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mm: return an ERR_PTR from __filemap_get_folio

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Instead of returning NULL for all errors, distinguish between:

 - no entry found and not asked to allocated (-ENOENT)
 - failed to allocate memory (-ENOMEM)
 - would block (-EAGAIN)

so that callers don't have to guess the error based on the passed in
flags.

Also pass through the error through the direct callers: filemap_get_folio,
filemap_lock_folio filemap_grab_folio and filemap_get_incore_folio.

[hch@lst.de: fix null-pointer deref]
  Link: https://lkml.kernel.org/r/20230310070023.GA13563@lst.de
  Link: https://lkml.kernel.org/r/20230310043137.GA1624890@u2004
Link: https://lkml.kernel.org/r/20230307143410.28031-8-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com> [nilfs2]
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Christoph Hellwig 2023-03-07 15:34:10 +01:00 committed by Andrew Morton
parent 48c9d11375
commit 66dabbb65d
21 changed files with 67 additions and 65 deletions
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10
fs/afs/dir.c
View file

@ -319,16 +319,16 @@ static struct afs_read *afs_read_dir(struct afs_vnode *dvnode, struct key *key)
struct folio *folio;
folio = filemap_get_folio(mapping, i);
if (!folio) {
if (IS_ERR(folio)) {
if (test_and_clear_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
afs_stat_v(dvnode, n_inval);
ret = -ENOMEM;
folio = __filemap_get_folio(mapping,
i, FGP_LOCK | FGP_CREAT,
mapping->gfp_mask);
if (!folio)
if (IS_ERR(folio)) {
ret = PTR_ERR(folio);
goto error;
}
folio_attach_private(folio, (void *)1);
folio_unlock(folio);
}
@ -524,7 +524,7 @@ static int afs_dir_iterate(struct inode *dir, struct dir_context *ctx,
*/
folio = __filemap_get_folio(dir->i_mapping, ctx->pos / PAGE_SIZE,
FGP_ACCESSED, 0);
if (!folio) {
if (IS_ERR(folio)) {
ret = afs_bad(dvnode, afs_file_error_dir_missing_page);
break;
}

2
fs/afs/dir_edit.c
View file

@ -115,7 +115,7 @@ static struct folio *afs_dir_get_folio(struct afs_vnode *vnode, pgoff_t index)
folio = __filemap_get_folio(mapping, index,
FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
mapping->gfp_mask);
if (!folio)
if (IS_ERR(folio))
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
else if (folio && !folio_test_private(folio))
folio_attach_private(folio, (void *)1);

4
fs/afs/write.c
View file

@ -232,7 +232,7 @@ static void afs_kill_pages(struct address_space *mapping,
_debug("kill %lx (to %lx)", index, last);
folio = filemap_get_folio(mapping, index);
if (!folio) {
if (IS_ERR(folio)) {
next = index + 1;
continue;
}
@ -270,7 +270,7 @@ static void afs_redirty_pages(struct writeback_control *wbc,
_debug("redirty %llx @%llx", len, start);
folio = filemap_get_folio(mapping, index);
if (!folio) {
if (IS_ERR(folio)) {
next = index + 1;
continue;
}

2
fs/ext4/inode.c
View file

@ -5395,7 +5395,7 @@ static void ext4_wait_for_tail_page_commit(struct inode *inode)
while (1) {
struct folio *folio = filemap_lock_folio(inode->i_mapping,
inode->i_size >> PAGE_SHIFT);
if (!folio)
if (IS_ERR(folio))
return;
ret = __ext4_journalled_invalidate_folio(folio, offset,
folio_size(folio) - offset);

8
fs/ext4/move_extent.c
View file

@ -141,18 +141,18 @@ mext_folio_double_lock(struct inode *inode1, struct inode *inode2,
flags = memalloc_nofs_save();
folio[0] = __filemap_get_folio(mapping[0], index1, fgp_flags,
mapping_gfp_mask(mapping[0]));
if (!folio[0]) {
if (IS_ERR(folio[0])) {
memalloc_nofs_restore(flags);
return -ENOMEM;
return PTR_ERR(folio[0]);
}
folio[1] = __filemap_get_folio(mapping[1], index2, fgp_flags,
mapping_gfp_mask(mapping[1]));
memalloc_nofs_restore(flags);
if (!folio[1]) {
if (IS_ERR(folio[1])) {
folio_unlock(folio[0]);
folio_put(folio[0]);
return -ENOMEM;
return PTR_ERR(folio[1]);
}
/*
* __filemap_get_folio() may not wait on folio's writeback if

