2024-05-15 06:00:30

by Daniel Gomez

Subject: [PATCH 11/12] shmem: add file length arg in shmem_get_folio() path

In preparation for large folio in the write and fallocate paths, add
file length argument in shmem_get_folio() path to be able to calculate
the folio order based on the file size. Use of order-0 (PAGE_SIZE) for
read, page cache read, and vm fault.

This enables high order folios in the write and fallocate path once the
folio order is calculated based on the length.

Signed-off-by: Daniel Gomez <[email protected]>
---
fs/xfs/scrub/xfile.c | 6 +++---
fs/xfs/xfs_buf_mem.c | 3 ++-
include/linux/shmem_fs.h | 2 +-
mm/khugepaged.c | 3 ++-
mm/shmem.c | 35 ++++++++++++++++++++---------------
mm/userfaultfd.c | 2 +-
6 files changed, 29 insertions(+), 22 deletions(-)

diff --git a/fs/xfs/scrub/xfile.c b/fs/xfs/scrub/xfile.c
index 8cdd863db585..4905f5e4cb5d 100644
--- a/fs/xfs/scrub/xfile.c
+++ b/fs/xfs/scrub/xfile.c
@@ -127,7 +127,7 @@ xfile_load(
unsigned int offset;

if (shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
- SGP_READ) < 0)
+ SGP_READ, PAGE_SIZE) < 0)
break;
if (!folio) {
/*
@@ -197,7 +197,7 @@ xfile_store(
unsigned int offset;

if (shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
- SGP_CACHE) < 0)
+ SGP_CACHE, PAGE_SIZE) < 0)
break;
if (filemap_check_wb_err(inode->i_mapping, 0)) {
folio_unlock(folio);
@@ -268,7 +268,7 @@ xfile_get_folio(

pflags = memalloc_nofs_save();
error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
- (flags & XFILE_ALLOC) ? SGP_CACHE : SGP_READ);
+ (flags & XFILE_ALLOC) ? SGP_CACHE : SGP_READ, PAGE_SIZE);
memalloc_nofs_restore(pflags);
if (error)
return ERR_PTR(error);
diff --git a/fs/xfs/xfs_buf_mem.c b/fs/xfs/xfs_buf_mem.c
index 9bb2d24de709..784c81d35a1f 100644
--- a/fs/xfs/xfs_buf_mem.c
+++ b/fs/xfs/xfs_buf_mem.c
@@ -149,7 +149,8 @@ xmbuf_map_page(
return -ENOMEM;
}

- error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio, SGP_CACHE);
+ error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio, SGP_CACHE,
+ PAGE_SIZE);
if (error)
return error;

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index 3fb18f7eb73e..bc59b4a00228 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -142,7 +142,7 @@ enum sgp_type {
};

int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
- enum sgp_type sgp);
+ enum sgp_type sgp, size_t len);
struct folio *shmem_read_folio_gfp(struct address_space *mapping,
pgoff_t index, gfp_t gfp);

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 38830174608f..947770ded68c 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1863,7 +1863,8 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
xas_unlock_irq(&xas);
/* swap in or instantiate fallocated page */
if (shmem_get_folio(mapping->host, index,
- &folio, SGP_NOALLOC)) {
+ &folio, SGP_NOALLOC,
+ PAGE_SIZE)) {
result = SCAN_FAIL;
goto xa_unlocked;
}
diff --git a/mm/shmem.c b/mm/shmem.c
index d531018ffece..fcd2c9befe19 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1134,7 +1134,7 @@ static struct folio *shmem_get_partial_folio(struct inode *inode, pgoff_t index)
* (although in some cases this is just a waste of time).
*/
folio = NULL;
- shmem_get_folio(inode, index, &folio, SGP_READ);
+ shmem_get_folio(inode, index, &folio, SGP_READ, PAGE_SIZE);
return folio;
}

@@ -1844,7 +1844,7 @@ static struct folio *shmem_alloc_folio(gfp_t gfp, struct shmem_inode_info *info,

static struct folio *shmem_alloc_and_add_folio(gfp_t gfp,
struct inode *inode, pgoff_t index,
- struct mm_struct *fault_mm, bool huge)
+ struct mm_struct *fault_mm, bool huge, size_t len)
{
struct address_space *mapping = inode->i_mapping;
struct shmem_inode_info *info = SHMEM_I(inode);
@@ -2173,7 +2173,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
*/
static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
struct folio **foliop, enum sgp_type sgp, gfp_t gfp,
- struct vm_fault *vmf, vm_fault_t *fault_type)
+ struct vm_fault *vmf, vm_fault_t *fault_type, size_t len)
{
struct vm_area_struct *vma = vmf ? vmf->vma : NULL;
struct mm_struct *fault_mm;
@@ -2258,7 +2258,7 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
huge_gfp = vma_thp_gfp_mask(vma);
huge_gfp = limit_gfp_mask(huge_gfp, gfp);
folio = shmem_alloc_and_add_folio(huge_gfp,
- inode, index, fault_mm, true);
+ inode, index, fault_mm, true, len);
if (!IS_ERR(folio)) {
count_vm_event(THP_FILE_ALLOC);
goto alloced;
@@ -2267,7 +2267,8 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
goto repeat;
}

- folio = shmem_alloc_and_add_folio(gfp, inode, index, fault_mm, false);
+ folio = shmem_alloc_and_add_folio(gfp, inode, index, fault_mm, false,
+ len);
if (IS_ERR(folio)) {
error = PTR_ERR(folio);
if (error == -EEXIST)
@@ -2377,10 +2378,10 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
* Return: 0 if successful, else a negative error code.
*/
int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
- enum sgp_type sgp)
+ enum sgp_type sgp, size_t len)
{
return shmem_get_folio_gfp(inode, index, foliop, sgp,
- mapping_gfp_mask(inode->i_mapping), NULL, NULL);
+ mapping_gfp_mask(inode->i_mapping), NULL, NULL, len);
}
EXPORT_SYMBOL_GPL(shmem_get_folio);

@@ -2475,7 +2476,7 @@ static vm_fault_t shmem_fault(struct vm_fault *vmf)

WARN_ON_ONCE(vmf->page != NULL);
err = shmem_get_folio_gfp(inode, vmf->pgoff, &folio, SGP_CACHE,
- gfp, vmf, &ret);
+ gfp, vmf, &ret, PAGE_SIZE);
if (err)
return vmf_error(err);
if (folio) {
@@ -2954,6 +2955,9 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
struct folio *folio;
int ret = 0;

+ if (!mapping_large_folio_support(mapping))
+ len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));
+
/* i_rwsem is held by caller */
if (unlikely(info->seals & (F_SEAL_GROW |
F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
@@ -2963,7 +2967,7 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
return -EPERM;
}

