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Message-ID: <174553065546.1161238.2653341081512215032.stgit@frogsfrogsfrogs>
Date: Thu, 24 Apr 2025 14:45:59 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: tytso@....edu
Cc: linux-ext4@...r.kernel.org
Subject: [PATCH 2/5] libext2fs: make unix_io cache size configurable
From: Darrick J. Wong <djwong@...nel.org>
Make it so that we can reconfigure the unix IO manager cache size.
fuse2fs might want more than 32 blocks.
Signed-off-by: "Darrick J. Wong" <djwong@...nel.org>
---
lib/ext2fs/unix_io.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 120 insertions(+), 7 deletions(-)
diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index 207a8e63b77fd4..f8be1fe6f8d2c0 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -91,7 +91,7 @@ struct unix_cache {
unsigned write_err:1;
};
-#define CACHE_SIZE 8
+#define DEFAULT_CACHE_SIZE 8
#define WRITE_DIRECT_SIZE 4 /* Must be smaller than CACHE_SIZE */
#define READ_DIRECT_SIZE 4 /* Should be smaller than CACHE_SIZE */
@@ -102,7 +102,8 @@ struct unix_private_data {
int align;
int access_time;
ext2_loff_t offset;
- struct unix_cache cache[CACHE_SIZE];
+ struct unix_cache *cache;
+ unsigned int cache_size;
void *bounce;
struct struct_io_stats io_stats;
#ifdef HAVE_PTHREAD
@@ -476,7 +477,7 @@ static errcode_t alloc_cache(io_channel channel,
int i;
data->access_time = 0;
- for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
+ for (i=0, cache = data->cache; i < data->cache_size; i++, cache++) {
cache->block = 0;
cache->access_time = 0;
cache->dirty = 0;
@@ -502,7 +503,7 @@ static void free_cache(struct unix_private_data *data)
int i;
data->access_time = 0;
- for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
+ for (i=0, cache = data->cache; i < data->cache_size; i++, cache++) {
cache->block = 0;
cache->access_time = 0;
cache->dirty = 0;
@@ -528,7 +529,7 @@ static struct unix_cache *find_cached_block(struct unix_private_data *data,
int i;
unused_cache = oldest_cache = 0;
- for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
+ for (i=0, cache = data->cache; i < data->cache_size; i++, cache++) {
if (!cache->in_use) {
if (!unused_cache)
unused_cache = cache;
@@ -592,7 +593,7 @@ static errcode_t flush_cached_blocks(io_channel channel,
if ((flags & FLUSH_NOLOCK) == 0)
mutex_lock(data, CACHE_MTX);
- for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
+ for (i=0, cache = data->cache; i < data->cache_size; i++, cache++) {
if (!cache->in_use || !cache->dirty)
continue;
retval = raw_write_blk(channel, data,
@@ -616,7 +617,7 @@ static errcode_t flush_cached_blocks(io_channel channel,
if ((flags & FLUSH_NOLOCK) == 0)
mutex_lock(data, CACHE_MTX);
errors_found = 0;
- for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
+ for (i=0, cache = data->cache; i < data->cache_size; i++, cache++) {
if (!cache->in_use || !cache->write_err)
continue;
errors_found = 1;
@@ -648,6 +649,89 @@ static errcode_t flush_cached_blocks(io_channel channel,
}
return retval2;
}
+
+/* Shrink the cache buffers */
+static errcode_t shrink_cache(io_channel channel,
+ struct unix_private_data *data,
+ unsigned int new_size)
+{
+ struct unix_cache *cache, *new_cache;
