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-rw-r--r--mm/shmem.c237
1 files changed, 108 insertions, 129 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 8f8534f35476..bf6e9c11d859 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1246,41 +1246,47 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t idx,
struct address_space *mapping = inode->i_mapping;
struct shmem_inode_info *info = SHMEM_I(inode);
struct shmem_sb_info *sbinfo;
- struct page *filepage;
- struct page *swappage;
+ struct page *page;
struct page *prealloc_page = NULL;
swp_entry_t *entry;
swp_entry_t swap;
int error;
+ int ret;
if (idx >= SHMEM_MAX_INDEX)
return -EFBIG;
repeat:
- filepage = find_lock_page(mapping, idx);
- if (filepage && PageUptodate(filepage))
- goto done;
- if (!filepage) {
+ page = find_lock_page(mapping, idx);
+ if (page) {
/*
- * Try to preload while we can wait, to not make a habit of
- * draining atomic reserves; but don't latch on to this cpu.
+ * Once we can get the page lock, it must be uptodate:
+ * if there were an error in reading back from swap,
+ * the page would not be inserted into the filecache.
*/
- error = radix_tree_preload(gfp & GFP_RECLAIM_MASK);
- if (error)
- goto failed;
- radix_tree_preload_end();
- if (sgp != SGP_READ && !prealloc_page) {
- prealloc_page = shmem_alloc_page(gfp, info, idx);
- if (prealloc_page) {
- SetPageSwapBacked(prealloc_page);
- if (mem_cgroup_cache_charge(prealloc_page,
- current->mm, GFP_KERNEL)) {
- page_cache_release(prealloc_page);
- prealloc_page = NULL;
- }
+ BUG_ON(!PageUptodate(page));
+ goto done;
+ }
+
+ /*
+ * Try to preload while we can wait, to not make a habit of
+ * draining atomic reserves; but don't latch on to this cpu.
+ */
+ error = radix_tree_preload(gfp & GFP_RECLAIM_MASK);
+ if (error)
+ goto out;
+ radix_tree_preload_end();
+
+ if (sgp != SGP_READ && !prealloc_page) {
+ prealloc_page = shmem_alloc_page(gfp, info, idx);
+ if (prealloc_page) {
+ SetPageSwapBacked(prealloc_page);
+ if (mem_cgroup_cache_charge(prealloc_page,
+ current->mm, GFP_KERNEL)) {
+ page_cache_release(prealloc_page);
+ prealloc_page = NULL;
}
}
}
- error = 0;
spin_lock(&info->lock);
shmem_recalc_inode(inode);
@@ -1288,21 +1294,21 @@ repeat:
if (IS_ERR(entry)) {
spin_unlock(&info->lock);
error = PTR_ERR(entry);
- goto failed;
+ goto out;
}
swap = *entry;
if (swap.val) {
/* Look it up and read it in.. */
- swappage = lookup_swap_cache(swap);
- if (!swappage) {
+ page = lookup_swap_cache(swap);
+ if (!page) {
shmem_swp_unmap(entry);
spin_unlock(&info->lock);
/* here we actually do the io */
if (fault_type)
*fault_type |= VM_FAULT_MAJOR;
- swappage = shmem_swapin(swap, gfp, info, idx);
- if (!swappage) {
+ page = shmem_swapin(swap, gfp, info, idx);
+ if (!page) {
spin_lock(&info->lock);
entry = shmem_swp_alloc(info, idx, sgp, gfp);
if (IS_ERR(entry))
@@ -1314,62 +1320,42 @@ repeat:
}
spin_unlock(&info->lock);
if (error)
- goto failed;
+ goto out;
goto repeat;
}
- wait_on_page_locked(swappage);
- page_cache_release(swappage);
+ wait_on_page_locked(page);
+ page_cache_release(page);
goto repeat;
}
/* We have to do this with page locked to prevent races */
- if (!trylock_page(swappage)) {
+ if (!trylock_page(page)) {
shmem_swp_unmap(entry);
spin_unlock(&info->lock);
- wait_on_page_locked(swappage);
- page_cache_release(swappage);
+ wait_on_page_locked(page);
+ page_cache_release(page);
goto repeat;
}
- if (PageWriteback(swappage)) {
+ if (PageWriteback(page)) {
shmem_swp_unmap(entry);
spin_unlock(&info->lock);
- wait_on_page_writeback(swappage);
- unlock_page(swappage);
- page_cache_release(swappage);
+ wait_on_page_writeback(page);
+ unlock_page(page);
+ page_cache_release(page);
goto repeat;
}
- if (!PageUptodate(swappage)) {
+ if (!PageUptodate(page)) {
shmem_swp_unmap(entry);
spin_unlock(&info->lock);
- unlock_page(swappage);
- page_cache_release(swappage);
+ unlock_page(page);
+ page_cache_release(page);
error = -EIO;
- goto failed;
+ goto out;
}
- if (filepage) {
- shmem_swp_set(info, entry, 0);
- shmem_swp_unmap(entry);
- delete_from_swap_cache(swappage);
- spin_unlock(&info->lock);
- copy_highpage(filepage, swappage);
- unlock_page(swappage);
- page_cache_release(swappage);
- flush_dcache_page(filepage);
- SetPageUptodate(filepage);
- set_page_dirty(filepage);
- swap_free(swap);
- } else if (!(error = add_to_page_cache_locked(swappage, mapping,
- idx, GFP_NOWAIT))) {
- info->flags |= SHMEM_PAGEIN;
- shmem_swp_set(info, entry, 0);
- shmem_swp_unmap(entry);
- delete_from_swap_cache(swappage);
- spin_unlock(&info->lock);
- filepage = swappage;
- set_page_dirty(filepage);
- swap_free(swap);
- } else {
+ error = add_to_page_cache_locked(page, mapping,
+ idx, GFP_NOWAIT);
+ if (error) {
shmem_swp_unmap(entry);
spin_unlock(&info->lock);
if (error == -ENOMEM) {
@@ -1378,28 +1364,33 @@ repeat:
* call memcg's OOM if needed.
