bcachefs: Rework fiemap transaction restart handling
Restart handling in the previous patch was incorrect, so: move btree operations into a separate helper, and run it with a lockrestart_do(). Additionally, clarify whether pagecache or the btree takes precedence. Right now, the btree takes precedence: this is incorrect, but it's needed to pass fstests. Add a giant comment explaining why. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet
parent
b9b0494017
commit
d1b0f9aa73
225
fs/bcachefs/fs.c
225
fs/bcachefs/fs.c
|
|
@ -1274,6 +1274,8 @@ static int bch2_fill_extent(struct bch_fs *c,
|
|||
struct bkey_s_c k = bkey_i_to_s_c(fe->kbuf.k);
|
||||
unsigned flags = fe->flags;
|
||||
|
||||
BUG_ON(!k.k->size);
|
||||
|
||||
if (bkey_extent_is_direct_data(k.k)) {
|
||||
struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
|
||||
const union bch_extent_entry *entry;
|
||||
|
|
@ -1326,36 +1328,6 @@ static int bch2_fill_extent(struct bch_fs *c,
|
|||
}
|
||||
}
|
||||
|
||||
static int bch2_fiemap_extent(struct btree_trans *trans,
|
||||
struct btree_iter *iter, struct bkey_s_c k,
|
||||
struct bch_fiemap_extent *cur)
|
||||
{
|
||||
s64 offset_into_extent = iter->pos.offset - bkey_start_offset(k.k);
|
||||
unsigned sectors = k.k->size - offset_into_extent;
|
||||
|
||||
bch2_bkey_buf_reassemble(&cur->kbuf, trans->c, k);
|
||||
|
||||
enum btree_id data_btree = BTREE_ID_extents;
|
||||
int ret = bch2_read_indirect_extent(trans, &data_btree, &offset_into_extent,
|
||||
&cur->kbuf);
|
||||
if (ret)
|
||||
return ret;
|
||||
|
||||
k = bkey_i_to_s_c(cur->kbuf.k);
|
||||
sectors = min_t(unsigned, sectors, k.k->size - offset_into_extent);
|
||||
|
||||
bch2_cut_front(POS(k.k->p.inode,
|
||||
bkey_start_offset(k.k) + offset_into_extent),
|
||||
cur->kbuf.k);
|
||||
bch2_key_resize(&cur->kbuf.k->k, sectors);
|
||||
cur->kbuf.k->k.p = iter->pos;
|
||||
cur->kbuf.k->k.p.offset += cur->kbuf.k->k.size;
|
||||
|
||||
cur->flags = 0;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Scan a range of an inode for data in pagecache.
|
||||
*
|
||||
|
|
@ -1371,13 +1343,19 @@ bch2_fiemap_hole_pagecache(struct inode *vinode, u64 *start, u64 *end,
|
|||
dstart = bch2_seek_pagecache_data(vinode, *start, *end, 0, nonblock);
|
||||
if (dstart < 0)
|
||||
return dstart;
|
||||
if (dstart >= *end)
|
||||
return -ENOENT;
|
||||
|
||||
if (dstart == *end) {
|
||||
*start = dstart;
|
||||
return 0;
|
||||
}
|
||||
|
||||
dend = bch2_seek_pagecache_hole(vinode, dstart, *end, 0, nonblock);
|
||||
if (dend < 0)
|
||||
return dend;
|
||||
|
||||
/* race */
|
||||
BUG_ON(dstart == dend);
|
||||
|
||||
*start = dstart;
|
||||
*end = dend;
|
||||
return 0;
|
||||
|
|
@ -1387,18 +1365,15 @@ bch2_fiemap_hole_pagecache(struct inode *vinode, u64 *start, u64 *end,
|
|||
* Scan a range of pagecache that corresponds to a file mapping hole in the
|
||||
* extent btree. If data is found, fake up an extent key so it looks like a
|
||||
* delalloc extent to the rest of the fiemap processing code.
|
||||
*
|
||||
* Returns 0 if cached data was found, -ENOENT if not.
