* [PATCH v3 3/5] btrfs-progs: implement the missing btrfs_insert_hole_extent()
2026-04-09 4:31 [PATCH v3 0/5] btrfs-progs: mkfs/rootdir: cleanup and test case enhancement Qu Wenruo
2026-04-09 4:31 ` [PATCH v3 1/5] btrfs-progs: mkfs-tests: also test hole-deteciton without no-holes Qu Wenruo
2026-04-09 4:31 ` [PATCH v3 2/5] btrfs-progs: mkfs-tests: add a test case to verify the content of rootdir Qu Wenruo
@ 2026-04-09 4:31 ` Qu Wenruo
2026-04-09 4:31 ` [PATCH v3 4/5] btrfs-progs: mkfs/rootdir: extract compressed write path Qu Wenruo
2026-04-09 4:31 ` [PATCH v3 5/5] btrfs-progs: mkfs/rootdir: use st_blocks for size estimation Qu Wenruo
4 siblings, 0 replies; 6+ messages in thread
From: Qu Wenruo @ 2026-04-09 4:31 UTC (permalink / raw)
To: linux-btrfs
Commit f8efe9f724c0 ("btrfs-progs: sync file-item.h into progs")
introduce the definition of btrfs_insert_hole_extent() but without an
implementation.
Now there are several call sites implementing a simple wrapper to insert
a hole extent. It's time to implement that function, which is pretty
simple, just set the file extent type to REG and set
disk_num_bytes/disk_bytenr to 0 with proper ram_bytes/num_bytes.
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
kernel-shared/file-item.c | 17 +++++++++++++++++
kernel-shared/file.c | 6 +-----
mkfs/rootdir.c | 8 ++------
3 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/kernel-shared/file-item.c b/kernel-shared/file-item.c
index c6cd3ce51124..76d6bfdb6824 100644
--- a/kernel-shared/file-item.c
+++ b/kernel-shared/file-item.c
@@ -25,6 +25,23 @@
#include "kernel-shared/file-item.h"
#include "kernel-shared/extent_io.h"
#include "common/internal.h"
+#include "common/messages.h"
+
+int btrfs_insert_hole_extent(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, u64 objectid, u64 pos,
+ u64 num_bytes)
+{
+ struct btrfs_file_extent_item stack_fi = { 0 };
+ const u32 blocksize = root->fs_info->sectorsize;
+
+ UASSERT(IS_ALIGNED(pos, blocksize));
+ UASSERT(IS_ALIGNED(num_bytes, blocksize));
+
+ btrfs_set_stack_file_extent_type(&stack_fi, BTRFS_FILE_EXTENT_REG);
+ btrfs_set_stack_file_extent_num_bytes(&stack_fi, num_bytes);
+ btrfs_set_stack_file_extent_ram_bytes(&stack_fi, num_bytes);
+ return btrfs_insert_file_extent(trans, root, objectid, pos, &stack_fi);
+}
#define MAX_CSUM_ITEMS(r, size) ((((BTRFS_LEAF_DATA_SIZE(r->fs_info) - \
sizeof(struct btrfs_item) * 2) / \
diff --git a/kernel-shared/file.c b/kernel-shared/file.c
index 12cd50e796b9..546e161abfdb 100644
--- a/kernel-shared/file.c
+++ b/kernel-shared/file.c
@@ -150,7 +150,6 @@ int btrfs_punch_hole(struct btrfs_trans_handle *trans,
u64 ino, u64 offset, u64 len)
{
struct btrfs_path *path;
- struct btrfs_file_extent_item stack_fi = { 0 };
int ret = 0;
path = btrfs_alloc_path();
@@ -165,10 +164,7 @@ int btrfs_punch_hole(struct btrfs_trans_handle *trans,
goto out;
}
- btrfs_set_stack_file_extent_type(&stack_fi, BTRFS_FILE_EXTENT_REG);
- btrfs_set_stack_file_extent_num_bytes(&stack_fi, len);
- btrfs_set_stack_file_extent_ram_bytes(&stack_fi, len);
- ret = btrfs_insert_file_extent(trans, root, ino, offset, &stack_fi);
+ ret = btrfs_insert_hole_extent(trans, root, ino, offset, len);
out:
btrfs_free_path(path);
return ret;
diff --git a/mkfs/rootdir.c b/mkfs/rootdir.c
index 37191ee427b7..62f7c57c5e4a 100644
--- a/mkfs/rootdir.c
+++ b/mkfs/rootdir.c
@@ -411,8 +411,7 @@ static int insert_reserved_file_extent(struct btrfs_trans_handle *trans,
* hole. And hole extent has no size limit, no need to loop.