- ret = shmem_get_folio(inode, index, &folio, SGP_WRITE);
+ ret = shmem_get_folio(inode, index, &folio, SGP_WRITE, len);
if (ret)
return ret;

@@ -3083,7 +3087,7 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
break;
}

- error = shmem_get_folio(inode, index, &folio, SGP_READ);
+ error = shmem_get_folio(inode, index, &folio, SGP_READ, PAGE_SIZE);
if (error) {
if (error == -EINVAL)
error = 0;
@@ -3260,7 +3264,7 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
break;

error = shmem_get_folio(inode, *ppos / PAGE_SIZE, &folio,
- SGP_READ);
+ SGP_READ, PAGE_SIZE);
if (error) {
if (error == -EINVAL)
error = 0;
@@ -3469,7 +3473,8 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
error = -ENOMEM;
else
error = shmem_get_folio(inode, index, &folio,
- SGP_FALLOC);
+ SGP_FALLOC,
+ (end - index) << PAGE_SHIFT);
if (error) {
info->fallocend = undo_fallocend;
/* Remove the !uptodate folios we added */
@@ -3822,7 +3827,7 @@ static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir,
} else {
inode_nohighmem(inode);
inode->i_mapping->a_ops = &shmem_aops;
- error = shmem_get_folio(inode, 0, &folio, SGP_WRITE);
+ error = shmem_get_folio(inode, 0, &folio, SGP_WRITE, PAGE_SIZE);
if (error)
goto out_remove_offset;
inode->i_op = &shmem_symlink_inode_operations;
@@ -3868,7 +3873,7 @@ static const char *shmem_get_link(struct dentry *dentry, struct inode *inode,
return ERR_PTR(-ECHILD);
}
} else {
- error = shmem_get_folio(inode, 0, &folio, SGP_READ);
+ error = shmem_get_folio(inode, 0, &folio, SGP_READ, PAGE_SIZE);
if (error)
return ERR_PTR(error);
if (!folio)
@@ -5255,7 +5260,7 @@ struct folio *shmem_read_folio_gfp(struct address_space *mapping,
int error;

error = shmem_get_folio_gfp(inode, index, &folio, SGP_CACHE,
- gfp, NULL, NULL);
+ gfp, NULL, NULL, PAGE_SIZE);
if (error)
return ERR_PTR(error);

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 3c3539c573e7..540a0c2d4325 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -359,7 +359,7 @@ static int mfill_atomic_pte_continue(pmd_t *dst_pmd,
struct page *page;
int ret;

- ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC);
+ ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC, PAGE_SIZE);
/* Our caller expects us to return -EFAULT if we failed to find folio */
if (ret == -ENOENT)
ret = -EFAULT;
--
2.43.0

2024-05-15 17:53:17

by kernel test robot

Subject: Re: [PATCH 11/12] shmem: add file length arg in shmem_get_folio() path

Hi Daniel,

kernel test robot noticed the following build warnings:

[auto build test WARNING on akpm-mm/mm-everything]
[also build test WARNING on xfs-linux/for-next brauner-vfs/vfs.all linus/master v6.9 next-20240515]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Daniel-Gomez/splice-don-t-check-for-uptodate-if-partially-uptodate-is-impl/20240515-135925
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20240515055719.32577-12-da.gomez%40samsung.com
patch subject: [PATCH 11/12] shmem: add file length arg in shmem_get_folio() path
config: openrisc-defconfig (https://download.01.org/0day-ci/archive/20240516/[email protected]/config)
compiler: or1k-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240516/[email protected]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All warnings (new ones prefixed by >>):

>> mm/shmem.c:2382: warning: Function parameter or struct member 'len' not described in 'shmem_get_folio'


vim +2382 mm/shmem.c

^1da177e4c3f41 Linus Torvalds 2005-04-16 2356
d7468609ee0f90 Christoph Hellwig 2024-02-19 2357 /**
d7468609ee0f90 Christoph Hellwig 2024-02-19 2358 * shmem_get_folio - find, and lock a shmem folio.
d7468609ee0f90 Christoph Hellwig 2024-02-19 2359 * @inode: inode to search
d7468609ee0f90 Christoph Hellwig 2024-02-19 2360 * @index: the page index.
d7468609ee0f90 Christoph Hellwig 2024-02-19 2361 * @foliop: pointer to the folio if found
d7468609ee0f90 Christoph Hellwig 2024-02-19 2362 * @sgp: SGP_* flags to control behavior
d7468609ee0f90 Christoph Hellwig 2024-02-19 2363 *
d7468609ee0f90 Christoph Hellwig 2024-02-19 2364 * Looks up the page cache entry at @inode & @index. If a folio is
d7468609ee0f90 Christoph Hellwig 2024-02-19 2365 * present, it is returned locked with an increased refcount.
d7468609ee0f90 Christoph Hellwig 2024-02-19 2366 *
9d8b36744935f8 Christoph Hellwig 2024-02-19 2367 * If the caller modifies data in the folio, it must call folio_mark_dirty()
9d8b36744935f8 Christoph Hellwig 2024-02-19 2368 * before unlocking the folio to ensure that the folio is not reclaimed.
9d8b36744935f8 Christoph Hellwig 2024-02-19 2369 * There is no need to reserve space before calling folio_mark_dirty().
9d8b36744935f8 Christoph Hellwig 2024-02-19 2370 *
d7468609ee0f90 Christoph Hellwig 2024-02-19 2371 * When no folio is found, the behavior depends on @sgp:
8d4dd9d741c330 Akira Yokosawa 2024-02-27 2372 * - for SGP_READ, *@foliop is %NULL and 0 is returned
8d4dd9d741c330 Akira Yokosawa 2024-02-27 2373 * - for SGP_NOALLOC, *@foliop is %NULL and -ENOENT is returned
d7468609ee0f90 Christoph Hellwig 2024-02-19 2374 * - for all other flags a new folio is allocated, inserted into the
d7468609ee0f90 Christoph Hellwig 2024-02-19 2375 * page cache and returned locked in @foliop.
d7468609ee0f90 Christoph Hellwig 2024-02-19 2376 *
d7468609ee0f90 Christoph Hellwig 2024-02-19 2377 * Context: May sleep.
d7468609ee0f90 Christoph Hellwig 2024-02-19 2378 * Return: 0 if successful, else a negative error code.
d7468609ee0f90 Christoph Hellwig 2024-02-19 2379 */
4e1fc793ad9892 Matthew Wilcox (Oracle 2022-09-02 2380) int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
02efe2fbe45ffd Daniel Gomez 2024-05-15 2381 enum sgp_type sgp, size_t len)
4e1fc793ad9892 Matthew Wilcox (Oracle 2022-09-02 @2382) {
4e1fc793ad9892 Matthew Wilcox (Oracle 2022-09-02 2383) return shmem_get_folio_gfp(inode, index, foliop, sgp,
02efe2fbe45ffd Daniel Gomez 2024-05-15 2384 mapping_gfp_mask(inode->i_mapping), NULL, NULL, len);
4e1fc793ad9892 Matthew Wilcox (Oracle 2022-09-02 2385) }
d7468609ee0f90 Christoph Hellwig 2024-02-19 2386 EXPORT_SYMBOL_GPL(shmem_get_folio);
4e1fc793ad9892 Matthew Wilcox (Oracle 2022-09-02 2387)

