Added inline_max, to optionally limit the size of inlined files

Inlined files live in metadata and decrease storage requirements, but
may be limited to improve metadata-related performance. This is
especially important given the current plague of metadata performance.

Though decreasing inline_max may make metadata more dense and increase
block usage, so it's important to benchmark if optimizing for speed.

The underlying limits of inlined files haven't changed:
1. Inlined files need to fit in RAM, so <= cache_size
2. Inlined files need to fit in a single attr, so <= attr_max
3. Inlined files need to fit in 1/8 of a block to avoid metadata
   overflow issues, this is after limiting by metadata_max,
   so <= min(metadata_max, block_size)/8

By default, the largest possible inline_max is used. This preserves
backwards compatibility and is probably a good default for most use
cases.

This does have the awkward effect of requiring inline_max=-1 to
indicate disabled inlined files, but I don't think there's a good
way around this.

lfs.c

@@ -3524,11 +3524,7 @@ static lfs_ssize_t lfs_file_flushedwrite(lfs_t *lfs, lfs_file_t *file,
     lfs_size_t nsize = size;
 
     if ((file->flags & LFS_F_INLINE) &&
-            lfs_max(file->pos+nsize, file->ctz.size) >
+            lfs_max(file->pos+nsize, file->ctz.size) > lfs->inline_max) {
-            lfs_min(0x3fe, lfs_min(
-                lfs->cfg->cache_size,
-                (lfs->cfg->metadata_max ?
-                    lfs->cfg->metadata_max : lfs->cfg->block_size) / 8))) {
         // inline file doesn't fit anymore
         int err = lfs_file_outline(lfs, file);
         if (err) {
@@ -3725,10 +3721,7 @@ static int lfs_file_rawtruncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size) {
     lfs_off_t oldsize = lfs_file_rawsize(lfs, file);
     if (size < oldsize) {
         // revert to inline file?
-        if (size <= lfs_min(0x3fe, lfs_min(
+        if (size <= lfs->inline_max) {
-                lfs->cfg->cache_size,
-                (lfs->cfg->metadata_max ?
-                    lfs->cfg->metadata_max : lfs->cfg->block_size) / 8))) {
             // flush+seek to head
             lfs_soff_t res = lfs_file_rawseek(lfs, file, 0, LFS_SEEK_SET);
             if (res < 0) {
@@ -4259,6 +4252,27 @@ static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
 
     LFS_ASSERT(lfs->cfg->metadata_max <= lfs->cfg->block_size);
 
+    LFS_ASSERT(lfs->cfg->inline_max == (lfs_size_t)-1
+            || lfs->cfg->inline_max <= lfs->cfg->cache_size);
+    LFS_ASSERT(lfs->cfg->inline_max == (lfs_size_t)-1
+            || lfs->cfg->inline_max <= lfs->attr_max);
+    LFS_ASSERT(lfs->cfg->inline_max == (lfs_size_t)-1
+            || lfs->cfg->inline_max <= ((lfs->cfg->metadata_max)
+                ? lfs->cfg->metadata_max
+                : lfs->cfg->block_size)/8);
+    lfs->inline_max = lfs->cfg->inline_max;
+    if (lfs->inline_max == (lfs_size_t)-1) {
+        lfs->inline_max = 0;
+    } else if (lfs->inline_max == 0) {
+        lfs->inline_max = lfs_min(
+                lfs->cfg->cache_size,
+                lfs_min(
+                    lfs->attr_max,
+                    ((lfs->cfg->metadata_max)
+                        ? lfs->cfg->metadata_max
+                        : lfs->cfg->block_size)/8));
+    }
+
     // setup default state
     lfs->root[0] = LFS_BLOCK_NULL;
     lfs->root[1] = LFS_BLOCK_NULL;
@@ -4482,6 +4496,9 @@ static int lfs_rawmount(lfs_t *lfs, const struct lfs_config *cfg) {
                 }
 
                 lfs->attr_max = superblock.attr_max;
+
+                // we also need to update inline_max in case attr_max changed
+                lfs->inline_max = lfs_min(lfs->inline_max, lfs->attr_max);
             }
 