+ int i;
+ errcode_t retval;
+
+ mutex_lock(data, CACHE_MTX);
+
+ retval = flush_cached_blocks(channel, data,
+ FLUSH_INVALIDATE | FLUSH_NOLOCK);
+ if (retval)
+ goto unlock;
+
+ for (i = new_size, cache = data->cache + new_size;
+ i < data->cache_size;
+ i++, cache++) {
+ cache->block = 0;
+ cache->access_time = 0;
+ cache->dirty = 0;
+ cache->in_use = 0;
+ if (cache->buf)
+ ext2fs_free_mem(&cache->buf);
+ }
+
+ new_cache = realloc(data->cache, new_size * sizeof(struct unix_cache));
+ if (!new_cache) {
+ retval = EXT2_ET_NO_MEMORY;
+ goto unlock;
+ }
+
+ data->cache = new_cache;
+ data->cache_size = new_size;
+
+unlock:
+ mutex_unlock(data, CACHE_MTX);
+ return retval;
+}
+
+/* Grow the cache buffers */
+static errcode_t grow_cache(io_channel channel,
+ struct unix_private_data *data,
+ unsigned int new_size)
+{
+ struct unix_cache *cache, *new_cache;
+ int i;
+ errcode_t retval;
+
+ mutex_lock(data, CACHE_MTX);
+
+ retval = flush_cached_blocks(channel, data,
+ FLUSH_INVALIDATE | FLUSH_NOLOCK);
+ if (retval)
+ goto unlock;
+
+ new_cache = realloc(data->cache, new_size * sizeof(struct unix_cache));
+ if (!new_cache) {
+ retval = EXT2_ET_NO_MEMORY;
+ goto unlock;
+ }
+
+ for (i = data->cache_size, cache = new_cache + data->cache_size;
+ i < new_size;
+ i++, cache++) {
+ cache->block = 0;
+ cache->access_time = 0;
+ cache->dirty = 0;
+ cache->in_use = 0;
+ retval = io_channel_alloc_buf(channel, 0, &cache->buf);
+ if (retval)
+ goto unlock;
+ }
+
+ data->cache = new_cache;
+ data->cache_size = new_size;
+
+unlock:
+ mutex_unlock(data, CACHE_MTX);
+ return retval;
+}
#endif /* NO_IO_CACHE */
#ifdef __linux__
@@ -743,6 +827,13 @@ static errcode_t unix_open_channel(const char *name, int fd,
data->flags = flags;
data->dev = fd;
+ data->cache_size = DEFAULT_CACHE_SIZE;
+ data->cache = calloc(DEFAULT_CACHE_SIZE, sizeof(struct unix_cache));
+ if (!data->cache) {
+ retval = EXT2_ET_NO_MEMORY;
+ goto cleanup;
+ }
+
#if defined(O_DIRECT)
if (flags & IO_FLAG_DIRECT_IO)
io->align = ext2fs_get_dio_alignment(data->dev);
@@ -869,6 +960,8 @@ static errcode_t unix_open_channel(const char *name, int fd,
if (data->dev >= 0)
close(data->dev);
free_cache(data);
+ if (data->cache)
+ free(data->cache);
ext2fs_free_mem(&data);
}
if (io) {
@@ -953,6 +1046,7 @@ static errcode_t unix_close(io_channel channel)
if (close(data->dev) < 0)
retval = errno;
free_cache(data);
+ free(data->cache);
#ifdef HAVE_PTHREAD
if (data->flags & IO_FLAG_THREADS) {
pthread_mutex_destroy(&data->cache_mutex);
@@ -1308,6 +1402,25 @@ static errcode_t unix_set_option(io_channel channel, const char *option,
}
return EXT2_ET_INVALID_ARGUMENT;
}
+#ifndef NO_IO_CACHE
+ if (!strcmp(option, "cache_blocks")) {
+ unsigned long long size;
+
+ if (!arg)
+ return EXT2_ET_INVALID_ARGUMENT;
+
+ errno = 0;
+ size = strtoll(arg, NULL, 0);
+ if (errno || size == 0 || size > INT32_MAX)
+ return EXT2_ET_INVALID_ARGUMENT;
+
+ if (data->cache_size == size)
+ return 0;
+ if (data->cache_size > size)
+ return shrink_cache(channel, data, size);
+ return grow_cache(channel, data, size);
+ }
+#endif
return EXT2_ET_INVALID_ARGUMENT;
}
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