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

2024-05-17 16:18:46

by Darrick J. Wong

Subject: Re: [PATCH 11/12] shmem: add file length arg in shmem_get_folio() path

On Wed, May 15, 2024 at 05:57:36AM +0000, Daniel Gomez wrote:
> In preparation for large folio in the write and fallocate paths, add
> file length argument in shmem_get_folio() path to be able to calculate
> the folio order based on the file size. Use of order-0 (PAGE_SIZE) for
> read, page cache read, and vm fault.
>
> This enables high order folios in the write and fallocate path once the
> folio order is calculated based on the length.
>
> Signed-off-by: Daniel Gomez <[email protected]>
> ---
> fs/xfs/scrub/xfile.c | 6 +++---
> fs/xfs/xfs_buf_mem.c | 3 ++-
> include/linux/shmem_fs.h | 2 +-
> mm/khugepaged.c | 3 ++-
> mm/shmem.c | 35 ++++++++++++++++++++---------------
> mm/userfaultfd.c | 2 +-
> 6 files changed, 29 insertions(+), 22 deletions(-)
>
> diff --git a/fs/xfs/scrub/xfile.c b/fs/xfs/scrub/xfile.c
> index 8cdd863db585..4905f5e4cb5d 100644
> --- a/fs/xfs/scrub/xfile.c
> +++ b/fs/xfs/scrub/xfile.c
> @@ -127,7 +127,7 @@ xfile_load(
> unsigned int offset;
>
> if (shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
> - SGP_READ) < 0)
> + SGP_READ, PAGE_SIZE) < 0)

I suppose I /did/ say during LSFMM that for the current users of xfile.c
and xfs_buf_mem.c the order of the folio being returned doesn't really
matter, but why wouldn't the last argument here be "roundup_64(count,
PAGE_SIZE)" ? Shouldn't we at least hint to the page cache about the
folio order that we actually want instead of limiting it to order-0?

(Also it seems a little odd to me that the @index is in units of pgoff_t
but @len is in bytes.)

> break;
> if (!folio) {
> /*
> @@ -197,7 +197,7 @@ xfile_store(
> unsigned int offset;
>
> if (shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
> - SGP_CACHE) < 0)
> + SGP_CACHE, PAGE_SIZE) < 0)
> break;
> if (filemap_check_wb_err(inode->i_mapping, 0)) {
> folio_unlock(folio);
> @@ -268,7 +268,7 @@ xfile_get_folio(
>
> pflags = memalloc_nofs_save();
> error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
> - (flags & XFILE_ALLOC) ? SGP_CACHE : SGP_READ);
> + (flags & XFILE_ALLOC) ? SGP_CACHE : SGP_READ, PAGE_SIZE);
> memalloc_nofs_restore(pflags);
> if (error)
> return ERR_PTR(error);
> diff --git a/fs/xfs/xfs_buf_mem.c b/fs/xfs/xfs_buf_mem.c
> index 9bb2d24de709..784c81d35a1f 100644
> --- a/fs/xfs/xfs_buf_mem.c
> +++ b/fs/xfs/xfs_buf_mem.c
> @@ -149,7 +149,8 @@ xmbuf_map_page(
> return -ENOMEM;
> }
>
> - error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio, SGP_CACHE);
> + error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio, SGP_CACHE,
> + PAGE_SIZE);

This is ok unless someone wants to use a different XMBUF_BLOCKSIZE.