|
||||
*/
|
||||
static int
|
||||
bch2_fiemap_hole(struct btree_trans *trans, struct inode *vinode, u64 start,
|
||||
u64 end, struct bch_fiemap_extent *cur)
|
||||
bch2_next_fiemap_pagecache_extent(struct btree_trans *trans, struct bch_inode_info *inode,
|
||||
u64 start, u64 end, struct bch_fiemap_extent *cur)
|
||||
{
|
||||
struct bch_fs *c = vinode->i_sb->s_fs_info;
|
||||
struct bch_inode_info *ei = to_bch_ei(vinode);
|
||||
struct bch_fs *c = trans->c;
|
||||
struct bkey_i_extent *delextent;
|
||||
struct bch_extent_ptr ptr = {};
|
||||
loff_t dstart = start, dend = end;
|
||||
loff_t dstart = start << 9, dend = end << 9;
|
||||
int ret;
|
||||
|
||||
/*
|
||||
|
|
@ -1411,13 +1386,10 @@ bch2_fiemap_hole(struct btree_trans *trans, struct inode *vinode, u64 start,
|
|||
* fundamentally racy with writeback anyways. Therefore, just report the
|
||||
* range as delalloc regardless of whether we have to cycle trans locks.
|
||||
*/
|
||||
ret = bch2_fiemap_hole_pagecache(vinode, &dstart, &dend, true);
|
||||
if (ret == -EAGAIN) {
|
||||
/* open coded drop_locks_do() to relock even on error */
|
||||
bch2_trans_unlock(trans);
|
||||
ret = bch2_fiemap_hole_pagecache(vinode, &dstart, &dend, false);
|
||||
bch2_trans_relock(trans);
|
||||
}
|
||||
ret = bch2_fiemap_hole_pagecache(&inode->v, &dstart, &dend, true);
|
||||
if (ret == -EAGAIN)
|
||||
ret = drop_locks_do(trans,
|
||||
bch2_fiemap_hole_pagecache(&inode->v, &dstart, &dend, false));
|
||||
if (ret < 0)
|
||||
return ret;
|
||||
|
||||
|
|
@ -1428,8 +1400,8 @@ bch2_fiemap_hole(struct btree_trans *trans, struct inode *vinode, u64 start,
|
|||
*/
|
||||
bch2_bkey_buf_realloc(&cur->kbuf, c, sizeof(*delextent) / sizeof(u64));
|
||||
delextent = bkey_extent_init(cur->kbuf.k);
|
||||
delextent->k.p = POS(ei->v.i_ino, dstart >> 9);
|
||||
bch2_key_resize(&delextent->k, (dend - dstart) >> 9);
|
||||
delextent->k.p = POS(inode->ei_inum.inum, dend >> 9);
|
||||
delextent->k.size = (dend - dstart) >> 9;
|
||||
bch2_bkey_append_ptr(&delextent->k_i, ptr);
|
||||
|
||||
cur->flags = FIEMAP_EXTENT_DELALLOC;
|
||||
|
|
@ -1437,115 +1409,142 @@ bch2_fiemap_hole(struct btree_trans *trans, struct inode *vinode, u64 start,
|
|||
return 0;
|
||||
}
|
||||
|
||||
static int bch2_next_fiemap_extent(struct btree_trans *trans,
|
||||
struct bch_inode_info *inode,
|
||||
u64 start, u64 end,
|
||||
struct bch_fiemap_extent *cur)
|
||||
{
|
||||
u32 snapshot;
|
||||
int ret = bch2_subvolume_get_snapshot(trans, inode->ei_inum.subvol, &snapshot);
|
||||
if (ret)
|
||||
return ret;
|
||||
|
||||
struct btree_iter iter;
|
||||
bch2_trans_iter_init(trans, &iter, BTREE_ID_extents,
|
||||
SPOS(inode->ei_inum.inum, start, snapshot), 0);
|
||||
|
||||
struct bkey_s_c k =
|
||||
bch2_btree_iter_peek_max(trans, &iter, POS(inode->ei_inum.inum, end));
|
||||
ret = bkey_err(k);
|
||||
if (ret)
|
||||
goto err;
|
||||
|
||||
ret = bch2_next_fiemap_pagecache_extent(trans, inode, start, end, cur);
|
||||
if (ret)
|
||||
goto err;
|
||||
|
||||
struct bpos pagecache_start = bkey_start_pos(&cur->kbuf.k->k);
|
||||
|
||||
/*
|
||||
* Does the pagecache or the btree take precedence?
