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exofs: Override read-ahead to align on stripe_size

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* Set all inode->i_mapping->backing_dev_info to point to
  the per super-block sb->s_bdi.

* Calculating a read_ahead that is:
  - preferable 2 stripes long
    (Future patch will add a mount option to override this)
  - Minimum 128K aligned up to stripe-size
  - Caped to maximum-IO-sizes round down to stripe_size.
    (Max sizes are governed by max bio-size that fits in a page
     times number-of-devices)

CC: Marc Dionne <marc.c.dionne@gmail.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
This commit is contained in:
bharrosh@panasas.com
2010-10-07 14:28:18 -04:00
committed by Boaz Harrosh
parent 97178b7b6c
commit 66cd6cad49
3 changed files with 35 additions and 4 deletions
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19
fs/exofs/inode.c
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@ -43,6 +43,17 @@ enum { BIO_MAX_PAGES_KMALLOC =
PAGE_SIZE / sizeof(struct page *),
};
unsigned exofs_max_io_pages(struct exofs_layout *layout,
unsigned expected_pages)
{
unsigned pages = min_t(unsigned, expected_pages, MAX_PAGES_KMALLOC);
/* TODO: easily support bio chaining */
pages = min_t(unsigned, pages,
layout->group_width * BIO_MAX_PAGES_KMALLOC);
return pages;
}
struct page_collect {
struct exofs_sb_info *sbi;
struct inode *inode;
@ -97,8 +108,7 @@ static void _pcol_reset(struct page_collect *pcol)
static int pcol_try_alloc(struct page_collect *pcol)
{
unsigned pages = min_t(unsigned, pcol->expected_pages,
MAX_PAGES_KMALLOC);
unsigned pages;
if (!pcol->ios) { /* First time allocate io_state */
int ret = exofs_get_io_state(&pcol->sbi->layout, &pcol->ios);
@ -108,8 +118,7 @@ static int pcol_try_alloc(struct page_collect *pcol)
}
/* TODO: easily support bio chaining */
pages = min_t(unsigned, pages,
pcol->sbi->layout.group_width * BIO_MAX_PAGES_KMALLOC);
pages = exofs_max_io_pages(&pcol->sbi->layout, pcol->expected_pages);
for (; pages; pages >>= 1) {
pcol->pages = kmalloc(pages * sizeof(struct page *),
@ -1049,6 +1058,7 @@ struct inode *exofs_iget(struct super_block *sb, unsigned long ino)
memcpy(oi->i_data, fcb.i_data, sizeof(fcb.i_data));
}
inode->i_mapping->backing_dev_info = sb->s_bdi;
if (S_ISREG(inode->i_mode)) {
inode->i_op = &exofs_file_inode_operations;
inode->i_fop = &exofs_file_operations;
@ -1149,6 +1159,7 @@ struct inode *exofs_new_inode(struct inode *dir, int mode)
sbi = sb->s_fs_info;
inode->i_mapping->backing_dev_info = sb->s_bdi;
sb->s_dirt = 1;
inode_init_owner(inode, dir, mode);
inode->i_ino = sbi->s_nextid++;