--D

> if (error)
> return error;
>
> diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> index 3fb18f7eb73e..bc59b4a00228 100644
> --- a/include/linux/shmem_fs.h
> +++ b/include/linux/shmem_fs.h
> @@ -142,7 +142,7 @@ enum sgp_type {
> };
>
> int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
> - enum sgp_type sgp);
> + enum sgp_type sgp, size_t len);
> struct folio *shmem_read_folio_gfp(struct address_space *mapping,
> pgoff_t index, gfp_t gfp);
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 38830174608f..947770ded68c 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -1863,7 +1863,8 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
> xas_unlock_irq(&xas);
> /* swap in or instantiate fallocated page */
> if (shmem_get_folio(mapping->host, index,
> - &folio, SGP_NOALLOC)) {
> + &folio, SGP_NOALLOC,
> + PAGE_SIZE)) {
> result = SCAN_FAIL;
> goto xa_unlocked;
> }
> diff --git a/mm/shmem.c b/mm/shmem.c
> index d531018ffece..fcd2c9befe19 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1134,7 +1134,7 @@ static struct folio *shmem_get_partial_folio(struct inode *inode, pgoff_t index)
> * (although in some cases this is just a waste of time).
> */
> folio = NULL;
> - shmem_get_folio(inode, index, &folio, SGP_READ);
> + shmem_get_folio(inode, index, &folio, SGP_READ, PAGE_SIZE);
> return folio;
> }
>
> @@ -1844,7 +1844,7 @@ static struct folio *shmem_alloc_folio(gfp_t gfp, struct shmem_inode_info *info,
>
> static struct folio *shmem_alloc_and_add_folio(gfp_t gfp,
> struct inode *inode, pgoff_t index,
> - struct mm_struct *fault_mm, bool huge)
> + struct mm_struct *fault_mm, bool huge, size_t len)
> {
> struct address_space *mapping = inode->i_mapping;
> struct shmem_inode_info *info = SHMEM_I(inode);
> @@ -2173,7 +2173,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
> */
> static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> struct folio **foliop, enum sgp_type sgp, gfp_t gfp,
> - struct vm_fault *vmf, vm_fault_t *fault_type)
> + struct vm_fault *vmf, vm_fault_t *fault_type, size_t len)
> {
> struct vm_area_struct *vma = vmf ? vmf->vma : NULL;
> struct mm_struct *fault_mm;
> @@ -2258,7 +2258,7 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> huge_gfp = vma_thp_gfp_mask(vma);
> huge_gfp = limit_gfp_mask(huge_gfp, gfp);
> folio = shmem_alloc_and_add_folio(huge_gfp,
> - inode, index, fault_mm, true);
> + inode, index, fault_mm, true, len);
> if (!IS_ERR(folio)) {
> count_vm_event(THP_FILE_ALLOC);
> goto alloced;
> @@ -2267,7 +2267,8 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> goto repeat;
> }
>
> - folio = shmem_alloc_and_add_folio(gfp, inode, index, fault_mm, false);
> + folio = shmem_alloc_and_add_folio(gfp, inode, index, fault_mm, false,
> + len);
> if (IS_ERR(folio)) {
> error = PTR_ERR(folio);
> if (error == -EEXIST)
> @@ -2377,10 +2378,10 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> * Return: 0 if successful, else a negative error code.
> */
> int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
> - enum sgp_type sgp)
> + enum sgp_type sgp, size_t len)
> {
> return shmem_get_folio_gfp(inode, index, foliop, sgp,
> - mapping_gfp_mask(inode->i_mapping), NULL, NULL);
> + mapping_gfp_mask(inode->i_mapping), NULL, NULL, len);
> }
> EXPORT_SYMBOL_GPL(shmem_get_folio);
>
> @@ -2475,7 +2476,7 @@ static vm_fault_t shmem_fault(struct vm_fault *vmf)
>
> WARN_ON_ONCE(vmf->page != NULL);
> err = shmem_get_folio_gfp(inode, vmf->pgoff, &folio, SGP_CACHE,
> - gfp, vmf, &ret);
> + gfp, vmf, &ret, PAGE_SIZE);
> if (err)
> return vmf_error(err);
> if (folio) {
> @@ -2954,6 +2955,9 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
> struct folio *folio;
> int ret = 0;
>
> + if (!mapping_large_folio_support(mapping))
> + len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));
> +
> /* i_rwsem is held by caller */
> if (unlikely(info->seals & (F_SEAL_GROW |
> F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
> @@ -2963,7 +2967,7 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
> return -EPERM;
> }
>
> - ret = shmem_get_folio(inode, index, &folio, SGP_WRITE);
> + ret = shmem_get_folio(inode, index, &folio, SGP_WRITE, len);
> if (ret)
> return ret;
>
> @@ -3083,7 +3087,7 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
> break;
> }
>
> - error = shmem_get_folio(inode, index, &folio, SGP_READ);
> + error = shmem_get_folio(inode, index, &folio, SGP_READ, PAGE_SIZE);
> if (error) {
> if (error == -EINVAL)
> error = 0;
> @@ -3260,7 +3264,7 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
> break;
>
> error = shmem_get_folio(inode, *ppos / PAGE_SIZE, &folio,
> - SGP_READ);
> + SGP_READ, PAGE_SIZE);
> if (error) {
> if (error == -EINVAL)
> error = 0;
> @@ -3469,7 +3473,8 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
> error = -ENOMEM;
> else
> error = shmem_get_folio(inode, index, &folio,
> - SGP_FALLOC);
> + SGP_FALLOC,
> + (end - index) << PAGE_SHIFT);
> if (error) {
> info->fallocend = undo_fallocend;
> /* Remove the !uptodate folios we added */
> @@ -3822,7 +3827,7 @@ static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir,
> } else {
> inode_nohighmem(inode);
> inode->i_mapping->a_ops = &shmem_aops;
> - error = shmem_get_folio(inode, 0, &folio, SGP_WRITE);
> + error = shmem_get_folio(inode, 0, &folio, SGP_WRITE, PAGE_SIZE);
> if (error)
> goto out_remove_offset;
> inode->i_op = &shmem_symlink_inode_operations;
> @@ -3868,7 +3873,7 @@ static const char *shmem_get_link(struct dentry *dentry, struct inode *inode,
> return ERR_PTR(-ECHILD);
> }
> } else {
> - error = shmem_get_folio(inode, 0, &folio, SGP_READ);
> + error = shmem_get_folio(inode, 0, &folio, SGP_READ, PAGE_SIZE);
> if (error)
> return ERR_PTR(error);
> if (!folio)
> @@ -5255,7 +5260,7 @@ struct folio *shmem_read_folio_gfp(struct address_space *mapping,
> int error;
>
> error = shmem_get_folio_gfp(inode, index, &folio, SGP_CACHE,
> - gfp, NULL, NULL);
> + gfp, NULL, NULL, PAGE_SIZE);
> if (error)
> return ERR_PTR(error);
>
> diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> index 3c3539c573e7..540a0c2d4325 100644
> --- a/mm/userfaultfd.c
> +++ b/mm/userfaultfd.c
> @@ -359,7 +359,7 @@ static int mfill_atomic_pte_continue(pmd_t *dst_pmd,
> struct page *page;
> int ret;
>
> - ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC);
> + ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC, PAGE_SIZE);
> /* Our caller expects us to return -EFAULT if we failed to find folio */
> if (ret == -ENOENT)
> ret = -EFAULT;
> --
> 2.43.0
>

2024-05-21 11:42:01

by Daniel Gomez

Subject: Re: [PATCH 11/12] shmem: add file length arg in shmem_get_folio() path

On Fri, May 17, 2024 at 09:17:41AM -0700, Darrick J. Wong wrote:
> On Wed, May 15, 2024 at 05:57:36AM +0000, Daniel Gomez wrote:
> > In preparation for large folio in the write and fallocate paths, add
> > file length argument in shmem_get_folio() path to be able to calculate
> > the folio order based on the file size. Use of order-0 (PAGE_SIZE) for
> > read, page cache read, and vm fault.
> >
> > This enables high order folios in the write and fallocate path once the
> > folio order is calculated based on the length.
> >
> > Signed-off-by: Daniel Gomez <[email protected]>
> > ---
> > fs/xfs/scrub/xfile.c | 6 +++---
> > fs/xfs/xfs_buf_mem.c | 3 ++-
> > include/linux/shmem_fs.h | 2 +-
> > mm/khugepaged.c | 3 ++-
> > mm/shmem.c | 35 ++++++++++++++++++++---------------
> > mm/userfaultfd.c | 2 +-
> > 6 files changed, 29 insertions(+), 22 deletions(-)
> >
> > diff --git a/fs/xfs/scrub/xfile.c b/fs/xfs/scrub/xfile.c
> > index 8cdd863db585..4905f5e4cb5d 100644
> > --- a/fs/xfs/scrub/xfile.c
> > +++ b/fs/xfs/scrub/xfile.c
> > @@ -127,7 +127,7 @@ xfile_load(
> > unsigned int offset;
> >
> > if (shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
> > - SGP_READ) < 0)
> > + SGP_READ, PAGE_SIZE) < 0)
>
> I suppose I /did/ say during LSFMM that for the current users of xfile.c
> and xfs_buf_mem.c the order of the folio being returned doesn't really
I not sure if I understood you well. Could you please elaborate on this?

> matter, but why wouldn't the last argument here be "roundup_64(count,
> PAGE_SIZE)" ? Shouldn't we at least hint to the page cache about the
> folio order that we actually want instead of limiting it to order-0?

