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[LogFS] Split large truncated into smaller chunks

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Truncate would do an almost limitless amount of work without invoking
the garbage collector in between.  Split it up into more manageable,
though still large, chunks.

Signed-off-by: Joern Engel <joern@logfs.org>
This commit is contained in:
Joern Engel 2010-04-20 21:44:10 +02:00
parent b8639077ab
commit b6349ac89e
1 changed files with 26 additions and 8 deletions
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34
fs/logfs/readwrite.c
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@ -1837,19 +1837,37 @@ static int __logfs_truncate(struct inode *inode, u64 size)
return logfs_truncate_direct(inode, size);
}
int logfs_truncate(struct inode *inode, u64 size)
/*
* Truncate, by changing the segment file, can consume a fair amount
* of resources. So back off from time to time and do some GC.
* 8 or 2048 blocks should be well within safety limits even if
* every single block resided in a different segment.
*/
#define TRUNCATE_STEP (8 * 1024 * 1024)
int logfs_truncate(struct inode *inode, u64 target)
{
struct super_block *sb = inode->i_sb;
int err;
u64 size = i_size_read(inode);
int err = 0;
logfs_get_wblocks(sb, NULL, 1);
err = __logfs_truncate(inode, size);
if (!err)
err = __logfs_write_inode(inode, 0);
logfs_put_wblocks(sb, NULL, 1);
size = ALIGN(size, TRUNCATE_STEP);
while (size > target) {
if (size > TRUNCATE_STEP)
size -= TRUNCATE_STEP;
else
size = 0;
if (size < target)
size = target;
logfs_get_wblocks(sb, NULL, 1);
err = __logfs_truncate(inode, target);
if (!err)
err = __logfs_write_inode(inode, 0);
logfs_put_wblocks(sb, NULL, 1);
}
if (!err)
err = vmtruncate(inode, size);
err = vmtruncate(inode, target);
/* I don't trust error recovery yet. */
WARN_ON(err);