diff options
Diffstat (limited to 'mm/shmem.c')
| -rw-r--r-- | mm/shmem.c | 42 |
1 files changed, 37 insertions, 5 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 29d5a024df48..be890844fc92 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -254,7 +254,7 @@ static void shmem_inode_unacct_blocks(struct inode *inode, long pages) } static const struct super_operations shmem_ops; -const struct address_space_operations shmem_aops; +static const struct address_space_operations shmem_aops; static const struct file_operations shmem_file_operations; static const struct inode_operations shmem_inode_operations; static const struct inode_operations shmem_dir_inode_operations; @@ -263,6 +263,12 @@ static const struct vm_operations_struct shmem_vm_ops; static const struct vm_operations_struct shmem_anon_vm_ops; static struct file_system_type shmem_fs_type; +bool shmem_mapping(struct address_space *mapping) +{ + return mapping->a_ops == &shmem_aops; +} +EXPORT_SYMBOL_GPL(shmem_mapping); + bool vma_is_anon_shmem(struct vm_area_struct *vma) { return vma->vm_ops == &shmem_anon_vm_ops; @@ -1966,6 +1972,9 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index, int error; bool alloced; + if (WARN_ON_ONCE(!shmem_mapping(inode->i_mapping))) + return -EINVAL; + if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT)) return -EFBIG; repeat: @@ -2128,12 +2137,36 @@ unlock: return error; } +/** + * shmem_get_folio - find, and lock a shmem folio. + * @inode: inode to search + * @index: the page index. + * @foliop: pointer to the folio if found + * @sgp: SGP_* flags to control behavior + * + * Looks up the page cache entry at @inode & @index. If a folio is + * present, it is returned locked with an increased refcount. + * + * If the caller modifies data in the folio, it must call folio_mark_dirty() + * before unlocking the folio to ensure that the folio is not reclaimed. + * There is no need to reserve space before calling folio_mark_dirty(). + * + * When no folio is found, the behavior depends on @sgp: + * - for SGP_READ, *@foliop is %NULL and 0 is returned + * - for SGP_NOALLOC, *@foliop is %NULL and -ENOENT is returned + * - for all other flags a new folio is allocated, inserted into the + * page cache and returned locked in @foliop. + * + * Context: May sleep. + * 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) { return shmem_get_folio_gfp(inode, index, foliop, sgp, mapping_gfp_mask(inode->i_mapping), NULL, NULL); } +EXPORT_SYMBOL_GPL(shmem_get_folio); /* * This is like autoremove_wake_function, but it removes the wait queue @@ -3500,10 +3533,10 @@ static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir, inode->i_op = &shmem_short_symlink_operations; } else { inode_nohighmem(inode); + inode->i_mapping->a_ops = &shmem_aops; error = shmem_get_folio(inode, 0, &folio, SGP_WRITE); if (error) goto out_remove_offset; - inode->i_mapping->a_ops = &shmem_aops; inode->i_op = &shmem_symlink_inode_operations; memcpy(folio_address(folio), symname, len); folio_mark_uptodate(folio); @@ -4468,7 +4501,7 @@ static int shmem_error_remove_folio(struct address_space *mapping, return 0; } -const struct address_space_operations shmem_aops = { +static const struct address_space_operations shmem_aops = { .writepage = shmem_writepage, .dirty_folio = noop_dirty_folio, #ifdef CONFIG_TMPFS @@ -4480,7 +4513,6 @@ const struct address_space_operations shmem_aops = { #endif .error_remove_folio = shmem_error_remove_folio, }; -EXPORT_SYMBOL(shmem_aops); static const struct file_operations shmem_file_operations = { .mmap = shmem_mmap, @@ -4835,6 +4867,7 @@ struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned lon { return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE); } +EXPORT_SYMBOL_GPL(shmem_kernel_file_setup); /** * shmem_file_setup - get an unlinked file living in tmpfs @@ -4912,7 +4945,6 @@ struct folio *shmem_read_folio_gfp(struct address_space *mapping, struct folio *folio; int error; - BUG_ON(!shmem_mapping(mapping)); error = shmem_get_folio_gfp(inode, index, &folio, SGP_CACHE, gfp, NULL, NULL); if (error) |