For v2, I'll include your suggestions. I think we can also enable large folios
in xfile_get_folio(), please check below:

diff --git a/fs/xfs/scrub/xfile.c b/fs/xfs/scrub/xfile.c
index 8cdd863db585..df8b495b4939 100644
--- a/fs/xfs/scrub/xfile.c
+++ b/fs/xfs/scrub/xfile.c
@@ -127,7 +127,7 @@ xfile_load(
unsigned int offset;

if (shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
- SGP_READ) < 0)
+ SGP_READ, roundup_64(count, PAGE_SIZE)) < 0)
break;
if (!folio) {
/*
@@ -197,7 +197,7 @@ xfile_store(
unsigned int offset;

if (shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
- SGP_CACHE) < 0)
+ SGP_CACHE, roundup_64(count, PAGE_SIZE)) < 0)
break;
if (filemap_check_wb_err(inode->i_mapping, 0)) {
folio_unlock(folio);
@@ -268,7 +268,8 @@ xfile_get_folio(

pflags = memalloc_nofs_save();
error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
- (flags & XFILE_ALLOC) ? SGP_CACHE : SGP_READ);
+ (flags & XFILE_ALLOC) ? SGP_CACHE : SGP_READ,
+ roundup_64(i_size_read(inode), PAGE_SIZE));
memalloc_nofs_restore(pflags);
if (error)
return ERR_PTR(error);

>
> (Also it seems a little odd to me that the @index is in units of pgoff_t
> but @len is in bytes.)

I extended the shmem_get_folio() with @len to calculate folio order based on
size (bytes). This is sent to ilog2() although I'm planning to use get_order()
instead (after fixing the issues mentioned during the discussion). @index is
used for __ffs() (same as in filemap).

Would you use lofft for @len instead? Or what's your suggestion?

Thanks,
Daniel

>
> > break;
> > if (!folio) {
> > /*
> > @@ -197,7 +197,7 @@ xfile_store(
> > unsigned int offset;
> >
> > if (shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
> > - SGP_CACHE) < 0)
> > + SGP_CACHE, PAGE_SIZE) < 0)
> > break;
> > if (filemap_check_wb_err(inode->i_mapping, 0)) {
> > folio_unlock(folio);
> > @@ -268,7 +268,7 @@ xfile_get_folio(
> >
> > pflags = memalloc_nofs_save();
> > error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
> > - (flags & XFILE_ALLOC) ? SGP_CACHE : SGP_READ);
> > + (flags & XFILE_ALLOC) ? SGP_CACHE : SGP_READ, PAGE_SIZE);
> > memalloc_nofs_restore(pflags);
> > if (error)
> > return ERR_PTR(error);
> > diff --git a/fs/xfs/xfs_buf_mem.c b/fs/xfs/xfs_buf_mem.c
> > index 9bb2d24de709..784c81d35a1f 100644
> > --- a/fs/xfs/xfs_buf_mem.c
> > +++ b/fs/xfs/xfs_buf_mem.c
> > @@ -149,7 +149,8 @@ xmbuf_map_page(
> > return -ENOMEM;
> > }
> >
> > - error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio, SGP_CACHE);
> > + error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio, SGP_CACHE,
> > + PAGE_SIZE);
>
> This is ok unless someone wants to use a different XMBUF_BLOCKSIZE.
>
> --D
>
> > if (error)
> > return error;
> >
> > diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> > index 3fb18f7eb73e..bc59b4a00228 100644
> > --- a/include/linux/shmem_fs.h
> > +++ b/include/linux/shmem_fs.h
> > @@ -142,7 +142,7 @@ enum sgp_type {
> > };
> >
> > int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
> > - enum sgp_type sgp);
> > + enum sgp_type sgp, size_t len);
> > struct folio *shmem_read_folio_gfp(struct address_space *mapping,
> > pgoff_t index, gfp_t gfp);
> >
> > diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> > index 38830174608f..947770ded68c 100644
> > --- a/mm/khugepaged.c
> > +++ b/mm/khugepaged.c
> > @@ -1863,7 +1863,8 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
> > xas_unlock_irq(&xas);
> > /* swap in or instantiate fallocated page */
> > if (shmem_get_folio(mapping->host, index,
> > - &folio, SGP_NOALLOC)) {
> > + &folio, SGP_NOALLOC,
> > + PAGE_SIZE)) {
> > result = SCAN_FAIL;
> > goto xa_unlocked;
> > }
> > diff --git a/mm/shmem.c b/mm/shmem.c
> > index d531018ffece..fcd2c9befe19 100644
> > --- a/mm/shmem.c
> > +++ b/mm/shmem.c
> > @@ -1134,7 +1134,7 @@ static struct folio *shmem_get_partial_folio(struct inode *inode, pgoff_t index)
> > * (although in some cases this is just a waste of time).
> > */
> > folio = NULL;
> > - shmem_get_folio(inode, index, &folio, SGP_READ);
> > + shmem_get_folio(inode, index, &folio, SGP_READ, PAGE_SIZE);
> > return folio;
> > }
> >
> > @@ -1844,7 +1844,7 @@ static struct folio *shmem_alloc_folio(gfp_t gfp, struct shmem_inode_info *info,
> >
> > static struct folio *shmem_alloc_and_add_folio(gfp_t gfp,
> > struct inode *inode, pgoff_t index,
> > - struct mm_struct *fault_mm, bool huge)
> > + struct mm_struct *fault_mm, bool huge, size_t len)
> > {
> > struct address_space *mapping = inode->i_mapping;
> > struct shmem_inode_info *info = SHMEM_I(inode);
> > @@ -2173,7 +2173,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
> > */
> > static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> > struct folio **foliop, enum sgp_type sgp, gfp_t gfp,
> > - struct vm_fault *vmf, vm_fault_t *fault_type)
> > + struct vm_fault *vmf, vm_fault_t *fault_type, size_t len)
> > {
> > struct vm_area_struct *vma = vmf ? vmf->vma : NULL;
> > struct mm_struct *fault_mm;
> > @@ -2258,7 +2258,7 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> > huge_gfp = vma_thp_gfp_mask(vma);
> > huge_gfp = limit_gfp_mask(huge_gfp, gfp);
> > folio = shmem_alloc_and_add_folio(huge_gfp,
> > - inode, index, fault_mm, true);
> > + inode, index, fault_mm, true, len);
> > if (!IS_ERR(folio)) {
> > count_vm_event(THP_FILE_ALLOC);
> > goto alloced;
> > @@ -2267,7 +2267,8 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> > goto repeat;
> > }
> >
> > - folio = shmem_alloc_and_add_folio(gfp, inode, index, fault_mm, false);
> > + folio = shmem_alloc_and_add_folio(gfp, inode, index, fault_mm, false,
> > + len);
> > if (IS_ERR(folio)) {
> > error = PTR_ERR(folio);
> > if (error == -EEXIST)
> > @@ -2377,10 +2378,10 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> > * Return: 0 if successful, else a negative error code.
> > */
> > int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
> > - enum sgp_type sgp)
> > + enum sgp_type sgp, size_t len)
> > {
> > return shmem_get_folio_gfp(inode, index, foliop, sgp,
> > - mapping_gfp_mask(inode->i_mapping), NULL, NULL);
> > + mapping_gfp_mask(inode->i_mapping), NULL, NULL, len);
> > }
> > EXPORT_SYMBOL_GPL(shmem_get_folio);
> >
> > @@ -2475,7 +2476,7 @@ static vm_fault_t shmem_fault(struct vm_fault *vmf)
> >
> > WARN_ON_ONCE(vmf->page != NULL);
> > err = shmem_get_folio_gfp(inode, vmf->pgoff, &folio, SGP_CACHE,
> > - gfp, vmf, &ret);
> > + gfp, vmf, &ret, PAGE_SIZE);
> > if (err)
> > return vmf_error(err);
> > if (folio) {
> > @@ -2954,6 +2955,9 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
> > struct folio *folio;
> > int ret = 0;
> >
> > + if (!mapping_large_folio_support(mapping))
> > + len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));
> > +
> > /* i_rwsem is held by caller */
> > if (unlikely(info->seals & (F_SEAL_GROW |
> > F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
> > @@ -2963,7 +2967,7 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
> > return -EPERM;
> > }
> >
> > - ret = shmem_get_folio(inode, index, &folio, SGP_WRITE);
> > + ret = shmem_get_folio(inode, index, &folio, SGP_WRITE, len);
> > if (ret)
> > return ret;
> >
> > @@ -3083,7 +3087,7 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
> > break;
> > }
> >
> > - error = shmem_get_folio(inode, index, &folio, SGP_READ);
> > + error = shmem_get_folio(inode, index, &folio, SGP_READ, PAGE_SIZE);
> > if (error) {
> > if (error == -EINVAL)
> > error = 0;
> > @@ -3260,7 +3264,7 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
> > break;
> >
> > error = shmem_get_folio(inode, *ppos / PAGE_SIZE, &folio,
> > - SGP_READ);
> > + SGP_READ, PAGE_SIZE);
> > if (error) {
> > if (error == -EINVAL)
> > error = 0;
> > @@ -3469,7 +3473,8 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
> > error = -ENOMEM;
> > else
> > error = shmem_get_folio(inode, index, &folio,
> > - SGP_FALLOC);
> > + SGP_FALLOC,
> > + (end - index) << PAGE_SHIFT);
> > if (error) {
> > info->fallocend = undo_fallocend;
> > /* Remove the !uptodate folios we added */
> > @@ -3822,7 +3827,7 @@ static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir,
> > } else {
> > inode_nohighmem(inode);
> > inode->i_mapping->a_ops = &shmem_aops;
> > - error = shmem_get_folio(inode, 0, &folio, SGP_WRITE);
> > + error = shmem_get_folio(inode, 0, &folio, SGP_WRITE, PAGE_SIZE);
> > if (error)
> > goto out_remove_offset;
> > inode->i_op = &shmem_symlink_inode_operations;
> > @@ -3868,7 +3873,7 @@ static const char *shmem_get_link(struct dentry *dentry, struct inode *inode,
> > return ERR_PTR(-ECHILD);
> > }
> > } else {
> > - error = shmem_get_folio(inode, 0, &folio, SGP_READ);
> > + error = shmem_get_folio(inode, 0, &folio, SGP_READ, PAGE_SIZE);
> > if (error)
> > return ERR_PTR(error);
> > if (!folio)
> > @@ -5255,7 +5260,7 @@ struct folio *shmem_read_folio_gfp(struct address_space *mapping,
> > int error;
> >
> > error = shmem_get_folio_gfp(inode, index, &folio, SGP_CACHE,
> > - gfp, NULL, NULL);
> > + gfp, NULL, NULL, PAGE_SIZE);
> > if (error)
> > return ERR_PTR(error);
> >
> > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> > index 3c3539c573e7..540a0c2d4325 100644
> > --- a/mm/userfaultfd.c
> > +++ b/mm/userfaultfd.c
> > @@ -359,7 +359,7 @@ static int mfill_atomic_pte_continue(pmd_t *dst_pmd,
> > struct page *page;
> > int ret;
> >
> > - ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC);
> > + ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC, PAGE_SIZE);
> > /* Our caller expects us to return -EFAULT if we failed to find folio */
> > if (ret == -ENOENT)
> > ret = -EFAULT;
> > --
> > 2.43.0
> >