*/
if (disk_bytenr == 0)
- return btrfs_insert_file_extent(trans, root, ino,
- file_pos, stack_fi);
+ return btrfs_insert_hole_extent(trans, root, ino, file_pos, num_bytes);
path = btrfs_alloc_path();
if (!path)
@@ -819,10 +818,7 @@ static int add_file_item_extent(struct btrfs_trans_handle *trans,
*/
const u64 length = min_t(u64, next - file_pos, SZ_1G);
- btrfs_set_stack_file_extent_type(&stack_fi, BTRFS_FILE_EXTENT_REG);
- btrfs_set_stack_file_extent_num_bytes(&stack_fi, length);
- btrfs_set_stack_file_extent_ram_bytes(&stack_fi, length);
- ret = btrfs_insert_file_extent(trans, root, objectid, file_pos, &stack_fi);
+ ret = btrfs_insert_hole_extent(trans, root, objectid, file_pos, length);
if (ret < 0) {
error("cannot insert hole for range [%llu, %llu)",
file_pos, file_pos + length);
--
2.53.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH v3 4/5] btrfs-progs: mkfs/rootdir: extract compressed write path
2026-04-09 4:31 [PATCH v3 0/5] btrfs-progs: mkfs/rootdir: cleanup and test case enhancement Qu Wenruo
` (2 preceding siblings ...)
2026-04-09 4:31 ` [PATCH v3 3/5] btrfs-progs: implement the missing btrfs_insert_hole_extent() Qu Wenruo
@ 2026-04-09 4:31 ` Qu Wenruo
2026-04-09 4:31 ` [PATCH v3 5/5] btrfs-progs: mkfs/rootdir: use st_blocks for size estimation Qu Wenruo
4 siblings, 0 replies; 6+ messages in thread
From: Qu Wenruo @ 2026-04-09 4:31 UTC (permalink / raw)
To: linux-btrfs
Currently add_file_item_extent() have several different
optimizations/handlings:
- Hole detection
Which happens before any writes.
Thus brings the minimal impact to the remaining methods.
- Compressed write
- Reflink from source fs
- Regular read/writes
The last 3 share the same extent reservation, but with quite some extra
handling.
E.g. for compressed writes if the compression failed, we need to reset
the buffer size and fallback to regular read/writes.
This makes the code much harder to read, and the shared code is minimal,
only sharing the same btrfs_reserve_extent() and
insert_reserved_file_extent() calls.
Extract compressed write into its dedicated helper so that the fallback
logic is much easier to understand.
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
mkfs/rootdir.c | 249 ++++++++++++++++++++++++++++---------------------
1 file changed, 141 insertions(+), 108 deletions(-)
diff --git a/mkfs/rootdir.c b/mkfs/rootdir.c
index 62f7c57c5e4a..5c0bc012a354 100644
--- a/mkfs/rootdir.c
+++ b/mkfs/rootdir.c
@@ -779,6 +779,125 @@ static int do_reflink_write(struct btrfs_fs_info *info,
return 0;
}
+static s32 read_from_source(const struct btrfs_fs_info *fs_info,
+ const char *path, int fd,
+ char *buf, u64 filepos, u32 length)
+{
+ u32 cur = 0;
+
+ UASSERT(IS_ALIGNED(filepos, fs_info->sectorsize));
+ UASSERT(length <= MAX_EXTENT_SIZE);
+
+ while (cur < length) {
+ ssize_t ret;
+
+ ret = pread(fd, buf + cur, length - cur, filepos + cur);
+ if (ret < 0) {
+ error("cannot read %s at offset %llu length %u: %m",
+ path, filepos + cur, length - cur);
+ return -errno;
+ }
+ cur += ret;
+ }
+ return length;
+}
+
+/*
+ * Return >0 for the number of bytes read from @source and submitted as
+ * compressed write.
+ * Return <0 for errors, including non-fatal ones, e.g. -E2BIG if compression
+ * ratio is bad.