             // this is where we get the block_count from disk if block_count=0

lfs.h

@@ -272,6 +272,15 @@ struct lfs_config {
     // Defaults to block_size when zero.
     lfs_size_t metadata_max;
 
+    // Optional upper limit on inlined files in bytes. Inlined files live in
+    // metadata and decrease storage requirements, but may be limited to
+    // improve metadata-related performance. Must be <= cache_size, <=
+    // attr_max, and <= block_size/8. Defaults to the largest possible
+    // inline_max when zero.
+    //
+    // Set to -1 to disable inlined files.
+    lfs_size_t inline_max;
+
 #ifdef LFS_MULTIVERSION
     // On-disk version to use when writing in the form of 16-bit major version
     // + 16-bit minor version. This limiting metadata to what is supported by
@@ -451,6 +460,7 @@ typedef struct lfs {
     lfs_size_t name_max;
     lfs_size_t file_max;
     lfs_size_t attr_max;
+    lfs_size_t inline_max;
 
 #ifdef LFS_MIGRATE
     struct lfs1 *lfs1;

runners/bench_runner.c

@@ -1322,6 +1322,7 @@ void perm_run(
         .cache_size         = CACHE_SIZE,
         .lookahead_size     = LOOKAHEAD_SIZE,
         .compact_thresh     = COMPACT_THRESH,
+        .inline_max         = INLINE_MAX,
     };
 
     struct lfs_emubd_config bdcfg = {

runners/bench_runner.h

@@ -96,11 +96,12 @@ intmax_t bench_define(size_t define);
 #define CACHE_SIZE_i         6
 #define LOOKAHEAD_SIZE_i     7
 #define COMPACT_THRESH_i     8
-#define BLOCK_CYCLES_i       9
+#define INLINE_MAX_i         9
-#define ERASE_VALUE_i        10
+#define BLOCK_CYCLES_i       10
-#define ERASE_CYCLES_i       11
+#define ERASE_VALUE_i        11
-#define BADBLOCK_BEHAVIOR_i  12
+#define ERASE_CYCLES_i       12
-#define POWERLOSS_BEHAVIOR_i 13
+#define BADBLOCK_BEHAVIOR_i  13
+#define POWERLOSS_BEHAVIOR_i 14
 
 #define READ_SIZE           bench_define(READ_SIZE_i)
 #define PROG_SIZE           bench_define(PROG_SIZE_i)
@@ -111,6 +112,7 @@ intmax_t bench_define(size_t define);
 #define CACHE_SIZE          bench_define(CACHE_SIZE_i)
 #define LOOKAHEAD_SIZE      bench_define(LOOKAHEAD_SIZE_i)
 #define COMPACT_THRESH      bench_define(COMPACT_THRESH_i)
+#define INLINE_MAX          bench_define(INLINE_MAX_i)
 #define BLOCK_CYCLES        bench_define(BLOCK_CYCLES_i)
 #define ERASE_VALUE         bench_define(ERASE_VALUE_i)
 #define ERASE_CYCLES        bench_define(ERASE_CYCLES_i)
@@ -127,6 +129,7 @@ intmax_t bench_define(size_t define);
     BENCH_DEF(CACHE_SIZE,         lfs_max(64,lfs_max(READ_SIZE,PROG_SIZE))) \
     BENCH_DEF(LOOKAHEAD_SIZE,     16) \
     BENCH_DEF(COMPACT_THRESH,     0) \
+    BENCH_DEF(INLINE_MAX,         0) \
     BENCH_DEF(BLOCK_CYCLES,       -1) \
     BENCH_DEF(ERASE_VALUE,        0xff) \
     BENCH_DEF(ERASE_CYCLES,       0) \
@@ -134,7 +137,7 @@ intmax_t bench_define(size_t define);
     BENCH_DEF(POWERLOSS_BEHAVIOR, LFS_EMUBD_POWERLOSS_NOOP)
 
 #define BENCH_GEOMETRY_DEFINE_COUNT 4
-#define BENCH_IMPLICIT_DEFINE_COUNT 14
+#define BENCH_IMPLICIT_DEFINE_COUNT 15
 
