linux-ext4 - Re: Is there any reason for us to use EXT4_MAXQUOTAS_INIT

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Message-ID: <20150415232740.GB25331@thunk.org>
Date:	Wed, 15 Apr 2015 19:27:40 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Jan Kara <jack@...e.cz>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: Is there any reason for us to use EXT4_MAXQUOTAS_INIT_BLOCKS?

On Wed, Apr 15, 2015 at 10:47:54PM +0200, Jan Kara wrote:
>   Yeah, the credit estimate in ext4_symlink():
> credits = 4 + EXT4_MAXQUOTAS_INIT_BLOCKS(dir->i_sb) + EXT4_XATTR_TRANS_BLOCKS;
>   is just too pessimistic. Actually what we need for long symlinks is only
> credits for inode creation + addition to orphan list (so 4 +
> EXT4_MAXQUOTAS_TRANS_BLOCKS -- sb, gdt, bitmap, inode).

Thanks, I just wanted to check with you before I fixed this, since we
didn't have anything explicitly documenting what
EXT4_MAXQUOAS_INIT_BLOCKS did (which I'll fix as well while I'm at
it), and I didn't want to make anything assumptions that might come
back and bite us later.  Of course, the fact that ext4_symlinks was
using way more credits than ext4_mknod made it clear something was
buggy, and I couldn't imagine any circumstances why creating a long
symlink (or more correctly, only the first part of creatinga long
symlink) would require modifying 156 metadata blocks!   :-)

	       	      	       	    	       - Ted
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