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Btrfs: make find_first_extent_bit be able to cache any state 

Right now the only caller of find_first_extent_bit() that is interested
in caching extent states (transaction or log commit), never gets an extent
state cached. This is because find_first_extent_bit() only caches states
that have at least one of the flags EXTENT_IOBITS or EXTENT_BOUNDARY, and
the transaction/log commit caller always passes a tree that doesn't have
ever extent states with any of those flags (they can only have one of the
following flags: EXTENT_DIRTY, EXTENT_NEW or EXTENT_NEED_WAIT).

This change together with the following one in the patch series (titled
"Btrfs: avoid returning -ENOMEM in convert_extent_bit() too early") will
help reduce significantly the chances of calls to convert_extent_bit()
fail with -ENOMEM when called from the transaction/log commit code.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Filipe Manana 2014-10-13 12:28:38 +01:00 committed by Chris Mason
parent 663dfbb077
commit e38e2ed701
2 changed files with 15 additions and 4 deletions
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16
fs/btrfs/extent_io.c
View File

@ -796,17 +796,25 @@ static void set_state_bits(struct extent_io_tree *tree,
state->state |= bits_to_set;
}
static void cache_state(struct extent_state *state,
struct extent_state **cached_ptr)
static void cache_state_if_flags(struct extent_state *state,
struct extent_state **cached_ptr,
const u64 flags)
{
if (cached_ptr && !(*cached_ptr)) {
if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY)) {
if (!flags || (state->state & flags)) {
*cached_ptr = state;
atomic_inc(&state->refs);
}
}
}
static void cache_state(struct extent_state *state,
struct extent_state **cached_ptr)
{
return cache_state_if_flags(state, cached_ptr,
EXTENT_IOBITS | EXTENT_BOUNDARY);
}
/*
* set some bits on a range in the tree. This may require allocations or
* sleeping, so the gfp mask is used to indicate what is allowed.
@ -1482,7 +1490,7 @@ int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
state = find_first_extent_bit_state(tree, start, bits);
got_it:
if (state) {
cache_state(state, cached_state);
cache_state_if_flags(state, cached_state, 0);
*start_ret = state->start;
*end_ret = state->end;
ret = 0;

3
fs/btrfs/transaction.c
View File

@ -883,6 +883,7 @@ int btrfs_write_marked_extents(struct btrfs_root *root,
werr = err;
else if (wait_writeback)
werr = filemap_fdatawait_range(mapping, start, end);
free_extent_state(cached_state);
cached_state = NULL;
cond_resched();
start = end + 1;
@ -927,6 +928,8 @@ int btrfs_wait_marked_extents(struct btrfs_root *root,
err = filemap_fdatawait_range(mapping, start, end);
if (err)
werr = err;
free_extent_state(cached_state);
cached_state = NULL;
cond_resched();
start = end + 1;
}