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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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2
fs/exofs/exofs.h
View file

@ -256,6 +256,8 @@ static inline int exofs_oi_read(struct exofs_i_info *oi,
}
/* inode.c */
unsigned exofs_max_io_pages(struct exofs_layout *layout,
unsigned expected_pages);
int exofs_setattr(struct dentry *, struct iattr *);
int exofs_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,

19
fs/exofs/inode.c
View file

@ -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++;

18
fs/exofs/super.c
View file

@ -390,6 +390,23 @@ static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
return 0;
}
static unsigned __ra_pages(struct exofs_layout *layout)
{
const unsigned _MIN_RA = 32; /* min 128K read-ahead */
unsigned ra_pages = layout->group_width * layout->stripe_unit /
PAGE_SIZE;
unsigned max_io_pages = exofs_max_io_pages(layout, ~0);
ra_pages *= 2; /* two stripes */
if (ra_pages < _MIN_RA)
ra_pages = roundup(_MIN_RA, ra_pages / 2);
if (ra_pages > max_io_pages)
ra_pages = max_io_pages;
return ra_pages;
}
/* @odi is valid only as long as @fscb_dev is valid */
static int exofs_devs_2_odi(struct exofs_dt_device_info *dt_dev,
struct osd_dev_info *odi)
@ -623,6 +640,7 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
}
/* set up operation vectors */
sbi->bdi.ra_pages = __ra_pages(&sbi->layout);
sb->s_bdi = &sbi->bdi;
sb->s_fs_info = sbi;
sb->s_op = &exofs_sops;