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Message-ID: <2d08ef090812200743o47cd4abdwd9915653f6f4f3f7@mail.gmail.com>
Date: Sat, 20 Dec 2008 21:13:08 +0530
From: "Rohit Sharma" <imreckless@...il.com>
To: Kernelnewbies <kernelnewbies@...linux.org>,
ext4 <linux-ext4@...r.kernel.org>
Subject: ext2_block_alloc_info
A little confusion.
Just refer this structure in linux/ext2_fs_sb.h
struct ext2_block_alloc_info {
46 /* information about reservation window */
47 struct ext2_reserve_window_node rsv_window_node;
48 /*
49 * was i_next_alloc_block in ext2_inode_info
50 * is the logical (file-relative) number of the
51 * most-recently-allocated block in this file.
52 * We use this for detecting linearly ascending allocation requests.
53 */
54 __u32 last_alloc_logical_block;
55 /*
56 * Was i_next_alloc_goal in ext2_inode_info
57 * is the *physical* companion to i_next_alloc_block.
58 * it the the physical block number of the block which was
most-recentl
59 * allocated to this file. This give us the goal (target)
for the next
60 * allocation when we detect linearly ascending requests.
61 */
62 ext2_fsblk_t last_alloc_physical_block;
63};
this information is maintained by ext2 for every inode.
here last_alloc_logical_block is for every inode or its for filesystem.
I mean if we are allocating blocks for inode
it can be block no. 0 to n logically
and physically like 23 24 25 34 36 40 41 42
i mean to say
is it like
inode1 has logical blocks 1 2 3 , physical 22 23 24
inode2 has logical blocks 4 5 6 , physical 34 35 50
OR
inode1 has logical blocks 0 1 2 , physical 22 23 24
inode2 has logical blocks 0 1 2 , physical 34 35 50
??
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