*/
error = mem_cgroup_shmem_charge_fallback(
- swappage,
- current->mm,
- gfp);
+ page, current->mm, gfp);
if (error) {
- unlock_page(swappage);
- page_cache_release(swappage);
- goto failed;
+ unlock_page(page);
+ page_cache_release(page);
+ goto out;
}
}
- unlock_page(swappage);
- page_cache_release(swappage);
+ unlock_page(page);
+ page_cache_release(page);
goto repeat;
}
- } else if (sgp == SGP_READ && !filepage) {
+
+ info->flags |= SHMEM_PAGEIN;
+ shmem_swp_set(info, entry, 0);
shmem_swp_unmap(entry);
- filepage = find_get_page(mapping, idx);
- if (filepage &&
- (!PageUptodate(filepage) || !trylock_page(filepage))) {
+ delete_from_swap_cache(page);
+ spin_unlock(&info->lock);
+ set_page_dirty(page);
+ swap_free(swap);
+
+ } else if (sgp == SGP_READ) {
+ shmem_swp_unmap(entry);
+ page = find_get_page(mapping, idx);
+ if (page && !trylock_page(page)) {
spin_unlock(&info->lock);
- wait_on_page_locked(filepage);
- page_cache_release(filepage);
- filepage = NULL;
+ wait_on_page_locked(page);
+ page_cache_release(page);
goto repeat;
}
spin_unlock(&info->lock);
@@ -1417,56 +1408,52 @@ repeat:
} else if (shmem_acct_block(info->flags))
goto nospace;
- if (!filepage) {
- int ret;
+ page = prealloc_page;
+ prealloc_page = NULL;
- filepage = prealloc_page;
- prealloc_page = NULL;
-
- entry = shmem_swp_alloc(info, idx, sgp, gfp);
- if (IS_ERR(entry))
- error = PTR_ERR(entry);
- else {
- swap = *entry;
- shmem_swp_unmap(entry);
- }
- ret = error || swap.val;
- if (ret)
- mem_cgroup_uncharge_cache_page(filepage);
- else
- ret = add_to_page_cache_lru(filepage, mapping,
+ entry = shmem_swp_alloc(info, idx, sgp, gfp);
+ if (IS_ERR(entry))
+ error = PTR_ERR(entry);
+ else {
+ swap = *entry;
+ shmem_swp_unmap(entry);
+ }
+ ret = error || swap.val;
+ if (ret)
+ mem_cgroup_uncharge_cache_page(page);
+ else
+ ret = add_to_page_cache_lru(page, mapping,
idx, GFP_NOWAIT);
- /*
- * At add_to_page_cache_lru() failure, uncharge will
- * be done automatically.
- */
- if (ret) {
- shmem_unacct_blocks(info->flags, 1);
- shmem_free_blocks(inode, 1);
- spin_unlock(&info->lock);
- page_cache_release(filepage);
- filepage = NULL;
- if (error)
- goto failed;
- goto repeat;
- }
- info->flags |= SHMEM_PAGEIN;
+ /*
+ * At add_to_page_cache_lru() failure,
+ * uncharge will be done automatically.
+ */
+ if (ret) {
+ shmem_unacct_blocks(info->flags, 1);
+ shmem_free_blocks(inode, 1);
+ spin_unlock(&info->lock);
+ page_cache_release(page);
+ if (error)
+ goto out;
+ goto repeat;
}
+ info->flags |= SHMEM_PAGEIN;
info->alloced++;
spin_unlock(&info->lock);
- clear_highpage(filepage);
- flush_dcache_page(filepage);
- SetPageUptodate(filepage);
+ clear_highpage(page);
+ flush_dcache_page(page);
+ SetPageUptodate(page);
if (sgp == SGP_DIRTY)
- set_page_dirty(filepage);
+ set_page_dirty(page);
+
} else {
spin_unlock(&info->lock);
error = -ENOMEM;
goto out;
}
done:
- *pagep = filepage;
+ *pagep = page;
error = 0;
out:
if (prealloc_page) {
@@ -1482,21 +1469,13 @@ nospace:
* but must also avoid reporting a spurious ENOSPC while working on a
* full tmpfs.
*/
- if (!filepage) {
- struct page *page = find_get_page(mapping, idx);
- if (page) {
- spin_unlock(&info->lock);
- page_cache_release(page);
- goto repeat;
- }
- }
+ page = find_get_page(mapping, idx);
spin_unlock(&info->lock);
- error = -ENOSPC;
-failed:
- if (filepage) {
- unlock_page(filepage);
- page_cache_release(filepage);
+ if (page) {
+ page_cache_release(page);
+ goto repeat;
}
+ error = -ENOSPC;
goto out;
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-16 03:25:59 +0000