[PATCH 04/10] libext2fs: invalidate cached blocks when freeing them

Darrick J. Wong
2025-05-22T00:09:17Z

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 | 6 +++++-
debian/libext2fs2t64.symbols | 1 +
lib/ext2fs/alloc_stats.c | 7 +++++++
lib/ext2fs/io_manager.c | 8 ++++++++
lib/ext2fs/unix_io.c | 32 ++++++++++++++++++++++++++++++++
5 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/lib/ext2fs/ext2_io.h b/lib/ext2fs/ext2_io.h
index 78c988374c8808..bab7f2a6a44b81 100644
--- a/lib/ext2fs/ext2_io.h
+++ b/lib/ext2fs/ext2_io.h
@@ -103,7 +103,9 @@ 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_blk)(io_channel channel,
+ unsigned long long block);
+ long reserved[12];
};

#define IO_FLAG_RW 0x0001
@@ -147,6 +149,8 @@ extern errcode_t io_channel_cache_readahead(io_channel io,
unsigned long long block,
unsigned long long count);
extern errcode_t io_channel_fd(io_channel io, int *fd);
+extern errcode_t io_channel_invalidate_blk(io_channel io,
+ unsigned long long block);

#ifdef _WIN32
/* windows_io.c */
diff --git a/debian/libext2fs2t64.symbols b/debian/libext2fs2t64.symbols
index 9cf3b33ca15f91..13870c4b545b2f 100644
--- a/debian/libext2fs2t64.symbols
+++ b/debian/libext2fs2t64.symbols
@@ -689,6 +689,7 @@ libext2fs.so.2 libext2fs2t64 #MINVER#
io_channel_cache_readahead@Base 1.43
io_channel_discard@Base 1.42
io_channel_fd@Base 1.47.3
+ io_channel_invalidate_blk@Base 1.47.3
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 6f98bcc7cbd5f3..4aeaa286b88a7e 100644
--- a/lib/ext2fs/alloc_stats.c
+++ b/lib/ext2fs/alloc_stats.c
@@ -84,6 +84,13 @@ void ext2fs_block_alloc_stats2(ext2_filsys fs, blk64_t blk, int inuse)
ext2fs_mark_bb_dirty(fs);
if (fs->block_alloc_stats)
(fs->block_alloc_stats)(fs, (blk64_t) blk, inuse);
+
+ if (inuse < 0) {
+ unsigned int i;
+
+ for (i = 0; i < EXT2FS_CLUSTER_RATIO(fs); i++)
+ io_channel_invalidate_blk(fs->io, blk + i);
+ }
}

void ext2fs_block_alloc_stats(ext2_filsys fs, blk_t blk, int inuse)
diff --git a/lib/ext2fs/io_manager.c b/lib/ext2fs/io_manager.c
index 1bab069de63e12..aa7fc58b846be8 100644
--- a/lib/ext2fs/io_manager.c
+++ b/lib/ext2fs/io_manager.c
@@ -158,3 +158,11 @@ errcode_t io_channel_fd(io_channel io, int *fd)

return io->manager->get_fd(io, fd);
}
+
+errcode_t io_channel_invalidate_blk(io_channel io, unsigned long long block)
+{
+ if (!io->manager->invalidate_blk)
+ return EXT2_ET_OP_NOT_SUPPORTED;
+
+ return io->manager->invalidate_blk(io, block);
+}
diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index 0fc83e471ca0fe..89f7915371307f 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -664,6 +664,23 @@ static errcode_t reuse_cache(io_channel channel,
#define FLUSH_INVALIDATE 0x01
#define FLUSH_NOLOCK 0x02

+/* Remove a block from the cache. Dirty contents are discarded. */
+static void invalidate_cached_block(io_channel channel,
+ struct unix_private_data *data,
+ unsigned long long block)
+{
+ 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)
+ continue;
+ cache->in_use = 0;
+ }
+ mutex_unlock(data, CACHE_MTX);
+}
+
/*
* Flush all of the blocks in the cache
*/
@@ -1705,6 +1722,19 @@ static errcode_t unix_get_fd(io_channel channel, int *fd)
return 0;
}

+static errcode_t unix_invalidate_blk(io_channel channel,
+ unsigned long long block)
+{
+ 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_block(channel, data, block);
+ return 0;
+}
+
#if __GNUC_PREREQ (4, 6)
#pragma GCC diagnostic pop
#endif
@@ -1727,6 +1757,7 @@ static struct struct_io_manager struct_unix_manager = {
.cache_readahead = unix_cache_readahead,
.zeroout = unix_zeroout,
.get_fd = unix_get_fd,
+ .invalidate_blk = unix_invalidate_blk,
};

io_manager unix_io_manager = &struct_unix_manager;
@@ -1749,6 +1780,7 @@ static struct struct_io_manager struct_unixfd_manager = {
.cache_readahead = unix_cache_readahead,
.zeroout = unix_zeroout,
.get_fd = unix_get_fd,
+ .invalidate_blk = unix_invalidate_blk,
};

io_manager unixfd_io_manager = &struct_unixfd_manager;