+ */
+static int try_compressed_write(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_inode_item *btrfs_inode,
+ u64 objectid,
+ const struct source_descriptor *source,
+ u64 filepos, u32 length)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_file_extent_item stack_fi = { 0 };
+ struct btrfs_key key;
+ const u32 blocksize = fs_info->sectorsize;
+ const bool first_sector = !(btrfs_stack_inode_flags(btrfs_inode) &
+ BTRFS_INODE_COMPRESS);
+ u64 inode_flags = btrfs_stack_inode_flags(btrfs_inode);
+ u64 sb_flags = btrfs_super_incompat_flags(fs_info->super_copy);
+ u32 to_write;
+ ssize_t comp_ret;
+ int ret;
+
+ UASSERT(length > 0);
+ length = min_t(u32, length, BTRFS_MAX_COMPRESSED);
+ if (length <= root->fs_info->sectorsize)
+ return -E2BIG;
+ ret = read_from_source(root->fs_info, source->path_name, source->fd,
+ source->buf, filepos, length);
+ if (ret < 0)
+ return ret;
+ switch (g_compression) {
+ case BTRFS_COMPRESS_ZLIB:
+ comp_ret = zlib_compress_extent(first_sector, blocksize,
+ source->buf, length,
+ source->comp_buf);
+ break;
+#if COMPRESSION_LZO
+ case BTRFS_COMPRESS_LZO:
+ sb_flags |= BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO;
+ comp_ret = lzo_compress_extent(blocksize, source->buf,
+ length, source->comp_buf,
+ source->wrkmem);
+ break;
+#endif
+#if COMPRESSION_ZSTD
+ case BTRFS_COMPRESS_ZSTD:
+ sb_flags |= BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD;
+ comp_ret = zstd_compress_extent(first_sector, blocksize,
+ source->buf, length,
+ source->comp_buf);
+ break;
+#endif
+ default:
+ comp_ret = -EINVAL;
+ break;
+ }
+ if (comp_ret < 0)
+ return comp_ret;
+
+ to_write = round_up(comp_ret, blocksize);
+ memset(source->comp_buf + comp_ret, 0, to_write - comp_ret);
+ inode_flags |= BTRFS_INODE_COMPRESS;
+ btrfs_set_stack_inode_flags(btrfs_inode, inode_flags);
+ btrfs_set_super_incompat_flags(fs_info->super_copy, sb_flags);
+
+ ret = btrfs_reserve_extent(trans, root, to_write, 0, 0, (u64)-1, &key, 1);
+ if (ret < 0)
+ return ret;
+ ret = write_data_to_disk(fs_info, source->comp_buf, key.objectid, to_write);
+ if (ret < 0)
+ return ret;
+ for (unsigned int i = 0; i < to_write / blocksize; i++) {
+ ret = btrfs_csum_file_block(trans, key.objectid + (i * blocksize),
+ BTRFS_EXTENT_CSUM_OBJECTID,
+ root->fs_info->csum_type,
+ source->comp_buf + (i * blocksize));
+ if (ret)
+ return ret;
+ }
+ btrfs_set_stack_file_extent_type(&stack_fi, BTRFS_FILE_EXTENT_REG);
+ btrfs_set_stack_file_extent_disk_bytenr(&stack_fi, key.objectid);
+ btrfs_set_stack_file_extent_disk_num_bytes(&stack_fi, to_write);
+ btrfs_set_stack_file_extent_num_bytes(&stack_fi, round_up(length, blocksize));
+ btrfs_set_stack_file_extent_ram_bytes(&stack_fi, round_up(length, blocksize));
+ btrfs_set_stack_file_extent_compression(&stack_fi, g_compression);
+
+ ret = insert_reserved_file_extent(trans, root, objectid, btrfs_inode,
+ filepos, &stack_fi);
+ if (ret < 0)
+ return ret;
+ return length;
+}
+
static int add_file_item_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_inode_item *btrfs_inode,
@@ -788,14 +907,13 @@ static int add_file_item_extent(struct btrfs_trans_handle *trans,
{
int ret;
u32 sectorsize = root->fs_info->sectorsize;
- u64 bytes_read, first_block, to_read, to_write;
+ u64 first_block, to_read, to_write;
struct btrfs_key key;
struct btrfs_file_extent_item stack_fi = { 0 };
u64 buf_size;
char *write_buf;
bool do_comp = g_compression != BTRFS_COMPRESS_NONE;
bool datasum = true;
- ssize_t comp_ret;
u64 flags = btrfs_stack_inode_flags(btrfs_inode);
off_t next;
@@ -835,120 +953,35 @@ static int add_file_item_extent(struct btrfs_trans_handle *trans,
if (next == (off_t)-1 || !IS_ALIGNED(next, sectorsize) || next > source->size)
next = source->size;
- buf_size = do_comp ? BTRFS_MAX_COMPRESSED : MAX_EXTENT_SIZE;
- to_read = min_t(u64, file_pos + buf_size, next) - file_pos;
- bytes_read = 0;
