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-rw-r--r--mm/shmem.c105
1 files changed, 72 insertions, 33 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 9b90d89e54ce..793dcd1bac8b 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -89,7 +89,8 @@ enum sgp_type {
SGP_READ, /* don't exceed i_size, don't allocate page */
SGP_CACHE, /* don't exceed i_size, may allocate page */
SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
- SGP_WRITE, /* may exceed i_size, may allocate page */
+ SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */
+ SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */
};
#ifdef CONFIG_TMPFS
@@ -427,8 +428,10 @@ void shmem_unlock_mapping(struct address_space *mapping)
/*
* Remove range of pages and swap entries from radix tree, and free them.
+ * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
*/
-void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
+static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
+ bool unfalloc)
{
struct address_space *mapping = inode->i_mapping;
struct shmem_inode_info *info = SHMEM_I(inode);
@@ -462,6 +465,8 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
break;
if (radix_tree_exceptional_entry(page)) {
+ if (unfalloc)
+ continue;
nr_swaps_freed += !shmem_free_swap(mapping,
index, page);
continue;
@@ -469,9 +474,11 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
if (!trylock_page(page))
continue;
- if (page->mapping == mapping) {
- VM_BUG_ON(PageWriteback(page));
- truncate_inode_page(mapping, page);
+ if (!unfalloc || !PageUptodate(page)) {
+ if (page->mapping == mapping) {
+ VM_BUG_ON(PageWriteback(page));
+ truncate_inode_page(mapping, page);
+ }
}
unlock_page(page);
}
@@ -517,12 +524,12 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
min(end - index, (pgoff_t)PAGEVEC_SIZE),
pvec.pages, indices);
if (!pvec.nr) {
- if (index == start)
+ if (index == start || unfalloc)
break;
index = start;
continue;
}
- if (index == start && indices[0] >= end) {
+ if ((index == start || unfalloc) && indices[0] >= end) {
shmem_deswap_pagevec(&pvec);
pagevec_release(&pvec);
break;
@@ -536,15 +543,19 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
break;
if (radix_tree_exceptional_entry(page)) {
+ if (unfalloc)
+ continue;
nr_swaps_freed += !shmem_free_swap(mapping,
index, page);
continue;
}
lock_page(page);
- if (page->mapping == mapping) {
- VM_BUG_ON(PageWriteback(page));
- truncate_inode_page(mapping, page);
+ if (!unfalloc || !PageUptodate(page)) {
+ if (page->mapping == mapping) {
+ VM_BUG_ON(PageWriteback(page));
+ truncate_inode_page(mapping, page);
+ }
}
unlock_page(page);
}
@@ -558,7 +569,11 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
info->swapped -= nr_swaps_freed;
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
+}
+void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
+{
+ shmem_undo_range(inode, lstart, lend, false);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
}
EXPORT_SYMBOL_GPL(shmem_truncate_range);
@@ -771,6 +786,18 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
goto redirty;
}
+
+ /*
+ * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
+ * value into swapfile.c, the only way we can correctly account for a
+ * fallocated page arriving here is now to initialize it and write it.
+ */
+ if (!PageUptodate(page)) {
+ clear_highpage(page);
+ flush_dcache_page(page);
+ SetPageUptodate(page);
+ }
+
swap = get_swap_page();
if (!swap.val)
goto redirty;
@@ -994,6 +1021,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
swp_entry_t swap;
int error;
int once = 0;
+ int alloced = 0;
if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT))
return -EFBIG;
@@ -1005,19 +1033,21 @@ repeat:
page = NULL;
}
- if (sgp != SGP_WRITE &&
+ if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
error = -EINVAL;
goto failed;
}
+ /* fallocated page? */
+ if (page && !PageUptodate(page)) {
+ if (sgp != SGP_READ)
+ goto clear;
+ unlock_page(page);
+ page_cache_release(page);
+ page = NULL;
+ }
if (page || (sgp == SGP_READ && !swap.val)) {
- /*
- * 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.
- */
- BUG_ON(page && !PageUptodate(page));
*pagep = page;
return 0;
}
@@ -1114,9 +1144,18 @@ repeat:
inode->i_blocks += BLOCKS_PER_PAGE;
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
+ alloced = true;
/*
- * Let SGP_WRITE caller clear ends if write does not fill page
+ * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
+ */
+ if (sgp == SGP_FALLOC)
+ sgp = SGP_WRITE;
+clear:
+ /*
+ * Let SGP_WRITE caller clear ends if write does not fill page;
+ * but SGP_FALLOC on a page fallocated earlier must initialize
+ * it now, lest undo on failure cancel our earlier guarantee.
*/
if (sgp != SGP_WRITE) {
clear_highpage(page);
@@ -1128,10 +1167,13 @@ repeat:
}
/* Perhaps the file has been truncated since we checked */
- if (sgp != SGP_WRITE &&
+ if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
error = -EINVAL;
- goto trunc;
+ if (alloced)
+ goto trunc;
+ else
+ goto failed;
}
*pagep = page;
return 0;
@@ -1140,6 +1182,7 @@ repeat:
* Error recovery.
*/
trunc:
+ info = SHMEM_I(inode);
ClearPageDirty(page);
delete_from_page_cache(page);
spin_lock(&info->lock);
@@ -1147,6 +1190,7 @@ trunc:
inode->i_blocks -= BLOCKS_PER_PAGE;
spin_unlock(&info->lock);
decused:
+ sbinfo = SHMEM_SB(inode->i_sb);
if (sbinfo->max_blocks)
percpu_counter_add(&sbinfo->used_blocks, -1);
unacct:
@@ -1645,25 +1689,20 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
if (signal_pending(current))
error = -EINTR;
else
- error = shmem_getpage(inode, index, &page, SGP_WRITE,
+ error = shmem_getpage(inode, index, &page, SGP_FALLOC,
NULL);
if (error) {
- /*
- * We really ought to free what we allocated so far,
- * but it would be wrong to free pages allocated
- * earlier, or already now in use: i_mutex does not
- * exclude all cases. We do not know what to free.
- */
+ /* Remove the !PageUptodate pages we added */
+ shmem_undo_range(inode,
+ (loff_t)start << PAGE_CACHE_SHIFT,
+ (loff_t)index << PAGE_CACHE_SHIFT, true);
goto ctime;
}
- if (!PageUptodate(page)) {
- clear_highpage(page);
- flush_dcache_page(page);
- SetPageUptodate(page);
- }
/*
- * set_page_dirty so that memory pressure will swap rather
+ * If !PageUptodate, leave it that way so that freeable pages
+ * can be recognized if we need to rollback on error later.
+ * But set_page_dirty so that memory pressure will swap rather
* than free the pages we are allocating (and SGP_CACHE pages
* might still be clean: we now need to mark those dirty too).
*/
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-20 16:39:42 +0000