Hi Vyacheslav, On Tue, 07 May 2013 16:49:37 +0400, Vyacheslav Dubeyko wrote: > Hi Ryusuke, > > On Mon, 2013-05-06 at 23:07 +0900, Ryusuke Konishi wrote: > > [snip] >> I agree to use count of descriptor blocks of ifile to >> calculate the approximate value of the total file nodes. >> >> Here are my comments on the patch: >> >> (1) Consider using nilfs_bmap_last_key() instead of repeating read >> of descriptor blocks to decide new desc_blocks count. >> The current logic may incur many device read accesses >> even if it is updated in a stepwise fashion with >> NILFS_IFILE_I(ifile)->mi.mi_desc_blocks_count. >> > > Maybe I misunderstand something but I think that nilfs_bmap_last_key() > can be less efficient solution. As I understand, descriptor block with 4 > KB in size can describe 1024 groups. Every group can describe 32768 > inodes. As a result, we can describe 32768 * 1024 = 33554432 inodes by > means of one descriptor block. So, the most frequent use-case will be > calculation with 1 descriptor block, from my point of view. Yes, I agree > that it is possible not read mi_desc_blocks_count in the beginning of > nilfs_count_free_inodes() but to use simply 1 as constant value. But, > anyway, even if we need to define a real count of descriptor blocks then > it makes only once (if we exhaust descriptor block capacity or after > mount in the case of presence of several descriptor blocks). This > counted value is saved in mi_desc_blocks_count and is used in further > calculations by means of reading mi_desc_blocks_count during exhausting > of next 33554432 inodes count. Ok, I agree that your calculation makes sense. So, repeating the read of descriptor blocks is not a problem in the real world. Please go on with the current approach. > Do you mean that nilfs_bmap_last_key() can initiate lesser read requests > as my way of using nilfs_palloc_get_desc_block() call? Yes, nilfs_bmap_last_key() does not involve read of leaf blocks of nilfs btree (i.e. data blocks including descriptor block, etc) unlike with nilfs_palloc_get_desc_block function, however it is negligible anyway as you pointed out. >> (2) Do not use __statfs_word type for local variables or arguments of >> functions. I think an integer type such as u64 should be used >> instead. >> > > Ok. I agree. > >> (3) Consider moving the main part of nilfs_count_free_inodes() >> function to alloc.c, for example, as a function like: >> >> int nilfs_palloc_count_max_entries(struct inode *inode, u64 nentries, >> u64 *nmaxentries); >> >> Then, nilfs_palloc_groups_per_desc_block() and >> nilfs_palloc_groups_count() do not need to be moved, >> and nilfs_root argument becomes eliminable from the routine >> added to ifile.c. >> > > Ok. I'll do it. > >> (4) Please consider the name convention of functions in ifile.c. >> The ifile.c includes routines related to ifile inode, >> and all its functions have the same name convention (i.e. >> nilfs_ifile_xxxx() ). >> > > Ok. I agree. > >> (5) nilfs_count_free_inodes() may return -ERANGE. >> (It's OK if inode_count is given as an argument of the function.) >> But, nilfs_statfs() should not return -ERANGE as-is. >> >> In that case, I think nilfs_statfs() should output a warning >> message and ignore the error code. >> > > Currently, it is processed returned error of nilfs_count_free_blocks() > in nilfs_statfs(). Yes, nilfs_count_free_blocks() doesn't return any > error really. But, potentially, nilfs_statfs() can return error from > this method. So, as I understand, you suggest simply to warn in > nilfs_statfs() about errors in called methods and doesn't return these > errors from it. Am I correct? I mean that only -ERANGE should not be returned to user space as-is because it looks an internal error code indicating that there is an inconsistency in the file system metadata. Other errors like -EIO or -ENOMEM can be returned to user space. These error codes are actually specified in the man page of statfs. With regards, Ryusuke Konishi > With the best regards, > Vyacheslav Dubeyko. > >> Regards, >> Ryusuke Konishi >> > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
