diff options
| author | Kairui Song <kasong@tencent.com> | 2022-12-20 02:58:40 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-01-18 17:12:45 -0800 |
| commit | cbc2bd98db85504074c1b94175e5e136e457dc0b (patch) | |
| tree | 67775d3bb34faee300c78a1e88c82e366956f2f3 /mm/shmem.c | |
| parent | 16ba391e9c6bc26e6f0c950f2117f57b8e542d71 (diff) | |
swap: avoid holding swap reference in swap_cache_get_folio
All its callers either already hold a reference to, or lock the swap
device while calling this function. There is only one exception in
shmem_swapin_folio, just make this caller also hold a reference of the
swap device, so this helper can be simplified and saves a few cycles.
This also provides finer control of error handling in shmem_swapin_folio,
on race (with swap off), it can just try again. For invalid swap entry,
it can fail with a proper error code.
Link: https://lkml.kernel.org/r/20221219185840.25441-5-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/shmem.c')
| -rw-r--r-- | mm/shmem.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index d3f0c94f6836..bc5c156ef470 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1739,6 +1739,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index, struct address_space *mapping = inode->i_mapping; struct shmem_inode_info *info = SHMEM_I(inode); struct mm_struct *charge_mm = vma ? vma->vm_mm : NULL; + struct swap_info_struct *si; struct folio *folio = NULL; swp_entry_t swap; int error; @@ -1750,6 +1751,14 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index, if (is_swapin_error_entry(swap)) return -EIO; + si = get_swap_device(swap); + if (!si) { + if (!shmem_confirm_swap(mapping, index, swap)) + return -EEXIST; + else + return -EINVAL; + } + /* Look it up and read it in.. */ folio = swap_cache_get_folio(swap, NULL, 0); if (!folio) { @@ -1810,6 +1819,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index, delete_from_swap_cache(folio); folio_mark_dirty(folio); swap_free(swap); + put_swap_device(si); *foliop = folio; return 0; @@ -1823,6 +1833,7 @@ unlock: folio_unlock(folio); folio_put(folio); } + put_swap_device(si); return error; } |