-
- while (bytes_read < to_read) {
- ssize_t ret_read;
-
- ret_read = pread(source->fd, source->buf + bytes_read,
- to_read - bytes_read, file_pos + bytes_read);
- if (ret_read < 0) {
- error("cannot read %s at offset %llu length %llu: %m",
- source->path_name, file_pos + bytes_read,
- to_read - bytes_read);
- return -errno;
- }
-
- bytes_read += ret_read;
- }
-
- if (bytes_read <= sectorsize)
- do_comp = false;
-
- if (do_comp) {
- bool first_sector = !(flags & BTRFS_INODE_COMPRESS);
-
- switch (g_compression) {
- case BTRFS_COMPRESS_ZLIB:
- comp_ret = zlib_compress_extent(first_sector, sectorsize,
- source->buf, bytes_read,
- source->comp_buf);
- break;
-#if COMPRESSION_LZO
- case BTRFS_COMPRESS_LZO:
- comp_ret = lzo_compress_extent(sectorsize, source->buf,
- bytes_read,
- source->comp_buf,
- source->wrkmem);
- break;
-#endif
-#if COMPRESSION_ZSTD
- case BTRFS_COMPRESS_ZSTD:
- comp_ret = zstd_compress_extent(first_sector, sectorsize,
- source->buf, bytes_read,
- source->comp_buf);
- break;
-#endif
- default:
- comp_ret = -EINVAL;
- break;
- }
-
+ if (do_comp && next - file_pos > sectorsize) {
+ ret = try_compressed_write(trans, root, btrfs_inode, objectid,
+ source, file_pos, next - file_pos);
+ if (ret > 0)
+ return ret;
+ if (ret < 0 && ret != -E2BIG)
+ return ret;
/*
- * If the function returned -E2BIG, the extent is incompressible.
- * If this is the first sector, add the nocompress flag,
- * increase the buffer size, and read the rest of the extent.
+ * If the inode doesn't have INODE_COMPRESS flag set, it means
+ * the compression failed at the first block.
+ * Set the NOCOMPRESS flag indicating bad compression ratio.
*/
- if (comp_ret == -E2BIG)
- do_comp = false;
- else if (comp_ret < 0)
- return comp_ret;
-
- if (comp_ret == -E2BIG && first_sector) {
+ if (!(btrfs_stack_inode_flags(btrfs_inode) & BTRFS_INODE_COMPRESS)) {
flags |= BTRFS_INODE_NOCOMPRESS;
btrfs_set_stack_inode_flags(btrfs_inode, flags);
-
- buf_size = MAX_EXTENT_SIZE;
- to_read = min_t(u64, file_pos + buf_size, next) - file_pos;
-
- while (bytes_read < to_read) {
- ssize_t ret_read;
-
- ret_read = pread(source->fd,
- source->buf + bytes_read,
- to_read - bytes_read,
- file_pos + bytes_read);
- if (ret_read < 0) {
- error("cannot read %s at offset %llu length %llu: %m",
- source->path_name,
- file_pos + bytes_read,
- to_read - bytes_read);
- return -errno;
- }
-
- bytes_read += ret_read;
- }
}
+ /* Fallback to other methods. */
}
- if (do_comp) {
- u64 features;
+ buf_size = MAX_EXTENT_SIZE;
+ to_read = min_t(u64, file_pos + buf_size, next) - file_pos;
+ ret = read_from_source(root->fs_info, source->path_name, source->fd,
+ source->buf, file_pos, to_read);
+ if (ret < 0)
+ return ret;
- to_write = round_up(comp_ret, sectorsize);
- write_buf = source->comp_buf;
- memset(write_buf + comp_ret, 0, to_write - comp_ret);
-
- flags |= BTRFS_INODE_COMPRESS;
- btrfs_set_stack_inode_flags(btrfs_inode, flags);
-
- if (g_compression == BTRFS_COMPRESS_ZSTD) {
- features = btrfs_super_incompat_flags(trans->fs_info->super_copy);
- features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD;
- btrfs_set_super_incompat_flags(trans->fs_info->super_copy,
- features);
- } else if (g_compression == BTRFS_COMPRESS_LZO) {
- features = btrfs_super_incompat_flags(trans->fs_info->super_copy);
- features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO;
- btrfs_set_super_incompat_flags(trans->fs_info->super_copy,
- features);
- }
- } else {
- to_write = round_up(to_read, sectorsize);
- write_buf = source->buf;
- memset(write_buf + to_read, 0, to_write - to_read);
- }
+ to_write = round_up(to_read, sectorsize);
+ write_buf = source->buf;
+ memset(write_buf + to_read, 0, to_write - to_read);
ret = btrfs_reserve_extent(trans, root, to_write, 0, 0,
(u64)-1, &key, 1);
--
2.53.0
^ permalink raw reply related [flat|nested] 6+ messages in thread