[PATCH 05/10] libext2fs: invalidate cached blocks when freeing them

Darrick J. Wong
2025-08-21T01:14:24Z

When we're freeing blocks, we should tell the IO manager to drop them
from any cache it might be maintaining to improve performance.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
lib/ext2fs/ext2_io.h | 8 +++++++-
debian/libext2fs2t64.symbols | 1 +
lib/ext2fs/alloc_stats.c | 6 ++++++
lib/ext2fs/io_manager.c | 9 +++++++++
lib/ext2fs/unix_io.c | 35 +++++++++++++++++++++++++++++++++++
5 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/lib/ext2fs/ext2_io.h b/lib/ext2fs/ext2_io.h
index f53983b30996b4..26ecd128954a0e 100644
--- a/lib/ext2fs/ext2_io.h
+++ b/lib/ext2fs/ext2_io.h
@@ -103,7 +103,10 @@ struct struct_io_manager {
errcode_t (*zeroout)(io_channel channel, unsigned long long block,
unsigned long long count);
errcode_t (*get_fd)(io_channel channel, int *fd);
- long reserved[13];
+ errcode_t (*invalidate_blocks)(io_channel channel,
+ unsigned long long block,
+ unsigned long long count);
+ long reserved[12];
};

#define IO_FLAG_RW 0x0001
@@ -147,6 +150,9 @@ extern errcode_t io_channel_cache_readahead(io_channel io,
unsigned long long block,
unsigned long long count);
extern errcode_t io_channel_get_fd(io_channel io, int *fd);
+extern errcode_t io_channel_invalidate_blocks(io_channel io,
+ unsigned long long block,
+ unsigned long long count);

#ifdef _WIN32
/* windows_io.c */
diff --git a/debian/libext2fs2t64.symbols b/debian/libext2fs2t64.symbols
index 8e3214ee31e337..864a284b940009 100644
--- a/debian/libext2fs2t64.symbols
+++ b/debian/libext2fs2t64.symbols
@@ -694,6 +694,7 @@ libext2fs.so.2 libext2fs2t64 #MINVER#
io_channel_cache_readahead@Base 1.43
io_channel_discard@Base 1.42
io_channel_get_fd@Base 1.47.99
+ io_channel_invalidate_blocks@Base 1.47.99
io_channel_read_blk64@Base 1.41.1
io_channel_set_options@Base 1.37
io_channel_write_blk64@Base 1.41.1
diff --git a/lib/ext2fs/alloc_stats.c b/lib/ext2fs/alloc_stats.c
index 95a6438f252e0f..68bbe6807a8ed3 100644
--- a/lib/ext2fs/alloc_stats.c
+++ b/lib/ext2fs/alloc_stats.c
@@ -82,6 +82,9 @@ void ext2fs_block_alloc_stats2(ext2_filsys fs, blk64_t blk, int inuse)
-inuse * (blk64_t) EXT2FS_CLUSTER_RATIO(fs));
ext2fs_mark_super_dirty(fs);
ext2fs_mark_bb_dirty(fs);
+ if (inuse < 0)
+ io_channel_invalidate_blocks(fs->io, blk,
+ EXT2FS_CLUSTER_RATIO(fs));
if (fs->block_alloc_stats)
(fs->block_alloc_stats)(fs, (blk64_t) blk, inuse);
}
@@ -144,11 +147,14 @@ void ext2fs_block_alloc_stats_range(ext2_filsys fs, blk64_t blk,
ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
ext2fs_group_desc_csum_set(fs, group);
ext2fs_free_blocks_count_add(fs->super, -inuse * (blk64_t) n);
+
blk += n;
num -= n;
}
ext2fs_mark_super_dirty(fs);
ext2fs_mark_bb_dirty(fs);
+ if (inuse < 0)
+ io_channel_invalidate_blocks(fs->io, orig_blk, orig_num);
if (fs->block_alloc_stats_range)
(fs->block_alloc_stats_range)(fs, orig_blk, orig_num, inuse);
}
diff --git a/lib/ext2fs/io_manager.c b/lib/ext2fs/io_manager.c
index 6b4dca5e4dbca2..c91fab4eb290d5 100644
--- a/lib/ext2fs/io_manager.c
+++ b/lib/ext2fs/io_manager.c
@@ -158,3 +158,12 @@ errcode_t io_channel_get_fd(io_channel io, int *fd)

return io->manager->get_fd(io, fd);
}
+
+errcode_t io_channel_invalidate_blocks(io_channel io, unsigned long long block,
+ unsigned long long count)
+{
+ if (!io->manager->invalidate_blocks)
+ return EXT2_ET_OP_NOT_SUPPORTED;
+
+ return io->manager->invalidate_blocks(io, block, count);
+}
diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index 61ecdc9b8b56b2..0d1006207c60cd 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -667,6 +667,25 @@ static errcode_t reuse_cache(io_channel channel,
#define FLUSH_INVALIDATE 0x01
#define FLUSH_NOLOCK 0x02

+/* Remove blocks from the cache. Dirty contents are discarded. */
+static void invalidate_cached_blocks(io_channel channel,
+ struct unix_private_data *data,
+ unsigned long long block,
+ unsigned long long count)
+{
+ struct unix_cache *cache;
+ int i;
+
+ mutex_lock(data, CACHE_MTX);
+ for (i = 0, cache = data->cache; i < data->cache_size; i++, cache++) {
+ if (!cache->in_use || cache->block < block ||
+ cache->block >= block + count)
+ continue;
+ cache->in_use = 0;
+ }
+ mutex_unlock(data, CACHE_MTX);
+}
+
/*
* Flush all of the blocks in the cache
*/
@@ -1716,6 +1735,20 @@ static errcode_t unix_get_fd(io_channel channel, int *fd)
return 0;
}

+static errcode_t unix_invalidate_blocks(io_channel channel,
+ unsigned long long block,
+ unsigned long long count)
+{
+ struct unix_private_data *data;
+
+ EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+ data = (struct unix_private_data *) channel->private_data;
+ EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+ invalidate_cached_blocks(channel, data, block, count);
+ return 0;
+}
+
#if __GNUC_PREREQ (4, 6)
#pragma GCC diagnostic pop
#endif
@@ -1738,6 +1771,7 @@ static struct struct_io_manager struct_unix_manager = {
.cache_readahead = unix_cache_readahead,
.zeroout = unix_zeroout,
.get_fd = unix_get_fd,
+ .invalidate_blocks = unix_invalidate_blocks,
};

io_manager unix_io_manager = &struct_unix_manager;
@@ -1760,6 +1794,7 @@ static struct struct_io_manager struct_unixfd_manager = {
.cache_readahead = unix_cache_readahead,
.zeroout = unix_zeroout,
.get_fd = unix_get_fd,
+ .invalidate_blocks = unix_invalidate_blocks,
};

io_manager unixfd_io_manager = &struct_unixfd_manager;