Jared Hulbert wrote:
+
+static int axfs_iget5_test(struct inode *inode, void *opaque)
+{
+ u64 *inode_number = (u64 *) opaque;
+
+ if (inode->i_sb == NULL) {
+ printk(KERN_ERR "axfs_iget5_test:"
+ " the super block is set to null\n");
+ }
+ if (inode->i_ino == *inode_number)
+ return 1; /* matches */
+ else
+ return 0; /* does not match */
+}
+
This implies inode_numbers are unique in AXFS? If so you can get rid of
the axfs_iget5_set/test logic. This is only necessary for filesystems
with non-unique inode numbers like cramfs.
+
+struct inode *axfs_create_vfs_inode(struct super_block *sb, int ino)
+{
+ struct axfs_super *sbi = AXFS_SB(sb);
+ struct inode *inode;
+ u64 size;
+
+ inode = iget5_locked(sb, ino, axfs_iget5_test, axfs_iget5_set, &ino);
If inode_numbers are unique, use iget_locked here.
+
+ if (!(inode && (inode->i_state & I_NEW)))
+ return inode;
+
+ inode->i_mode = AXFS_GET_MODE(sbi, ino);
+ inode->i_uid = AXFS_GET_UID(sbi, ino);
+ size = AXFS_GET_INODE_FILE_SIZE(sbi, ino);
+ inode->i_size = size;
What's the reason for splitting this into two lines, rather than
inode->i_size = AXFS_GET_INODE_FILE_SIZE(sbi, ino);
+ inode->i_blocks = AXFS_GET_INODE_NUM_ENTRIES(sbi, ino);
+ inode->i_blkbits = PAGE_CACHE_SIZE * 8;
+ inode->i_gid = AXFS_GET_GID(sbi, ino);
+
+ inode->i_mtime = inode->i_atime = inode->i_ctime = sbi->timestamp;
No unique per inode time? Will cause problems using AXFS for archives
etc. where preserving timestamps is important.
+ inode->i_ino = ino;
+
Unnecessary, set by iget_locked/iget_locked5
+
+static int axfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+ struct inode *inode = filp->f_dentry->d_inode;
+ struct super_block *sb = inode->i_sb;
+ struct axfs_super *sbi = AXFS_SB(sb);
+ u64 ino_number = inode->i_ino;
+ u64 entry;
+ loff_t dir_index;
+ char *name;
+ int namelen, mode;
+ int err = 0;
+
+ /* Get the current index into the directory and verify it is not beyond
+ the end of the list */
+ dir_index = filp->f_pos;
+ if (dir_index >= AXFS_GET_INODE_NUM_ENTRIES(sbi, ino_number))
+ goto out;
+
+ /* Verify the inode is for a directory */
+ if (!(S_ISDIR(inode->i_mode))) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ while (dir_index < AXFS_GET_INODE_NUM_ENTRIES(sbi, ino_number)) {
+ entry = AXFS_GET_INODE_ARRAY_INDEX(sbi, ino_number) + dir_index;
+
+ name = (char *)AXFS_GET_INODE_NAME(sbi, entry);
One to one mapping between inode number and inode name? No hard link
support...?
+ namelen = strlen(name);
+
+ mode = (int)AXFS_GET_MODE(sbi, entry);
+ err = filldir(dirent, name, namelen, dir_index, entry, mode);
+
+ if (err)
+ break;
+
+ dir_index++;
+ filp->f_pos = dir_index;
+ }
+
+out:
+ return 0;
+}
Are "." and ".." stored in the directory? If not then axfs_readdir
should fabricate them to avoid confusing applications that expect
readdir(3) to return them.
+static ssize_t axfs_file_read(struct file *filp, char __user *buf, size_t len,
+ loff_t *ppos)
+ actual_size = len > remaining ? remaining : len;
+ readlength = actual_size < PAGE_SIZE ? actual_size : PAGE_SIZE;
Use min() or min_t()
+
+static int axfs_readpage(struct file *file, struct page *page)
+{
+
+ if (node_type == Compressed) {
+ /* node is in compessed region */
+ cnode_offset = AXFS_GET_CNODE_OFFSET(sbi, node_index);
+ cnode_index = AXFS_GET_CNODE_INDEX(sbi, node_index);
+ down_write(&sbi->lock);
+ if (cnode_index != sbi->current_cnode_index) {
+ /* uncompress only necessary if different cblock */
+ ofs = AXFS_GET_CBLOCK_OFFSET(sbi, cnode_index);
+ len = AXFS_GET_CBLOCK_OFFSET(sbi, cnode_index + 1);
+ len -= ofs;
+ axfs_copy_data(sb, cblk1, &(sbi->compressed), ofs, len);
+ axfs_uncompress_block(cblk0, cblk_size, cblk1, len);
+ sbi->current_cnode_index = cnode_index;
I assume compressed blocks can be larger than PAGE_CACHE_SIZE? This
suffers from the rather obvious inefficiency that you decompress a big
block > PAGE_CACHE_SIZE, but only copy one PAGE_CACHE_SIZE page out of
it. If multiple files are being read simultaneously (a common
occurrence), then each is going to replace your one cached uncompressed
block (sbi->current_cnode_index), leading to decompressing the same
blocks over and over again on sequential file access.
readpage file A, index 1 -> decompress block X
readpage file B, index 1 -> decompress block Y (replaces X)
readpage file A, index 2 -> repeated decompress of block X (replaces Y)
readpage file B, index 2 -> repeated decompress of block Y (replaces X)
and so on.
+ }
+ downgrade_write(&sbi->lock);
+ max_len = cblk_size - cnode_offset;
+ len = max_len > PAGE_CACHE_SIZE ? PAGE_CACHE_SIZE : max_len;
Again, min() or min_t(). Lots of these.
Phillip
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