2024-05-21 16:39:47

by Darrick J. Wong

Subject: Re: [PATCH 11/12] shmem: add file length arg in shmem_get_folio() path

On Tue, May 21, 2024 at 11:38:33AM +0000, Daniel Gomez wrote:
> On Fri, May 17, 2024 at 09:17:41AM -0700, Darrick J. Wong wrote:
> > On Wed, May 15, 2024 at 05:57:36AM +0000, Daniel Gomez wrote:
> > > In preparation for large folio in the write and fallocate paths, add
> > > file length argument in shmem_get_folio() path to be able to calculate
> > > the folio order based on the file size. Use of order-0 (PAGE_SIZE) for
> > > read, page cache read, and vm fault.
> > >
> > > This enables high order folios in the write and fallocate path once the
> > > folio order is calculated based on the length.
> > >
> > > Signed-off-by: Daniel Gomez <[email protected]>
> > > ---
> > > fs/xfs/scrub/xfile.c | 6 +++---
> > > fs/xfs/xfs_buf_mem.c | 3 ++-
> > > include/linux/shmem_fs.h | 2 +-
> > > mm/khugepaged.c | 3 ++-
> > > mm/shmem.c | 35 ++++++++++++++++++++---------------
> > > mm/userfaultfd.c | 2 +-
> > > 6 files changed, 29 insertions(+), 22 deletions(-)
> > >
> > > diff --git a/fs/xfs/scrub/xfile.c b/fs/xfs/scrub/xfile.c
> > > index 8cdd863db585..4905f5e4cb5d 100644
> > > --- a/fs/xfs/scrub/xfile.c
> > > +++ b/fs/xfs/scrub/xfile.c
> > > @@ -127,7 +127,7 @@ xfile_load(
> > > unsigned int offset;
> > >
> > > if (shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
> > > - SGP_READ) < 0)
> > > + SGP_READ, PAGE_SIZE) < 0)
> >
> > I suppose I /did/ say during LSFMM that for the current users of xfile.c
> > and xfs_buf_mem.c the order of the folio being returned doesn't really
> I not sure if I understood you well. Could you please elaborate on this?

