On 02/03/2011 01:22 PM, Boaz Harrosh wrote: > > commit: [115e19c] exofs: Set i_mapping->backing_dev_info anyway > > Has caused a regression in read-ahead because bdi_init() does > not set bdi->ra_pages to anything and it was left as zero. > So when moving all inodes to point to the super-block's > bdi, they all had ra_pages disabled. > > Should bdi_init() be patched to some sane default value? > > I fix that by calculating a read_ahead that is: > - preferable 2 stripes long (I'll add a mount option to next Kernel) > - 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 a page times > # of devices) > > This is a regression since the 2.6.37 Kernel. > 2.6.36 was fine >
Dear Greg, Stable Tree. I see that Linus has already merged the revert of the offending patch, as a BUG fix for above. That's fine. PLEASE forget about this patch. (Sorry for the noise) I will submit this patch as a regular enhancement for the next merge window. Thanks Boaz > CC: Stable Tree <[email protected]> > Signed-off-by: Boaz Harrosh <[email protected]> > --- > fs/exofs/exofs.h | 2 ++ > fs/exofs/inode.c | 17 +++++++++++++---- > fs/exofs/super.c | 18 ++++++++++++++++++ > 3 files changed, 33 insertions(+), 4 deletions(-) > > diff --git a/fs/exofs/exofs.h b/fs/exofs/exofs.h > index 2dc925f..99fcb91 100644 > --- a/fs/exofs/exofs.h > +++ b/fs/exofs/exofs.h > @@ -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, > diff --git a/fs/exofs/inode.c b/fs/exofs/inode.c > index 4268542..deede10 100644 > --- a/fs/exofs/inode.c > +++ b/fs/exofs/inode.c > @@ -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 *), > diff --git a/fs/exofs/super.c b/fs/exofs/super.c > index 79c3ae6..75d42ac 100644 > --- a/fs/exofs/super.c > +++ b/fs/exofs/super.c > @@ -383,6 +383,23 @@ 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) > @@ -616,6 +633,7 @@ 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; _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