|
||||
*
|
||||
* It _should_ be the pagecache, so that we correctly report delalloc
|
||||
* extents when dirty in the pagecache (we're COW, after all).
|
||||
*
|
||||
* But we'd have to add per-sector writeback tracking to
|
||||
* bch_folio_state, otherwise we report delalloc extents for clean
|
||||
* cached data in the pagecache.
|
||||
*
|
||||
* We should do this, but even then fiemap won't report stable mappings:
|
||||
* on bcachefs data moves around in the background (copygc, rebalance)
|
||||
* and we don't provide a way for userspace to lock that out.
|
||||
*/
|
||||
if (k.k &&
|
||||
bkey_le(bpos_max(iter.pos, bkey_start_pos(k.k)),
|
||||
pagecache_start)) {
|
||||
bch2_bkey_buf_reassemble(&cur->kbuf, trans->c, k);
|
||||
bch2_cut_front(iter.pos, cur->kbuf.k);
|
||||
bch2_cut_back(POS(inode->ei_inum.inum, end), cur->kbuf.k);
|
||||
cur->flags = 0;
|
||||
} else if (k.k) {
|
||||
bch2_cut_back(bkey_start_pos(k.k), cur->kbuf.k);
|
||||
}
|
||||
|
||||
if (cur->kbuf.k->k.type == KEY_TYPE_reflink_p) {
|
||||
unsigned sectors = cur->kbuf.k->k.size;
|
||||
s64 offset_into_extent = 0;
|
||||
enum btree_id data_btree = BTREE_ID_extents;
|
||||
int ret = bch2_read_indirect_extent(trans, &data_btree, &offset_into_extent,
|
||||
&cur->kbuf);
|
||||
if (ret)
|
||||
goto err;
|
||||
|
||||
struct bkey_i *k = cur->kbuf.k;
|
||||
sectors = min_t(unsigned, sectors, k->k.size - offset_into_extent);
|
||||
|
||||
bch2_cut_front(POS(k->k.p.inode,
|
||||
bkey_start_offset(&k->k) + offset_into_extent),
|
||||
k);
|
||||
bch2_key_resize(&k->k, sectors);
|
||||
k->k.p = iter.pos;
|
||||
k->k.p.offset += k->k.size;
|
||||
}
|
||||
err:
|
||||
bch2_trans_iter_exit(trans, &iter);
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int bch2_fiemap(struct inode *vinode, struct fiemap_extent_info *info,
|
||||
u64 start, u64 len)
|
||||
{
|
||||
struct bch_fs *c = vinode->i_sb->s_fs_info;
|
||||
struct bch_inode_info *ei = to_bch_ei(vinode);
|
||||
struct btree_trans *trans;
|
||||
struct btree_iter iter;
|
||||
struct bkey_s_c k;
|
||||
struct bch_fiemap_extent cur, prev;
|
||||
bool have_extent = false;
|
||||
int ret = 0;
|
||||
|
||||
ret = fiemap_prep(&ei->v, info, start, &len, 0);
|
||||
if (ret)
|
||||
return ret;
|
||||
|
||||
struct bpos end = POS(ei->v.i_ino, (start + len) >> 9);
|
||||
if (start + len < start)
|
||||
return -EINVAL;
|
||||
|
||||
start >>= 9;
|
||||
u64 end = (start + len) >> 9;
|
||||
|
||||
bch2_bkey_buf_init(&cur.kbuf);
|
||||
bch2_bkey_buf_init(&prev.kbuf);
|
||||
bkey_init(&prev.kbuf.k->k);
|
||||
|
||||
trans = bch2_trans_get(c);
|
||||
|
||||
bch2_trans_iter_init(trans, &iter, BTREE_ID_extents,
|
||||
POS(ei->v.i_ino, start), 0);
|
||||
|
||||
while (!ret || bch2_err_matches(ret, BCH_ERR_transaction_restart)) {
|
||||
bool have_delalloc = false;
|
||||
|
||||
bch2_trans_begin(trans);
|
||||
|
||||
u32 snapshot;
|
||||
ret = bch2_subvolume_get_snapshot(trans, ei->ei_inum.subvol, &snapshot);
|
||||
while (start < end) {
|
||||
ret = lockrestart_do(trans,
|
||||
bch2_next_fiemap_extent(trans, ei, start, end, &cur));
|
||||
if (ret)
|
||||
continue;
|
||||
goto err;
|
||||
|
||||
bch2_btree_iter_set_snapshot(trans, &iter, snapshot);
|
||||
BUG_ON(bkey_start_offset(&cur.kbuf.k->k) < start);
|
||||
BUG_ON(cur.kbuf.k->k.p.offset > end);
|
||||
|
||||
k = bch2_btree_iter_peek_max(trans, &iter, end);
|
||||
ret = bkey_err(k);
|
||||
if (ret)
|
||||
continue;
|
||||
|
||||
if (!k.k)
|
||||
if (bkey_start_offset(&cur.kbuf.k->k) == end)
|
||||
break;
|
||||
|
||||
/*
|
||||
* If a hole exists before the start of the extent key, scan the
|
||||
* range for pagecache data that might be pending writeback and
|
||||
* thus not yet exist in the extent tree.
