[f2fs-dev][PATCH 2/2] f2fs: introduce f2fs_seek_block to support SEEK_{DATA,HOLE} in llseek

Chao Yu
2014-04-22T05:35:07Z

In This patch we introduce f2fs_seek_block to support SEEK_{DATA,HOLE} of
lseek(2).

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
---
fs/f2fs/f2fs.h | 6 ++++
fs/f2fs/file.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 101 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 97da71d..b1d6699 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1074,6 +1074,12 @@ static inline void f2fs_stop_checkpoint(struct f2fs_sb_info *sbi)
((is_inode_flag_set(F2FS_I(i), FI_ACL_MODE)) ? \
(F2FS_I(i)->i_acl_mode) : ((i)->i_mode))

+/* get offset of first page in next direct node */
+#define PGOFS_OF_NEXT_DNODE(pgofs, fi) \
+ ((pgofs < ADDRS_PER_INODE(fi)) ? ADDRS_PER_INODE(fi) : \
+ (pgofs - ADDRS_PER_INODE(fi) + 2 * ADDRS_PER_BLOCK - 1) / \
+ ADDRS_PER_BLOCK * ADDRS_PER_BLOCK + ADDRS_PER_INODE(fi))
+
/*
* file.c
*/
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 60e7d54..da1c3b7 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -194,6 +194,100 @@ out:
return ret;
}

+static loff_t f2fs_seek_block(struct file *file, loff_t offset, int whence)
+{
+ struct inode *inode = file->f_mapping->host;
+ loff_t maxbytes = inode->i_sb->s_maxbytes;
+ struct dnode_of_data dn;
+ pgoff_t pgofs, end_offset, end;
+ loff_t data_ofs = 0, isize;
+ int err = 0;
+
+ mutex_lock(&inode->i_mutex);
+
+ isize = i_size_read(inode);
+ if (offset >= isize)
+ goto fail;
+
+ /* handle inline data case */
+ if (f2fs_has_inline_data(inode)) {
+ if (whence == SEEK_HOLE)
+ data_ofs = isize;
+ goto found;
+ }
+
+ pgofs = (pgoff_t)(offset >> PAGE_CACHE_SHIFT);
+ end = (pgoff_t)(isize >> PAGE_CACHE_SHIFT);
+
+ while (pgofs < end) {
+ set_new_dnode(&dn, inode, NULL, NULL, 0);
+ err = get_dnode_of_data(&dn, pgofs, LOOKUP_NODE_RA);
+ if (err && err != -ENOENT) {
+ goto fail;
+ } else if (err == -ENOENT) {
+ /* direct node is not exist */
+ if (whence == SEEK_DATA) {
+ pgofs = PGOFS_OF_NEXT_DNODE(pgofs,
+ F2FS_I(inode));
+ continue;
+ } else {
+ data_ofs = pgofs << PAGE_CACHE_SHIFT;
+ goto found;
+ }
+ }
+
+ end_offset = IS_INODE(dn.node_page) ?
+ ADDRS_PER_INODE(F2FS_I(inode)) : ADDRS_PER_BLOCK;
+
+ /* find data/hole in dnode block */
+ for (; dn.ofs_in_node < end_offset; dn.ofs_in_node++, pgofs++) {
+ block_t blkaddr;
+ blkaddr = datablock_addr(dn.node_page, dn.ofs_in_node);
+
+ if ((whence == SEEK_DATA && blkaddr != NULL_ADDR) ||
+ (whence == SEEK_HOLE && blkaddr == NULL_ADDR)) {
+ f2fs_put_dnode(&dn);
+ data_ofs = pgofs << PAGE_CACHE_SHIFT;
+ goto found;
+ }
+ }
+ f2fs_put_dnode(&dn);
+ }
+
+ data_ofs = pgofs << PAGE_CACHE_SHIFT;
+ if (data_ofs > isize) {
+ if (whence == SEEK_DATA)
+ goto fail;
+ else
+ data_ofs = isize;
+ }
+found:
+ mutex_unlock(&inode->i_mutex);
+ return vfs_setpos(file, data_ofs, maxbytes);
+fail:
+ mutex_unlock(&inode->i_mutex);
+ return -ENXIO;
+}
+
+static loff_t f2fs_llseek(struct file *file, loff_t offset, int whence)
+{
+ struct inode *inode = file->f_mapping->host;
+ loff_t maxbytes = inode->i_sb->s_maxbytes;
+
+ switch (whence) {
+ case SEEK_SET:
+ case SEEK_CUR:
+ case SEEK_END:
+ return generic_file_llseek_size(file, offset, whence,
+ maxbytes, i_size_read(inode));
+ case SEEK_DATA:
+ case SEEK_HOLE:
+ return f2fs_seek_block(file, offset, whence);
+ }
+
+ return -EINVAL;
+}
+
static int f2fs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
file_accessed(file);
@@ -678,7 +772,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
#endif

const struct file_operations f2fs_file_operations = {
- .llseek = generic_file_llseek,
+ .llseek = f2fs_llseek,
.read = do_sync_read,
.write = do_sync_write,
.aio_read = generic_file_aio_read,
--
1.7.9.5