 
 #endif

runners/test_runner.c

@@ -1347,6 +1347,7 @@ static void run_powerloss_none(
         .cache_size         = CACHE_SIZE,
         .lookahead_size     = LOOKAHEAD_SIZE,
         .compact_thresh     = COMPACT_THRESH,
+        .inline_max         = INLINE_MAX,
     #ifdef LFS_MULTIVERSION
         .disk_version       = DISK_VERSION,
     #endif
@@ -1424,6 +1425,7 @@ static void run_powerloss_linear(
         .cache_size         = CACHE_SIZE,
         .lookahead_size     = LOOKAHEAD_SIZE,
         .compact_thresh     = COMPACT_THRESH,
+        .inline_max         = INLINE_MAX,
     #ifdef LFS_MULTIVERSION
         .disk_version       = DISK_VERSION,
     #endif
@@ -1518,6 +1520,7 @@ static void run_powerloss_log(
         .cache_size         = CACHE_SIZE,
         .lookahead_size     = LOOKAHEAD_SIZE,
         .compact_thresh     = COMPACT_THRESH,
+        .inline_max         = INLINE_MAX,
     #ifdef LFS_MULTIVERSION
         .disk_version       = DISK_VERSION,
     #endif
@@ -1610,6 +1613,7 @@ static void run_powerloss_cycles(
         .cache_size         = CACHE_SIZE,
         .lookahead_size     = LOOKAHEAD_SIZE,
         .compact_thresh     = COMPACT_THRESH,
+        .inline_max         = INLINE_MAX,
     #ifdef LFS_MULTIVERSION
         .disk_version       = DISK_VERSION,
     #endif
@@ -1800,6 +1804,7 @@ static void run_powerloss_exhaustive(
         .cache_size         = CACHE_SIZE,
         .lookahead_size     = LOOKAHEAD_SIZE,
         .compact_thresh     = COMPACT_THRESH,
+        .inline_max         = INLINE_MAX,
     #ifdef LFS_MULTIVERSION
         .disk_version       = DISK_VERSION,
     #endif

runners/test_runner.h

@@ -89,12 +89,13 @@ intmax_t test_define(size_t define);
 #define CACHE_SIZE_i         6
 #define LOOKAHEAD_SIZE_i     7
 #define COMPACT_THRESH_i     8
-#define BLOCK_CYCLES_i       9
+#define INLINE_MAX_i         9
-#define ERASE_VALUE_i        10
+#define BLOCK_CYCLES_i       10
-#define ERASE_CYCLES_i       11
+#define ERASE_VALUE_i        11
-#define BADBLOCK_BEHAVIOR_i  12
+#define ERASE_CYCLES_i       12
-#define POWERLOSS_BEHAVIOR_i 13
+#define BADBLOCK_BEHAVIOR_i  13
-#define DISK_VERSION_i       14
+#define POWERLOSS_BEHAVIOR_i 14
+#define DISK_VERSION_i       15
 
 #define READ_SIZE           TEST_DEFINE(READ_SIZE_i)
 #define PROG_SIZE           TEST_DEFINE(PROG_SIZE_i)
@@ -105,6 +106,7 @@ intmax_t test_define(size_t define);
 #define CACHE_SIZE          TEST_DEFINE(CACHE_SIZE_i)
 #define LOOKAHEAD_SIZE      TEST_DEFINE(LOOKAHEAD_SIZE_i)
 #define COMPACT_THRESH      TEST_DEFINE(COMPACT_THRESH_i)
+#define INLINE_MAX          TEST_DEFINE(INLINE_MAX_i)
 #define BLOCK_CYCLES        TEST_DEFINE(BLOCK_CYCLES_i)
 #define ERASE_VALUE         TEST_DEFINE(ERASE_VALUE_i)
 #define ERASE_CYCLES        TEST_DEFINE(ERASE_CYCLES_i)
@@ -122,6 +124,7 @@ intmax_t test_define(size_t define);
     TEST_DEF(CACHE_SIZE,         lfs_max(64,lfs_max(READ_SIZE,PROG_SIZE))) \
     TEST_DEF(LOOKAHEAD_SIZE,     16) \
     TEST_DEF(COMPACT_THRESH,     0) \
+    TEST_DEF(INLINE_MAX,         0) \
     TEST_DEF(BLOCK_CYCLES,       -1) \
     TEST_DEF(ERASE_VALUE,        0xff) \
     TEST_DEF(ERASE_CYCLES,       0) \
@@ -130,7 +133,7 @@ intmax_t test_define(size_t define);
     TEST_DEF(DISK_VERSION,       0)
 
