_byte;
bool do_compress = range->flags & BTRFS_DEFRAG_RANGE_COMPRESS;
bool ra_allocated = false;
int compress_type = BTRFS_COMPRESS_ZLIB;
int ret = 0;
u32 extent_thresh = range->extent_thresh;
pgoff_t start_index;
if (isize == 0)
return 0;
if (range->start >= isize)
return -EINVAL;
if (do_compress) {
if (range->compress_type >= BTRFS_NR_COMPRESS_TYPES)
return -EINVAL;
if (range->compress_type)
compress_type = range->compress_type;
}
if (extent_thresh == 0)
extent_thresh = SZ_256K;
if (range->start + range->len > range->start) {
/* Got a specific range */
last_byte = min(isize, range->start + range->len);
} else {
/* Defrag until file end */
last_byte = isize;
}
/* Align the range */
cur = round_down(range->start, fs_info->sectorsize);
last_byte = round_up(last_byte, fs_info->sectorsize) - 1;
/*
* If we were not given a ra, allocate a readahead context. As
* readahead is just an optimization, defrag will work without it so
* we don't error out.
*/
if (!ra) {
ra_allocated = true;
ra = kzalloc(sizeof(*ra), GFP_KERNEL);
if (ra)
file_ra_state_init(ra, inode->i_mapping);
}
/*
* Make writeback start from the beginning of the range, so that the
* defrag range can be written sequentially.
*/
start_index = cur >> PAGE_SHIFT;
if (start_index < inode->i_mapping->writeback_index)
inode->i_mapping->writeback_index = start_index;
while (cur < last_byte) {
const unsigned long prev_sectors_defragged = sectors_defragged;
u64 last_scanned = cur;
u64 cluster_end;
if (btrfs_defrag_cancelled(fs_info)) {
ret = -EAGAIN;
break;
}
/* We want the cluster end at page boundary when possible */
cluster_end = (((cur >> PAGE_SHIFT) +
(SZ_256K >> PAGE_SHIFT)) << PAGE_SHIFT) - 1;
cluster_end = min(cluster_end, last_byte);
btrfs_inode_lock(inode, 0);
if (IS_SWAPFILE(inode)) {
ret = -ETXTBSY;
btrfs_inode_unlock(inode, 0);
break;
}
if (!(inode->i_sb->s_flags & SB_ACTIVE)) {
btrfs_inode_unlock(inode, 0);
break;
}
if (do_compress)
BTRFS_I(inode)->defrag_compress = compress_type;
ret = defrag_one_cluster(BTRFS_I(inode), ra, cur,
cluster_end + 1 - cur, extent_thresh,
newer_than, do_compress, &sectors_defragged,
max_to_defrag, &last_scanned);
if (sectors_defragged > prev_sectors_defragged)
balance_dirty_pages_ratelimited(inode->i_mapping);
btrfs_inode_unlock(inode, 0);
if (ret < 0)
break;
cur = max(cluster_end + 1, last_scanned);
if (ret > 0) {
ret = 0;
break;
}
cond_resched();
}
if (ra_allocated)
kfree(ra);
/*
* Update range.start for autodefrag, this will indicate where to start
* in next run.
*/
range->start = cur;
if (sectors_defragged) {
/*
* We have defragged some sectors, for compression case they
* need to be written back immediately.
*/
if (range->flags & BTRFS_DEFRAG_RANGE_START_IO) {
filemap_flush(inode->i_mapping);
if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
&BTRFS_I(inode)->runtime_flags))
filemap_flush(inode->i_mapping);
}
if (range->compress_type == BTRFS_COMPRESS_LZO)
btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
else if (range->compress_type == BTRFS_COMPRESS_ZSTD)
btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
ret = sectors_defragged;
}
if (do_compress) {
btrfs_inode_lock(inode, 0);
BTRFS_I(inode)->defrag_compress = BTRFS_COMPRESS_NONE;
btrfs_inode_unlock(inode, 0);
}
return ret;
}
/*
* Try to start exclusive operation @type or cancel it if it's running.
*