On Mon, Jul 26, 2021 at 11:46:47AM -0500, Goldwyn Rodrigues wrote: > Simplification. > > file_ra_state_init() take struct address_space *, just to use inode > pointer by dereferencing from mapping->host. > > The callers also derive mapping either by file->f_mapping, or > even file->f_mapping->host->i_mapping. > > Change file_ra_state_init() to accept struct inode * to reduce pointer > dereferencing, both in the callee and the caller. > > Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx> Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> (some adjacent comments) > diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c > index 4806295116d8..c43bf9915cda 100644 > --- a/fs/btrfs/free-space-cache.c > +++ b/fs/btrfs/free-space-cache.c > @@ -351,7 +351,7 @@ static void readahead_cache(struct inode *inode) > if (!ra) > return; > > - file_ra_state_init(ra, inode->i_mapping); > + file_ra_state_init(ra, inode); > last_index = (i_size_read(inode) - 1) >> PAGE_SHIFT; > > page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index); Why does btrfs allocate a file_ra_state using kmalloc instead of on the stack? > +++ b/include/linux/fs.h > @@ -3260,7 +3260,7 @@ extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, > > > extern void > -file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping); > +file_ra_state_init(struct file_ra_state *ra, struct inode *inode); This should move to pagemap.h (and lose the extern). I'd put it near the definition of VM_READAHEAD_PAGES. > diff --git a/mm/readahead.c b/mm/readahead.c > index d589f147f4c2..3541941df5e7 100644 > --- a/mm/readahead.c > +++ b/mm/readahead.c > @@ -31,9 +31,9 @@ > * memset *ra to zero. > */ > void > -file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping) > +file_ra_state_init(struct file_ra_state *ra, struct inode *inode) > { > - ra->ra_pages = inode_to_bdi(mapping->host)->ra_pages; > + ra->ra_pages = inode_to_bdi(inode)->ra_pages; > ra->prev_pos = -1; > } > EXPORT_SYMBOL_GPL(file_ra_state_init); I'm not entirely sure why this function is out-of-line, tbh. Would it make more sense for it to be static inline in a header?
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