2
fs/hugetlbfs/inode.c
View file

@ -697,7 +697,7 @@ static void hugetlbfs_zero_partial_page(struct hstate *h,
struct folio *folio;
folio = filemap_lock_folio(mapping, idx);
if (!folio)
if (IS_ERR(folio))
return;
start = start & ~huge_page_mask(h);

11
fs/iomap/buffered-io.c
View file

@ -468,19 +468,12 @@ EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos)
{
unsigned fgp = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE | FGP_NOFS;
struct folio *folio;
if (iter->flags & IOMAP_NOWAIT)
fgp |= FGP_NOWAIT;
folio = __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT,
return __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT,
fgp, mapping_gfp_mask(iter->inode->i_mapping));
if (folio)
return folio;
if (iter->flags & IOMAP_NOWAIT)
return ERR_PTR(-EAGAIN);
return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL_GPL(iomap_get_folio);
@ -911,7 +904,7 @@ static int iomap_write_delalloc_scan(struct inode *inode,
/* grab locked page */
folio = filemap_lock_folio(inode->i_mapping,
start_byte >> PAGE_SHIFT);
if (!folio) {
if (IS_ERR(folio)) {
start_byte = ALIGN_DOWN(start_byte, PAGE_SIZE) +
PAGE_SIZE;
continue;

4
fs/netfs/buffered_read.c
View file

@ -350,8 +350,8 @@ int netfs_write_begin(struct netfs_inode *ctx,
retry:
folio = __filemap_get_folio(mapping, index, fgp_flags,
mapping_gfp_mask(mapping));
if (!folio)
return -ENOMEM;
if (IS_ERR(folio))
return PTR_ERR(folio);
if (ctx->ops->check_write_begin) {
/* Allow the netfs (eg. ceph) to flush conflicts. */

4
fs/nfs/file.c
View file

@ -336,8 +336,8 @@ static int nfs_write_begin(struct file *file, struct address_space *mapping,
start:
folio = nfs_folio_grab_cache_write_begin(mapping, pos >> PAGE_SHIFT);
if (!folio)
return -ENOMEM;
if (IS_ERR(folio))
return PTR_ERR(folio);
*pagep = &folio->page;
ret = nfs_flush_incompatible(file, folio);

6
fs/nilfs2/page.c
View file

@ -259,10 +259,10 @@ int nilfs_copy_dirty_pages(struct address_space *dmap,
NILFS_PAGE_BUG(&folio->page, "inconsistent dirty state");
dfolio = filemap_grab_folio(dmap, folio->index);
if (unlikely(!dfolio)) {
if (unlikely(IS_ERR(dfolio))) {
/* No empty page is added to the page cache */
err = -ENOMEM;
folio_unlock(folio);
err = PTR_ERR(dfolio);
break;
}
if (unlikely(!folio_buffers(folio)))
@ -311,7 +311,7 @@ void nilfs_copy_back_pages(struct address_space *dmap,
folio_lock(folio);
dfolio = filemap_lock_folio(dmap, index);
if (dfolio) {
if (!IS_ERR(dfolio)) {
/* overwrite existing folio in the destination cache */
WARN_ON(folio_test_dirty(dfolio));
nilfs_copy_page(&dfolio->page, &folio->page, 0);

11
include/linux/pagemap.h
View file

@ -520,7 +520,8 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
* Looks up the page cache entry at @mapping & @index. If a folio is
* present, it is returned with an increased refcount.
*
* Otherwise, %NULL is returned.
* Return: A folio or ERR_PTR(-ENOENT) if there is no folio in the cache for
* this index. Will not return a shadow, swap or DAX entry.
*/
static inline struct folio *filemap_get_folio(struct address_space *mapping,
pgoff_t index)
@ -537,8 +538,8 @@ static inline struct folio *filemap_get_folio(struct address_space *mapping,
* present, it is returned locked with an increased refcount.
*
* Context: May sleep.
* Return: A folio or %NULL if there is no folio in the cache for this
* index. Will not return a shadow, swap or DAX entry.
* Return: A folio or ERR_PTR(-ENOENT) if there is no folio in the cache for
* this index. Will not return a shadow, swap or DAX entry.
*/
static inline struct folio *filemap_lock_folio(struct address_space *mapping,
pgoff_t index)
@ -555,8 +556,8 @@ static inline struct folio *filemap_lock_folio(struct address_space *mapping,
* a new folio is created. The folio is locked, marked as accessed, and
* returned.
*
* Return: A found or created folio. NULL if no folio is found and failed to
* create a folio.
* Return: A found or created folio. ERR_PTR(-ENOMEM) if no folio is found
* and failed to create a folio.
*/
static inline struct folio *filemap_grab_folio(struct address_space *mapping,
pgoff_t index)

