| Message ID | 20231016201114.1928083-2-willy@infradead.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Finish the create_empty_buffers() transition | expand |
On Tue, Oct 17, 2023 at 5:11 AM Matthew Wilcox (Oracle) wrote: > > Rename grow_dev_page() to grow_dev_folio() and make it return a bool. > Document what that bool means; it's more subtle than it first appears. > Also rename the 'failed' label to 'unlock' beacuse it's not exactly > 'failed'. It just hasn't succeeded. > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > --- > fs/buffer.c | 39 ++++++++++++++++++++++----------------- > 1 file changed, 22 insertions(+), 17 deletions(-) > > diff --git a/fs/buffer.c b/fs/buffer.c > index b33cc74e9649..dec41d84044b 100644 > --- a/fs/buffer.c > +++ b/fs/buffer.c > @@ -1024,24 +1024,26 @@ static sector_t folio_init_buffers(struct folio *folio, > } > > /* > - * Create the page-cache page that contains the requested block. > + * Create the page-cache folio that contains the requested block. > * > * This is used purely for blockdev mappings. > + * > + * Returns false if we have a 'permanent' failure. Returns true if > + * we succeeded, or the caller should retry. > */ > -static int > -grow_dev_page(struct block_device *bdev, sector_t block, > +static bool grow_dev_folio(struct block_device *bdev, sector_t block, > pgoff_t index, int size, int sizebits, gfp_t gfp) > { > struct inode *inode = bdev->bd_inode; > struct folio *folio; > struct buffer_head *bh; > sector_t end_block; > - int ret = 0; > + bool ret; > > folio = __filemap_get_folio(inode->i_mapping, index, > FGP_LOCK | FGP_ACCESSED | FGP_CREAT, gfp); > if (IS_ERR(folio)) > - return PTR_ERR(folio); > + return false; > > bh = folio_buffers(folio); > if (bh) { > @@ -1050,14 +1052,17 @@ grow_dev_page(struct block_device *bdev, sector_t block, > (sector_t)index << sizebits, size); > goto done; > } > + > + /* Caller should retry if this call fails */ > + ret = true; > if (!try_to_free_buffers(folio)) > - goto failed; > + goto unlock; > } > > - ret = -ENOMEM; > + ret = false; > bh = folio_alloc_buffers(folio, size, gfp | __GFP_ACCOUNT); > if (!bh) > - goto failed; > + goto unlock; > > /* > * Link the folio to the buffers and initialise them. Take the > @@ -1070,19 +1075,19 @@ grow_dev_page(struct block_device *bdev, sector_t block, > (sector_t)index << sizebits, size); > spin_unlock(&inode->i_mapping->private_lock); > done: > - ret = (block < end_block) ? 1 : -ENXIO; > -failed: > + ret = block < end_block; > +unlock: > folio_unlock(folio); > folio_put(folio); > return ret; > } > > /* > - * Create buffers for the specified block device block's page. If > - * that page was dirty, the buffers are set dirty also. > + * Create buffers for the specified block device block's folio. If > + * that folio was dirty, the buffers are set dirty also. > */ > -static int > -grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) > +static bool grow_buffers(struct block_device *bdev, sector_t block, > + int size, gfp_t gfp) > { > pgoff_t index; > int sizebits; > @@ -1099,11 +1104,11 @@ grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) > "device %pg\n", > __func__, (unsigned long long)block, > bdev); > - return -EIO; > + return false; > } > > - /* Create a page with the proper size buffers.. */ > - return grow_dev_page(bdev, block, index, size, sizebits, gfp); > + /* Create a folio with the proper size buffers.. */ > + return grow_dev_folio(bdev, block, index, size, sizebits, gfp); > } > > static struct buffer_head * > -- > 2.40.1 This changes the return type of grow_buffers() from "int" to "bool". But, it seems that the caller, __getblk_slow(), has not changed the type of the variable "ret" that receives its return value: for (;;) { struct buffer_head *bh; int ret; bh = __find_get_block(bdev, block, size); if (bh) return bh; ret = grow_buffers(bdev, block, size, gfp); if (ret < 0) return NULL; } So, it looks like the error check immediately after calling grow_buffers() will not branch like before. Is this okay ? Or, am I missing some other changes? Also, there is a typo in the changelog: "beacuse" -> "because". Regards, Ryusuke Konishi
On Wed, Oct 18, 2023 at 04:41:44AM +0900, Ryusuke Konishi wrote: > On Tue, Oct 17, 2023 at 5:11 AM Matthew Wilcox (Oracle) wrote: > > > > Rename grow_dev_page() to grow_dev_folio() and make it return a bool. > > Document what that bool means; it's more subtle than it first appears. > > Also rename the 'failed' label to 'unlock' beacuse it's not exactly > > 'failed'. It just hasn't succeeded. > > This changes the return type of grow_buffers() from "int" to "bool". > But, it seems that the caller, __getblk_slow(), has not changed the > type of the variable "ret" that receives its return value: [...] > > So, it looks like the error check immediately after calling > grow_buffers() will not branch like before. > Is this okay ? Or, am I missing some other changes? > > Also, there is a typo in the changelog: "beacuse" -> "because". Argh, yes. Andrew, please drop this patch for now. I'll submit something better next cycle.
