Jared Hulbert wrote:
+/***************** functions in other axfs files ******************************/
+int axfs_get_sb(struct file_system_type *, int, const char *, void *,
+ struct vfsmount *);
This is neither implemented nor used in axfs_inode.c - why define it here?
+void axfs_kill_super(struct super_block *);
Same for this one.
+void axfs_profiling_add(struct axfs_super *, unsigned long, unsigned int);
+int axfs_copy_mtd(struct super_block *, void *, u64, u64);
+int axfs_copy_block(struct super_block *, void *, u64, u64);
These are used, but not implemented here. Please consider putting them
in a header file
+static int axfs_copy_data(struct super_block *sb, void *dst,
+ struct axfs_region_desc *region, u64 offset, u64 len)
+{
+ u64 mmapped = 0;
+ u64 end = region->fsoffset + offset + len;
+ u64 begin = region->fsoffset + offset;
+ u64 left;
+ void *addr;
+ void *newdst;
+ struct axfs_super *sbi = AXFS_SB(sb);
+
+ if (len == 0)
+ return 0;
+
+ if (region->virt_addr) {
+ if (sbi->mmap_size >= end) {
+ mmapped = len;
+ } else if (sbi->mmap_size > begin) {
+ mmapped = sbi->mmap_size - begin;
+ }
+ }
You can save braces and make the code more readable here:
=> if (sbi->mmap_size >= end)
mmapped = len;
else if (sbi->mmap_size > begin)
mmapped = si->mmap_size - begin;
+struct inode *axfs_create_vfs_inode(struct super_block *sb, int ino)
+{
+ struct axfs_super *sbi = AXFS_SB(sb);
+ struct inode *inode;
+ u64 size;
[SNIP]
+ size = AXFS_GET_INODE_FILE_SIZE(sbi, ino);
+ inode->i_size = size;
The variable size is not needed. Do
inode->i_size = AXFS_GET_INODE_FILE_SIZE(sbi, ino);
+static struct dentry *axfs_lookup(struct inode *dir, struct dentry *dentry,
+ struct nameidata *nd)
+{
+ struct super_block *sb = dir->i_sb;
+ struct axfs_super *sbi = AXFS_SB(sb);
+ u64 ino_number = dir->i_ino;
+ u64 dir_index = 0;
+ u64 entry;
+ char *name;
+ int namelen, err;
+
+ while (dir_index < AXFS_GET_INODE_NUM_ENTRIES(sbi, ino_number)) {
+ entry = AXFS_GET_INODE_ARRAY_INDEX(sbi, ino_number);
+ entry += dir_index;
+
+ name = AXFS_GET_INODE_NAME(sbi, entry);
+ namelen = strlen(name);
+
+ /* fast test, the entries are sorted alphabetically and the
+ * first letter is smaller than the first letter in the search
+ * name then it isn't in this directory. Keeps this loop from
+ * needing to scan through always.
+ */
+ if (dentry->d_name.name[0] < name[0])
+ break;
+
+ dir_index++;
+
+ /* Quick check that the name is roughly the right length */
+ if (dentry->d_name.len != namelen)
+ continue;
+
+ err = memcmp(dentry->d_name.name, name, namelen);
+ if (err > 0)
+ continue;
+
+ /* The file name isn't present in the directory. */
+ if (err < 0)
+ break;
Very ingenious way to compare strings. strncmp also stops after the
first character if it does'nt fit. I doubt this has a measurable
performance advantage over using strncmp, please consider to replace
this logic to make the code smaller and more readable. See lib/string.c.
+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;
+ }
Well, -ENOTDIR would be the correct return code. You can remove that
sanity check alltogether, vfs_readdir makes sure this is the right
file type. If you really want to check, make it
BUG_ON(!S_ISDIR(inode->i_mode));
+static int axfs_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ struct file *file = vma->vm_file;
+ struct inode *inode = file->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 array_index;
+
+ array_index = AXFS_GET_INODE_ARRAY_INDEX(sbi, ino_number) + vmf->pgoff;
+
+ /* if that pages are marked for write they will probably end up in RAM
+ therefore we don't want their counts for being XIP'd */
+ if (!(vma->vm_flags & VM_WRITE))
+ axfs_profiling_add(sbi, array_index, ino_number);
Thats very inacurate profiling, it does never count MAP_PRIVATE
mappings which is the regular case for executables and libraries. When
booting an enterprise distro, my sniff test shows that only about 5%
of the MAP_PRIVATE mappings get COW'ed. To get correct statistics, it
might be a good idea to find a way to add here and substract during
cow. Or to scan these mappings when the profiling information is being
retrieved - the readonly bit in the pte gives the right indication for
MIXEDMAP mappings.
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