14
mm/filemap.c
View file

@ -1907,7 +1907,7 @@ void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
*
* If there is a page cache page, it is returned with an increased refcount.
*
* Return: The found folio or %NULL otherwise.
* Return: The found folio or an ERR_PTR() otherwise.
*/
struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
int fgp_flags, gfp_t gfp)
@ -1925,7 +1925,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
if (fgp_flags & FGP_NOWAIT) {
if (!folio_trylock(folio)) {
folio_put(folio);
return NULL;
return ERR_PTR(-EAGAIN);
}
} else {
folio_lock(folio);
@ -1964,7 +1964,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
folio = filemap_alloc_folio(gfp, 0);
if (!folio)
return NULL;
return ERR_PTR(-ENOMEM);
if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))
fgp_flags |= FGP_LOCK;
@ -1989,6 +1989,8 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
folio_unlock(folio);
}
if (!folio)
return ERR_PTR(-ENOENT);
return folio;
}
EXPORT_SYMBOL(__filemap_get_folio);
@ -3258,7 +3260,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
* Do we have something in the page cache already?
*/
folio = filemap_get_folio(mapping, index);
if (likely(folio)) {
if (likely(!IS_ERR(folio))) {
/*
* We found the page, so try async readahead before waiting for
* the lock.
@ -3287,7 +3289,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
folio = __filemap_get_folio(mapping, index,
FGP_CREAT|FGP_FOR_MMAP,
vmf->gfp_mask);
if (!folio) {
if (IS_ERR(folio)) {
if (fpin)
goto out_retry;
filemap_invalidate_unlock_shared(mapping);
@ -3638,7 +3640,7 @@ static struct folio *do_read_cache_folio(struct address_space *mapping,
filler = mapping->a_ops->read_folio;
repeat:
folio = filemap_get_folio(mapping, index);
if (!folio) {
if (IS_ERR(folio)) {
folio = filemap_alloc_folio(gfp, 0);
if (!folio)
return ERR_PTR(-ENOMEM);

2
mm/folio-compat.c
View file

@ -97,7 +97,7 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
struct folio *folio;
folio = __filemap_get_folio(mapping, index, fgp_flags, gfp);
if (!folio)
if (IS_ERR(folio))
return NULL;
return folio_file_page(folio, index);
}

2
mm/huge_memory.c
View file

@ -3092,7 +3092,7 @@ static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
struct folio *folio = filemap_get_folio(mapping, index);
nr_pages = 1;
if (!folio)
if (IS_ERR(folio))
continue;
if (!folio_test_large(folio))

6
mm/hugetlb.c
View file

@ -5780,7 +5780,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
*/
new_folio = false;
folio = filemap_lock_folio(mapping, idx);
if (!folio) {
if (IS_ERR(folio)) {
size = i_size_read(mapping->host) >> huge_page_shift(h);
if (idx >= size)
goto out;
@ -6071,6 +6071,8 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
vma_end_reservation(h, vma, haddr);
pagecache_folio = filemap_lock_folio(mapping, idx);
if (IS_ERR(pagecache_folio))
pagecache_folio = NULL;
}
ptl = huge_pte_lock(h, mm, ptep);
@ -6182,7 +6184,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
if (is_continue) {
ret = -EFAULT;
folio = filemap_lock_folio(mapping, idx);
if (!folio)
if (IS_ERR(folio))
goto out;
folio_in_pagecache = true;
} else if (!*pagep) {

2
mm/memcontrol.c
View file

@ -5705,7 +5705,7 @@ static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
/* shmem/tmpfs may report page out on swap: account for that too. */
index = linear_page_index(vma, addr);
folio = filemap_get_incore_folio(vma->vm_file->f_mapping, index);
if (!folio)
if (IS_ERR(folio))
return NULL;
return folio_file_page(folio, index);
}