|
||||
*/
|
||||
if (iter.pos.offset > start) {
|
||||
ret = bch2_fiemap_hole(trans, vinode, start << 9,
|
||||
iter.pos.offset << 9, &cur);
|
||||
if (!ret)
|
||||
have_delalloc = true;
|
||||
else if (ret != -ENOENT)
|
||||
break;
|
||||
}
|
||||
|
||||
/* process the current key if there's no delalloc to report */
|
||||
if (!have_delalloc) {
|
||||
if (!bkey_extent_is_data(k.k) &&
|
||||
k.k->type != KEY_TYPE_reservation) {
|
||||
start = bkey_start_offset(k.k) + k.k->size;
|
||||
bch2_btree_iter_advance(trans, &iter);
|
||||
continue;
|
||||
}
|
||||
|
||||
ret = bch2_fiemap_extent(trans, &iter, k, &cur);
|
||||
if (ret)
|
||||
break;
|
||||
}
|
||||
|
||||
/*
|
||||
* Store the current extent in prev so we can flag the last
|
||||
* extent on the way out.
|
||||
*/
|
||||
bch2_bkey_buf_realloc(&prev.kbuf, c, cur.kbuf.k->k.u64s);
|
||||
start = cur.kbuf.k->k.p.offset;
|
||||
|
||||
if (have_extent) {
|
||||
if (!bkey_deleted(&prev.kbuf.k->k)) {
|
||||
bch2_trans_unlock(trans);
|
||||
ret = bch2_fill_extent(c, info, &prev);
|
||||
if (ret)
|
||||
break;
|
||||
goto err;
|
||||
}
|
||||
|
||||
bkey_copy(prev.kbuf.k, cur.kbuf.k);
|
||||
bch2_bkey_buf_copy(&prev.kbuf, c, cur.kbuf.k);
|
||||
prev.flags = cur.flags;
|
||||
have_extent = true;
|
||||
|
||||
bch2_btree_iter_set_pos(trans, &iter, POS(iter.pos.inode, start));
|
||||
}
|
||||
bch2_trans_iter_exit(trans, &iter);
|
||||
|
||||
if (!ret && have_extent) {
|
||||
if (!bkey_deleted(&prev.kbuf.k->k)) {
|
||||
bch2_trans_unlock(trans);
|
||||
prev.flags |= FIEMAP_EXTENT_LAST;
|
||||
ret = bch2_fill_extent(c, info, &prev);
|
||||
}
|
||||
|
||||
err:
|
||||
bch2_trans_put(trans);
|
||||
bch2_bkey_buf_exit(&cur.kbuf, c);
|
||||
bch2_bkey_buf_exit(&prev.kbuf, c);
|
||||
return ret < 0 ? ret : 0;
|
||||
|
||||
return bch2_err_class(ret < 0 ? ret : 0);
|
||||
}
|
||||
|
||||
static const struct vm_operations_struct bch_vm_ops = {
|
||||
|
|
|
|||
Loading…
Reference in New Issue