Yes, I'll restate what I said in the session last week for those who
weren't there:

Currently, xfile.c and xfs_buf_mem.c are only used by online repair to
stage a recordset while rebuilding an ondisk btree index. IOWs, they're
ephemeral, so we don't care or need to optimize folio sizing. Some day
they might be adapted for longer-term usage though, so we might as well
try not to leave too many papercuts.

xfs_buf_mem.c creates in-memory btrees that mimic the ondisk btrees,
albeit with blocksize == PAGE_SIZE, regardless of the fs blocksize.
For this case we probably aren't ever going to care about large folios.

xfile.c is currently used to store fixed-size recordsets, names for
rebuilding directories, and name/value pairs for rebuilding xattr
structures. Records aren't allowed to be larger than PAGE_SIZE, names
cannot be larger than MAXNAMELEN (255), and xattr values can't be larger
than 64k.

For that last case maybe it might be nice to get a large folio to reduce
processing overhead, but huge xattrs aren't that common.

> > matter, but why wouldn't the last argument here be "roundup_64(count,
> > PAGE_SIZE)" ? Shouldn't we at least hint to the page cache about the
> > folio order that we actually want instead of limiting it to order-0?
>
> For v2, I'll include your suggestions. I think we can also enable large folios
> in xfile_get_folio(), please check below:
>
> diff --git a/fs/xfs/scrub/xfile.c b/fs/xfs/scrub/xfile.c
> index 8cdd863db585..df8b495b4939 100644
> --- a/fs/xfs/scrub/xfile.c
> +++ b/fs/xfs/scrub/xfile.c
> @@ -127,7 +127,7 @@ xfile_load(
> unsigned int offset;
>
> if (shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
> - SGP_READ) < 0)
> + SGP_READ, roundup_64(count, PAGE_SIZE)) < 0)
> break;
> if (!folio) {
> /*
> @@ -197,7 +197,7 @@ xfile_store(
> unsigned int offset;
>
> if (shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
> - SGP_CACHE) < 0)
> + SGP_CACHE, roundup_64(count, PAGE_SIZE)) < 0)
> break;
> if (filemap_check_wb_err(inode->i_mapping, 0)) {
> folio_unlock(folio);
> @@ -268,7 +268,8 @@ xfile_get_folio(
>
> pflags = memalloc_nofs_save();
> error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
> - (flags & XFILE_ALLOC) ? SGP_CACHE : SGP_READ);
> + (flags & XFILE_ALLOC) ? SGP_CACHE : SGP_READ,
> + roundup_64(i_size_read(inode), PAGE_SIZE));

I'm not sure why you picked i_size_read here; the xfile could be several
gigabytes long. xfile_get_folio want to look at a subset of the xfile,
not all of it.

roundup_64(len, PAGE_SIZE) perhaps?

Also, should the rounding be done inside the shmem code so that callers
don't have to know about that detail?

> memalloc_nofs_restore(pflags);
> if (error)
> return ERR_PTR(error);
>
> >
> > (Also it seems a little odd to me that the @index is in units of pgoff_t
> > but @len is in bytes.)
>
> I extended the shmem_get_folio() with @len to calculate folio order based on
> size (bytes). This is sent to ilog2() although I'm planning to use get_order()
> instead (after fixing the issues mentioned during the discussion). @index is
> used for __ffs() (same as in filemap).
>
> Would you use lofft for @len instead? Or what's your suggestion?

I was reacting to @index, not @len. I might've shifted @index to
"loff_t pos" but looking at the existing callsites it doesn't seem worth
the churn.