diff --git a/fs/buffer.c b/fs/buffer.c index b33cc74e9649..dec41d84044b 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1024,24 +1024,26 @@ static sector_t folio_init_buffers(struct folio *folio, } /* - * Create the page-cache page that contains the requested block. + * Create the page-cache folio that contains the requested block. * * This is used purely for blockdev mappings. + * + * Returns false if we have a 'permanent' failure. Returns true if + * we succeeded, or the caller should retry. */ -static int -grow_dev_page(struct block_device *bdev, sector_t block, +static bool grow_dev_folio(struct block_device *bdev, sector_t block, pgoff_t index, int size, int sizebits, gfp_t gfp) { struct inode *inode = bdev->bd_inode; struct folio *folio; struct buffer_head *bh; sector_t end_block; - int ret = 0; + bool ret; folio = __filemap_get_folio(inode->i_mapping, index, FGP_LOCK | FGP_ACCESSED | FGP_CREAT, gfp); if (IS_ERR(folio)) - return PTR_ERR(folio); + return false; bh = folio_buffers(folio); if (bh) { @@ -1050,14 +1052,17 @@ grow_dev_page(struct block_device *bdev, sector_t block, (sector_t)index << sizebits, size); goto done; } + + /* Caller should retry if this call fails */ + ret = true; if (!try_to_free_buffers(folio)) - goto failed; + goto unlock; } - ret = -ENOMEM; + ret = false; bh = folio_alloc_buffers(folio, size, gfp | __GFP_ACCOUNT); if (!bh) - goto failed; + goto unlock; /* * Link the folio to the buffers and initialise them. Take the @@ -1070,19 +1075,19 @@ grow_dev_page(struct block_device *bdev, sector_t block, (sector_t)index << sizebits, size); spin_unlock(&inode->i_mapping->private_lock); done: - ret = (block < end_block) ? 1 : -ENXIO; -failed: + ret = block < end_block; +unlock: folio_unlock(folio); folio_put(folio); return ret; } /* - * Create buffers for the specified block device block's page. If - * that page was dirty, the buffers are set dirty also. + * Create buffers for the specified block device block's folio. If + * that folio was dirty, the buffers are set dirty also. */ -static int -grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) +static bool grow_buffers(struct block_device *bdev, sector_t block, + int size, gfp_t gfp) { pgoff_t index; int sizebits; @@ -1099,11 +1104,11 @@ grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) "device %pg\n", __func__, (unsigned long long)block, bdev); - return -EIO; + return false; } - /* Create a page with the proper size buffers.. */ - return grow_dev_page(bdev, block, index, size, sizebits, gfp); + /* Create a folio with the proper size buffers.. */ + return grow_dev_folio(bdev, block, index, size, sizebits, gfp); } static struct buffer_head *
Rename grow_dev_page() to grow_dev_folio() and make it return a bool. Document what that bool means; it's more subtle than it first appears. Also rename the 'failed' label to 'unlock' beacuse it's not exactly 'failed'. It just hasn't succeeded. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> --- fs/buffer.c | 39 ++++++++++++++++++++++----------------- 1 file changed, 22 insertions(+), 17 deletions(-)