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Subject[RFC v2 72/83] File operation: fallocate.
Date
From: Andiry Xu <jix024@cs.ucsd.edu>

Fallocate works similar as writes, allocating zeroed blocked
for the holes in the request region.

Signed-off-by: Andiry Xu <jix024@cs.ucsd.edu>
---
fs/nova/file.c | 148 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/nova/nova.h | 5 ++
2 files changed, 153 insertions(+)

diff --git a/fs/nova/file.c b/fs/nova/file.c
index b94a9a3..a6b5bd3 100644
--- a/fs/nova/file.c
+++ b/fs/nova/file.c
@@ -113,6 +113,153 @@ static int nova_open(struct inode *inode, struct file *filp)
return generic_file_open(inode, filp);
}

+static long nova_fallocate(struct file *file, int mode, loff_t offset,
+ loff_t len)
+{
+ struct inode *inode = file->f_path.dentry->d_inode;
+ struct super_block *sb = inode->i_sb;
+ struct nova_inode_info *si = NOVA_I(inode);
+ struct nova_inode_info_header *sih = &si->header;
+ struct nova_inode *pi;
+ struct nova_file_write_entry *entry;
+ struct nova_file_write_item *entry_item;
+ struct list_head item_head;
+ struct nova_inode_update update;
+ unsigned long start_blk, num_blocks, ent_blks = 0;
+ unsigned long total_blocks = 0;
+ unsigned long blocknr = 0;
+ unsigned long blockoff;
+ loff_t new_size;
+ long ret = 0;
+ int inplace = 0;
+ int blocksize_mask;
+ int allocated = 0;
+ timing_t fallocate_time;
+ u64 epoch_id;
+ u32 time;
+
+ /*
+ * Fallocate does not make much sence for CoW,
+ * but we still support it for DAX-mmap purpose.
+ */
+
+ /* We only support the FALLOC_FL_KEEP_SIZE mode */
+ if (mode & ~FALLOC_FL_KEEP_SIZE)
+ return -EOPNOTSUPP;
+
+ if (S_ISDIR(inode->i_mode))
+ return -ENODEV;
+
+ INIT_LIST_HEAD(&item_head);
+ new_size = len + offset;
+ if (!(mode & FALLOC_FL_KEEP_SIZE) && new_size > inode->i_size) {
+ ret = inode_newsize_ok(inode, new_size);
+ if (ret)
+ return ret;
+ } else {
+ new_size = inode->i_size;
+ }
+
+ nova_dbgv("%s: inode %lu, offset %lld, count %lld, mode 0x%x\n",
+ __func__, inode->i_ino, offset, len, mode);
+
+ NOVA_START_TIMING(fallocate_t, fallocate_time);
+ inode_lock(inode);
+ sih_lock(sih);
+
+ pi = nova_get_inode(sb, inode);
+ if (!pi) {
+ ret = -EACCES;
+ goto out;
+ }
+
+ inode->i_mtime = inode->i_ctime = current_time(inode);
+ time = current_time(inode).tv_sec;
+
+ blocksize_mask = sb->s_blocksize - 1;
+ start_blk = offset >> sb->s_blocksize_bits;
+ blockoff = offset & blocksize_mask;
+ num_blocks = (blockoff + len + blocksize_mask) >> sb->s_blocksize_bits;
+
+ epoch_id = nova_get_epoch_id(sb);
+ update.tail = sih->log_tail;
+ while (num_blocks > 0) {
+ ent_blks = nova_check_existing_entry(sb, inode, num_blocks,
+ start_blk, &entry,
+ 1, epoch_id, &inplace);
+
+ if (entry && inplace) {
+ if (entry->size < new_size) {
+ /* Update existing entry */
+ entry->size = new_size;
+ nova_persist_entry(entry);
+ }
+ allocated = ent_blks;
+ goto next;
+ }
+
+ /* Allocate zeroed blocks to fill hole */
+ allocated = nova_new_data_blocks(sb, sih, &blocknr, start_blk,
+ ent_blks, ALLOC_INIT_ZERO, ANY_CPU,
+ ALLOC_FROM_HEAD);
+ nova_dbgv("%s: alloc %d blocks @ %lu\n", __func__,
+ allocated, blocknr);
+
+ if (allocated <= 0) {
+ nova_dbg("%s alloc %lu blocks failed!, %d\n",
+ __func__, ent_blks, allocated);
+ ret = allocated;
+ goto out;
+ }
+
+ entry_item = nova_alloc_file_write_item(sb);
+ if (!entry_item) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ /* Handle hole fill write */
+ nova_init_file_write_item(sb, sih, entry_item, epoch_id,
+ start_blk, allocated, blocknr,
+ time, new_size);
+
+ list_add_tail(&entry_item->list, &item_head);
+
+ total_blocks += allocated;
+next:
+ num_blocks -= allocated;
+ start_blk += allocated;
+ }
+
+ ret = nova_commit_writes_to_log(sb, pi, inode,
+ &item_head, total_blocks, 1);
+ if (ret < 0) {
+ nova_err(sb, "commit to log failed\n");
+ goto out;
+ }
+
+ if (ret || (mode & FALLOC_FL_KEEP_SIZE)) {
+ pi->i_flags |= cpu_to_le32(NOVA_EOFBLOCKS_FL);
+ sih->i_flags |= cpu_to_le32(NOVA_EOFBLOCKS_FL);
+ }
+
+ if (!(mode & FALLOC_FL_KEEP_SIZE) && new_size > inode->i_size) {
+ inode->i_size = new_size;
+ sih->i_size = new_size;
+ }
+
+ nova_persist_inode(pi);
+
+out:
+ if (ret < 0)
+ nova_cleanup_incomplete_write(sb, sih, &item_head, 1);
+
+ sih_unlock(sih);
+ inode_unlock(inode);
+ NOVA_END_TIMING(fallocate_t, fallocate_time);
+ return ret;
+}
+
static ssize_t
do_dax_mapping_read(struct file *filp, char __user *buf,
size_t len, loff_t *ppos)
@@ -477,6 +624,7 @@ const struct file_operations nova_dax_file_operations = {
.open = nova_open,
.fsync = nova_fsync,
.flush = nova_flush,
+ .fallocate = nova_fallocate,
};

const struct inode_operations nova_file_inode_operations = {
diff --git a/fs/nova/nova.h b/fs/nova/nova.h
index 6392bb3..ab9e8f3 100644
--- a/fs/nova/nova.h
+++ b/fs/nova/nova.h
@@ -477,6 +477,11 @@ void nova_init_file_write_item(struct super_block *sb,
struct nova_inode_info_header *sih, struct nova_file_write_item *item,
u64 epoch_id, u64 pgoff, int num_pages, u64 blocknr, u32 time,
u64 file_size);
+unsigned long nova_check_existing_entry(struct super_block *sb,
+ struct inode *inode, unsigned long num_blocks, unsigned long start_blk,
+ struct nova_file_write_entry **ret_entry,
+ int check_next, u64 epoch_id,
+ int *inplace);
ssize_t nova_inplace_file_write(struct file *filp, const char __user *buf,
size_t len, loff_t *ppos);
ssize_t do_nova_inplace_file_write(struct file *filp, const char __user *buf,
--
2.7.4
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