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Message-Id: <1170836750.4355.36.camel@localhost.localdomain>
Date: Wed, 07 Feb 2007 00:25:50 -0800
From: Mingming Cao <cmm@...ibm.com>
To: "Amit K. Arora" <aarora@...ux.vnet.ibm.com>
Cc: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
suparna@...ibm.com, alex@...sterfs.com, suzuki@...ibm.com
Subject: Re: Testing ext4 persistent preallocation patches for 64 bit
features
On Wed, 2007-02-07 at 13:18 +0530, Amit K. Arora wrote:
> I plan to test the persistent preallocation patches on a huge sparse
> device, to know if >32 bit physical block numbers (upto 48bit) behave as
> expected.
Thanks!
> I have following questions for this and will appreciate
> suggestions here:
> c) Do I need to put some hack in the filesystem code for above (to
> allocate >32 bit physical block numbers) ?
>
I had a ext3 hack patch before to allow application specify which block
group is the targeted block allocation group,using ioctl command, so to
allocate >32 bit physical block numbers it just set the target block
group beyond 2**(32-15) = 2**17. patch is below..
BTW, have you considered
- move the preallocation code in ioctl to a seperate function, and call
that function from ioctl? That way we could easily switch to
posix_falloc later.
- Test preallocation with mapped IO?
- disable preallocation if the filesystem free blocks is under some low
watermarks, to save space for near future real block allocation?
- is de-preallocation something worth doing?
Mingming
---
linux-2.6.16-ming/fs/ext3/balloc.c | 24 ++++++++++++++---------
linux-2.6.16-ming/fs/ext3/ioctl.c | 29 ++++++++++++++++++++++++++++
linux-2.6.16-ming/include/linux/ext3_fs.h | 1
linux-2.6.16-ming/include/linux/ext3_fs_i.h | 1
4 files changed, 46 insertions(+), 9 deletions(-)
diff -puN fs/ext3/ioctl.c~ext3_set_alloc_blk_group_hack fs/ext3/ioctl.c
--- linux-2.6.16/fs/ext3/ioctl.c~ext3_set_alloc_blk_group_hack 2006-03-28 15:19:58.000000000 -0800
+++ linux-2.6.16-ming/fs/ext3/ioctl.c 2006-03-28 15:54:14.507288400 -0800
@@ -22,6 +22,7 @@ int ext3_ioctl (struct inode * inode, st
struct ext3_inode_info *ei = EXT3_I(inode);
unsigned int flags;
unsigned short rsv_window_size;
+ unsigned int blk_group;
ext3_debug ("cmd = %u, arg = %lu\n", cmd, arg);
@@ -193,6 +194,34 @@ flags_err:
mutex_unlock(&ei->truncate_mutex);
return 0;
}
+ case EXT3_IOC_SETALLOCBLKGRP: {
+
+ if (!test_opt(inode->i_sb, RESERVATION) ||!S_ISREG(inode->i_mode))
+ return -ENOTTY;
+
+ if (IS_RDONLY(inode))
+ return -EROFS;
+
+ if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
+ return -EACCES;
+
+ if (get_user(blk_group, (int __user *)arg))
+ return -EFAULT;
+
+ /*
+ * need to allocate reservation structure for this inode
+ * before set the window size
+ */
+ mutex_lock(&ei->truncate_mutex);
+ if (!ei->i_block_alloc_info)
+ ext3_init_block_alloc_info(inode);
+
+ if (ei->i_block_alloc_info){
+ ei->i_block_alloc_info->goal_block_group = blk_group;
+ }
+ mutex_unlock(&ei->truncate_mutex);
+ return 0;
+ }
case EXT3_IOC_GROUP_EXTEND: {
unsigned long n_blocks_count;
struct super_block *sb = inode->i_sb;
diff -puN include/linux/ext3_fs.h~ext3_set_alloc_blk_group_hack include/linux/ext3_fs.h
--- linux-2.6.16/include/linux/ext3_fs.h~ext3_set_alloc_blk_group_hack 2006-03-28 15:42:51.000000000 -0800
+++ linux-2.6.16-ming/include/linux/ext3_fs.h 2006-03-28 15:51:48.321237417 -0800
@@ -238,6 +238,7 @@ struct ext3_new_group_data {
#endif
#define EXT3_IOC_GETRSVSZ _IOR('f', 5, long)
#define EXT3_IOC_SETRSVSZ _IOW('f', 6, long)
+#define EXT3_IOC_SETALLOCBLKGRP _IOW('f', 9, long)
/*
* Mount options
diff -puN include/linux/ext3_fs_i.h~ext3_set_alloc_blk_group_hack include/linux/ext3_fs_i.h
--- linux-2.6.16/include/linux/ext3_fs_i.h~ext3_set_alloc_blk_group_hack 2006-03-28 15:43:59.000000000 -0800
+++ linux-2.6.16-ming/include/linux/ext3_fs_i.h 2006-03-28 15:47:54.274367219 -0800
@@ -51,6 +51,7 @@ struct ext3_block_alloc_info {
* allocation when we detect linearly ascending requests.
*/
__u32 last_alloc_physical_block;
+ __u32 goal_block_group;
};
#define rsv_start rsv_window._rsv_start
diff -puN fs/ext3/balloc.c~ext3_set_alloc_blk_group_hack fs/ext3/balloc.c
--- linux-2.6.16/fs/ext3/balloc.c~ext3_set_alloc_blk_group_hack 2006-03-28 15:45:30.000000000 -0800
+++ linux-2.6.16-ming/fs/ext3/balloc.c 2006-03-28 16:03:55.770850040 -0800
@@ -285,6 +285,7 @@ void ext3_init_block_alloc_info(struct i
rsv->rsv_alloc_hit = 0;
block_i->last_alloc_logical_block = 0;
block_i->last_alloc_physical_block = 0;
+ block_i->goal_block_group = 0;
}
ei->i_block_alloc_info = block_i;
}
@@ -1263,15 +1264,20 @@ unsigned long ext3_new_blocks(handle_t *
*errp = -ENOSPC;
goto out;
}
-
- /*
- * First, test whether the goal block is free.
- */
- if (goal < le32_to_cpu(es->s_first_data_block) ||
- goal >= le32_to_cpu(es->s_blocks_count))
- goal = le32_to_cpu(es->s_first_data_block);
- group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
- EXT3_BLOCKS_PER_GROUP(sb);
+ if (block_i->goal_block_group) {
+ group_no = block_i->goal_block_group;
+ goal = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) + group_no * EXT3_BLOCKS_PER_GROUP(sb);
+ block_i->goal_block_group = 0;
+ } else {
+ /*
+ * First, test whether the goal block is free.
+ */
+ if (goal < le32_to_cpu(es->s_first_data_block) ||
+ goal >= le32_to_cpu(es->s_blocks_count))
+ goal = le32_to_cpu(es->s_first_data_block);
+ group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
+ EXT3_BLOCKS_PER_GROUP(sb);
+ }
gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
if (!gdp)
goto io_error;
_
-
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