2
mm/mincore.c
View file

@ -61,7 +61,7 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t index)
* tmpfs's .fault). So swapped out tmpfs mappings are tested here.
*/
folio = filemap_get_incore_folio(mapping, index);
if (folio) {
if (!IS_ERR(folio)) {
present = folio_test_uptodate(folio);
folio_put(folio);
}

4
mm/shmem.c
View file

@ -605,7 +605,7 @@ static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
index = (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT;
folio = filemap_get_folio(inode->i_mapping, index);
if (!folio)
if (IS_ERR(folio))
goto drop;
/* No huge page at the end of the file: nothing to split */
@ -3214,7 +3214,7 @@ static const char *shmem_get_link(struct dentry *dentry,
if (!dentry) {
folio = filemap_get_folio(inode->i_mapping, 0);
if (!folio)
if (IS_ERR(folio))
return ERR_PTR(-ECHILD);
if (PageHWPoison(folio_page(folio, 0)) ||
!folio_test_uptodate(folio)) {

17
mm/swap_state.c
View file

@ -336,7 +336,7 @@ struct folio *swap_cache_get_folio(swp_entry_t entry,
struct folio *folio;
folio = filemap_get_folio(swap_address_space(entry), swp_offset(entry));
if (folio) {
if (!IS_ERR(folio)) {
bool vma_ra = swap_use_vma_readahead();
bool readahead;
@ -366,6 +366,8 @@ struct folio *swap_cache_get_folio(swp_entry_t entry,
if (!vma || !vma_ra)
atomic_inc(&swapin_readahead_hits);
}
} else {
folio = NULL;
}
return folio;
@ -388,23 +390,24 @@ struct folio *filemap_get_incore_folio(struct address_space *mapping,
struct swap_info_struct *si;
struct folio *folio = filemap_get_entry(mapping, index);
if (!folio)
return ERR_PTR(-ENOENT);
if (!xa_is_value(folio))
goto out;
return folio;
if (!shmem_mapping(mapping))
return NULL;
return ERR_PTR(-ENOENT);
swp = radix_to_swp_entry(folio);
/* There might be swapin error entries in shmem mapping. */
if (non_swap_entry(swp))
return NULL;
return ERR_PTR(-ENOENT);
/* Prevent swapoff from happening to us */
si = get_swap_device(swp);
if (!si)
return NULL;
return ERR_PTR(-ENOENT);
index = swp_offset(swp);
folio = filemap_get_folio(swap_address_space(swp), index);
put_swap_device(si);
out:
return folio;
}
@ -431,7 +434,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
folio = filemap_get_folio(swap_address_space(entry),
swp_offset(entry));
put_swap_device(si);
if (folio)
if (!IS_ERR(folio))
return folio_file_page(folio, swp_offset(entry));
/*

4
mm/swapfile.c
View file

@ -136,7 +136,7 @@ static int __try_to_reclaim_swap(struct swap_info_struct *si,
int ret = 0;
folio = filemap_get_folio(swap_address_space(entry), offset);
if (!folio)
if (IS_ERR(folio))
return 0;
/*
* When this function is called from scan_swap_map_slots() and it's
@ -2095,7 +2095,7 @@ static int try_to_unuse(unsigned int type)
entry = swp_entry(type, i);
folio = filemap_get_folio(swap_address_space(entry), i);
if (!folio)
if (IS_ERR(folio))
continue;
/*

15
mm/truncate.c
View file

@ -375,7 +375,7 @@ void truncate_inode_pages_range(struct address_space *mapping,
same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
folio = __filemap_get_folio(mapping, lstart >> PAGE_SHIFT, FGP_LOCK, 0);
if (folio) {
if (!IS_ERR(folio)) {
same_folio = lend < folio_pos(folio) + folio_size(folio);
if (!truncate_inode_partial_folio(folio, lstart, lend)) {
start = folio->index + folio_nr_pages(folio);
@ -387,14 +387,15 @@ void truncate_inode_pages_range(struct address_space *mapping,
folio = NULL;
}
if (!same_folio)
if (!same_folio) {
folio = __filemap_get_folio(mapping, lend >> PAGE_SHIFT,
FGP_LOCK, 0);
if (folio) {
if (!truncate_inode_partial_folio(folio, lstart, lend))
end = folio->index;
folio_unlock(folio);
folio_put(folio);
if (!IS_ERR(folio)) {
if (!truncate_inode_partial_folio(folio, lstart, lend))
end = folio->index;
folio_unlock(folio);
folio_put(folio);
}
}
index = start;