--D

> Thanks,
> Daniel
>
> >
> > > break;
> > > if (!folio) {
> > > /*
> > > @@ -197,7 +197,7 @@ xfile_store(
> > > unsigned int offset;
> > >
> > > if (shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
> > > - SGP_CACHE) < 0)
> > > + SGP_CACHE, PAGE_SIZE) < 0)
> > > break;
> > > if (filemap_check_wb_err(inode->i_mapping, 0)) {
> > > folio_unlock(folio);
> > > @@ -268,7 +268,7 @@ xfile_get_folio(
> > >
> > > pflags = memalloc_nofs_save();
> > > error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio,
> > > - (flags & XFILE_ALLOC) ? SGP_CACHE : SGP_READ);
> > > + (flags & XFILE_ALLOC) ? SGP_CACHE : SGP_READ, PAGE_SIZE);
> > > memalloc_nofs_restore(pflags);
> > > if (error)
> > > return ERR_PTR(error);
> > > diff --git a/fs/xfs/xfs_buf_mem.c b/fs/xfs/xfs_buf_mem.c
> > > index 9bb2d24de709..784c81d35a1f 100644
> > > --- a/fs/xfs/xfs_buf_mem.c
> > > +++ b/fs/xfs/xfs_buf_mem.c
> > > @@ -149,7 +149,8 @@ xmbuf_map_page(
> > > return -ENOMEM;
> > > }
> > >
> > > - error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio, SGP_CACHE);
> > > + error = shmem_get_folio(inode, pos >> PAGE_SHIFT, &folio, SGP_CACHE,
> > > + PAGE_SIZE);
> >
> > This is ok unless someone wants to use a different XMBUF_BLOCKSIZE.
> >
> > --D
> >
> > > if (error)
> > > return error;
> > >
> > > diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> > > index 3fb18f7eb73e..bc59b4a00228 100644
> > > --- a/include/linux/shmem_fs.h
> > > +++ b/include/linux/shmem_fs.h
> > > @@ -142,7 +142,7 @@ enum sgp_type {
> > > };
> > >
> > > int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
> > > - enum sgp_type sgp);
> > > + enum sgp_type sgp, size_t len);
> > > struct folio *shmem_read_folio_gfp(struct address_space *mapping,
> > > pgoff_t index, gfp_t gfp);
> > >
> > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> > > index 38830174608f..947770ded68c 100644
> > > --- a/mm/khugepaged.c
> > > +++ b/mm/khugepaged.c
> > > @@ -1863,7 +1863,8 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
> > > xas_unlock_irq(&xas);
> > > /* swap in or instantiate fallocated page */
> > > if (shmem_get_folio(mapping->host, index,
> > > - &folio, SGP_NOALLOC)) {
> > > + &folio, SGP_NOALLOC,
> > > + PAGE_SIZE)) {
> > > result = SCAN_FAIL;
> > > goto xa_unlocked;
> > > }
> > > diff --git a/mm/shmem.c b/mm/shmem.c
> > > index d531018ffece..fcd2c9befe19 100644
> > > --- a/mm/shmem.c
> > > +++ b/mm/shmem.c
> > > @@ -1134,7 +1134,7 @@ static struct folio *shmem_get_partial_folio(struct inode *inode, pgoff_t index)
> > > * (although in some cases this is just a waste of time).
> > > */
> > > folio = NULL;
> > > - shmem_get_folio(inode, index, &folio, SGP_READ);
> > > + shmem_get_folio(inode, index, &folio, SGP_READ, PAGE_SIZE);
> > > return folio;
> > > }
> > >
> > > @@ -1844,7 +1844,7 @@ static struct folio *shmem_alloc_folio(gfp_t gfp, struct shmem_inode_info *info,
> > >
> > > static struct folio *shmem_alloc_and_add_folio(gfp_t gfp,
> > > struct inode *inode, pgoff_t index,
> > > - struct mm_struct *fault_mm, bool huge)
> > > + struct mm_struct *fault_mm, bool huge, size_t len)
> > > {
> > > struct address_space *mapping = inode->i_mapping;
> > > struct shmem_inode_info *info = SHMEM_I(inode);
> > > @@ -2173,7 +2173,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
> > > */
> > > static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> > > struct folio **foliop, enum sgp_type sgp, gfp_t gfp,
> > > - struct vm_fault *vmf, vm_fault_t *fault_type)
> > > + struct vm_fault *vmf, vm_fault_t *fault_type, size_t len)
> > > {
> > > struct vm_area_struct *vma = vmf ? vmf->vma : NULL;
> > > struct mm_struct *fault_mm;
> > > @@ -2258,7 +2258,7 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> > > huge_gfp = vma_thp_gfp_mask(vma);
> > > huge_gfp = limit_gfp_mask(huge_gfp, gfp);
> > > folio = shmem_alloc_and_add_folio(huge_gfp,
> > > - inode, index, fault_mm, true);
> > > + inode, index, fault_mm, true, len);
> > > if (!IS_ERR(folio)) {
> > > count_vm_event(THP_FILE_ALLOC);
> > > goto alloced;
> > > @@ -2267,7 +2267,8 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> > > goto repeat;
> > > }
> > >
> > > - folio = shmem_alloc_and_add_folio(gfp, inode, index, fault_mm, false);
> > > + folio = shmem_alloc_and_add_folio(gfp, inode, index, fault_mm, false,
> > > + len);
> > > if (IS_ERR(folio)) {
> > > error = PTR_ERR(folio);
> > > if (error == -EEXIST)
> > > @@ -2377,10 +2378,10 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> > > * Return: 0 if successful, else a negative error code.
> > > */
> > > int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
> > > - enum sgp_type sgp)
> > > + enum sgp_type sgp, size_t len)
> > > {
> > > return shmem_get_folio_gfp(inode, index, foliop, sgp,
> > > - mapping_gfp_mask(inode->i_mapping), NULL, NULL);
> > > + mapping_gfp_mask(inode->i_mapping), NULL, NULL, len);
> > > }
> > > EXPORT_SYMBOL_GPL(shmem_get_folio);
> > >
> > > @@ -2475,7 +2476,7 @@ static vm_fault_t shmem_fault(struct vm_fault *vmf)
> > >
> > > WARN_ON_ONCE(vmf->page != NULL);
> > > err = shmem_get_folio_gfp(inode, vmf->pgoff, &folio, SGP_CACHE,
> > > - gfp, vmf, &ret);
> > > + gfp, vmf, &ret, PAGE_SIZE);
> > > if (err)
> > > return vmf_error(err);
> > > if (folio) {
> > > @@ -2954,6 +2955,9 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
> > > struct folio *folio;
> > > int ret = 0;
> > >
> > > + if (!mapping_large_folio_support(mapping))
> > > + len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));
> > > +
> > > /* i_rwsem is held by caller */
> > > if (unlikely(info->seals & (F_SEAL_GROW |
> > > F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
> > > @@ -2963,7 +2967,7 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
> > > return -EPERM;
> > > }
> > >
> > > - ret = shmem_get_folio(inode, index, &folio, SGP_WRITE);
> > > + ret = shmem_get_folio(inode, index, &folio, SGP_WRITE, len);
> > > if (ret)
> > > return ret;
> > >
> > > @@ -3083,7 +3087,7 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
> > > break;
> > > }
> > >
> > > - error = shmem_get_folio(inode, index, &folio, SGP_READ);
> > > + error = shmem_get_folio(inode, index, &folio, SGP_READ, PAGE_SIZE);
> > > if (error) {
> > > if (error == -EINVAL)
> > > error = 0;
> > > @@ -3260,7 +3264,7 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
> > > break;
> > >
> > > error = shmem_get_folio(inode, *ppos / PAGE_SIZE, &folio,
> > > - SGP_READ);
> > > + SGP_READ, PAGE_SIZE);
> > > if (error) {
> > > if (error == -EINVAL)
> > > error = 0;
> > > @@ -3469,7 +3473,8 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
> > > error = -ENOMEM;
> > > else
> > > error = shmem_get_folio(inode, index, &folio,
> > > - SGP_FALLOC);
> > > + SGP_FALLOC,
> > > + (end - index) << PAGE_SHIFT);
> > > if (error) {
> > > info->fallocend = undo_fallocend;
> > > /* Remove the !uptodate folios we added */
> > > @@ -3822,7 +3827,7 @@ static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir,
> > > } else {
> > > inode_nohighmem(inode);
> > > inode->i_mapping->a_ops = &shmem_aops;
> > > - error = shmem_get_folio(inode, 0, &folio, SGP_WRITE);
> > > + error = shmem_get_folio(inode, 0, &folio, SGP_WRITE, PAGE_SIZE);
> > > if (error)
> > > goto out_remove_offset;
> > > inode->i_op = &shmem_symlink_inode_operations;
> > > @@ -3868,7 +3873,7 @@ static const char *shmem_get_link(struct dentry *dentry, struct inode *inode,
> > > return ERR_PTR(-ECHILD);
> > > }
> > > } else {
> > > - error = shmem_get_folio(inode, 0, &folio, SGP_READ);
> > > + error = shmem_get_folio(inode, 0, &folio, SGP_READ, PAGE_SIZE);
> > > if (error)
> > > return ERR_PTR(error);
> > > if (!folio)
> > > @@ -5255,7 +5260,7 @@ struct folio *shmem_read_folio_gfp(struct address_space *mapping,
> > > int error;
> > >
> > > error = shmem_get_folio_gfp(inode, index, &folio, SGP_CACHE,
> > > - gfp, NULL, NULL);
> > > + gfp, NULL, NULL, PAGE_SIZE);
> > > if (error)
> > > return ERR_PTR(error);
> > >
> > > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> > > index 3c3539c573e7..540a0c2d4325 100644
> > > --- a/mm/userfaultfd.c
> > > +++ b/mm/userfaultfd.c
> > > @@ -359,7 +359,7 @@ static int mfill_atomic_pte_continue(pmd_t *dst_pmd,
> > > struct page *page;
> > > int ret;
> > >
> > > - ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC);
> > > + ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC, PAGE_SIZE);
> > > /* Our caller expects us to return -EFAULT if we failed to find folio */
> > > if (ret == -ENOENT)
> > > ret = -EFAULT;
> > > --
> > > 2.43.0
> > >