 #define TEST_GEOMETRY_DEFINE_COUNT 4
-#define TEST_IMPLICIT_DEFINE_COUNT 15
+#define TEST_IMPLICIT_DEFINE_COUNT 16
 
 
 #endif

tests/test_files.toml

@@ -1,5 +1,6 @@
 
 [cases.test_files_simple]
+defines.INLINE_MAX = [0, -1, 8]
 code = '''
     lfs_t lfs;
     lfs_format(&lfs, cfg) => 0;
@@ -25,6 +26,7 @@ code = '''
 [cases.test_files_large]
 defines.SIZE = [32, 8192, 262144, 0, 7, 8193]
 defines.CHUNKSIZE = [31, 16, 33, 1, 1023]
+defines.INLINE_MAX = [0, -1, 8]
 code = '''
     lfs_t lfs;
     lfs_format(&lfs, cfg) => 0;
@@ -67,6 +69,7 @@ code = '''
 defines.SIZE1 = [32, 8192, 131072, 0, 7, 8193]
 defines.SIZE2 = [32, 8192, 131072, 0, 7, 8193]
 defines.CHUNKSIZE = [31, 16, 1]
+defines.INLINE_MAX = [0, -1, 8]
 code = '''
     lfs_t lfs;
     lfs_format(&lfs, cfg) => 0;
@@ -152,6 +155,7 @@ code = '''
 defines.SIZE1 = [32, 8192, 131072, 0, 7, 8193]
 defines.SIZE2 = [32, 8192, 131072, 0, 7, 8193]
 defines.CHUNKSIZE = [31, 16, 1]
+defines.INLINE_MAX = [0, -1, 8]
 code = '''
     lfs_t lfs;
     lfs_format(&lfs, cfg) => 0;
@@ -232,6 +236,7 @@ code = '''
 defines.SIZE1 = [32, 8192, 131072, 0, 7, 8193]
 defines.SIZE2 = [32, 8192, 131072, 0, 7, 8193]
 defines.CHUNKSIZE = [31, 16, 1]
+defines.INLINE_MAX = [0, -1, 8]
 code = '''
     lfs_t lfs;
     lfs_format(&lfs, cfg) => 0;
@@ -303,6 +308,7 @@ code = '''
 [cases.test_files_reentrant_write]
 defines.SIZE = [32, 0, 7, 2049]
 defines.CHUNKSIZE = [31, 16, 65]
+defines.INLINE_MAX = [0, -1, 8]
 reentrant = true
 code = '''
     lfs_t lfs;
@@ -354,11 +360,20 @@ code = '''
 [cases.test_files_reentrant_write_sync]
 defines = [
     # append (O(n))
-    {MODE='LFS_O_APPEND',   SIZE=[32, 0, 7, 2049],  CHUNKSIZE=[31, 16, 65]},
+    {MODE='LFS_O_APPEND',
+        SIZE=[32, 0, 7, 2049],
+        CHUNKSIZE=[31, 16, 65],
+        INLINE_MAX=[0, -1, 8]},
     # truncate (O(n^2))
-    {MODE='LFS_O_TRUNC',    SIZE=[32, 0, 7, 200],   CHUNKSIZE=[31, 16, 65]},
+    {MODE='LFS_O_TRUNC',
+        SIZE=[32, 0, 7, 200],
+        CHUNKSIZE=[31, 16, 65],
+        INLINE_MAX=[0, -1, 8]},
     # rewrite (O(n^2))
-    {MODE=0,                SIZE=[32, 0, 7, 200],   CHUNKSIZE=[31, 16, 65]},
+    {MODE=0,
+        SIZE=[32, 0, 7, 200],
+        CHUNKSIZE=[31, 16, 65],
+        INLINE_MAX=[0, -1, 8]},
 ]
 reentrant = true
 code = '''