The patch titled
fs: fix cont vs deadlock patches
has been added to the -mm tree. Its filename is
fs-fix-cont-vs-deadlock-patches.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: fs: fix cont vs deadlock patches
From: Nick Piggin <npiggin@xxxxxxx>
Stop overloading zero length prepare/commit_write to request a
file extend operation by the "cont" buffer code. Instead, have
generic_cont_expand perform a zeroing operation on the last
page, and cont_prepare_write naturally zeroes any previous
pages required.
Signed-off-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Reiserfs was trying to "extend" a file to something smaller than
it already is with generic_cont_expand. This broke the above fix.
Open code the prepare/ commit pair instead... maybe the code would
be cleaner if reiserfs just did the operation explicitly (call
get_block or whatever helper is used to unpack the tail)?
Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/buffer.c | 59 +++++++++++++---------------------
fs/fat/file.c | 2 -
fs/reiserfs/file.c | 37 +++++++++++++++++++--
include/linux/buffer_head.h | 1
4 files changed, 57 insertions(+), 42 deletions(-)
diff -puN fs/buffer.c~fs-fix-cont-vs-deadlock-patches fs/buffer.c
--- a/fs/buffer.c~fs-fix-cont-vs-deadlock-patches
+++ a/fs/buffer.c
@@ -2004,18 +2004,24 @@ int block_read_full_page(struct page *pa
return 0;
}
-/* utility function for filesystems that need to do work on expanding
+/*
+ * utility function for filesystems that need to do work on expanding
* truncates. Uses prepare/commit_write to allow the filesystem to
* deal with the hole.
*/
-static int __generic_cont_expand(struct inode *inode, loff_t size,
- pgoff_t index, unsigned int offset)
+int generic_cont_expand(struct inode *inode, loff_t size)
{
struct address_space *mapping = inode->i_mapping;
+ loff_t pos = inode->i_size;
struct page *page;
unsigned long limit;
+ pgoff_t index;
+ unsigned int from, to;
+ void *kaddr;
int err;
+ WARN_ON(pos >= size);
+
err = -EFBIG;
limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
if (limit != RLIM_INFINITY && size > (loff_t)limit) {
@@ -2025,11 +2031,18 @@ static int __generic_cont_expand(struct
if (size > inode->i_sb->s_maxbytes)
goto out;
+ index = (size - 1) >> PAGE_CACHE_SHIFT;
+ to = size - ((loff_t)index << PAGE_CACHE_SHIFT);
+ if (index != (pos >> PAGE_CACHE_SHIFT))
+ from = 0;
+ else
+ from = pos & (PAGE_CACHE_SIZE - 1);
+
err = -ENOMEM;
page = grab_cache_page(mapping, index);
if (!page)
goto out;
- err = mapping->a_ops->prepare_write(NULL, page, offset, offset);
+ err = mapping->a_ops->prepare_write(NULL, page, from, to);
if (err) {
/*
* ->prepare_write() may have instantiated a few blocks
@@ -2041,7 +2054,12 @@ static int __generic_cont_expand(struct
goto out;
}
- err = mapping->a_ops->commit_write(NULL, page, offset, offset);
+ kaddr = kmap_atomic(page, KM_USER0);
+ memset(kaddr + from, 0, to - from);
+ flush_dcache_page(page);
+ kunmap_atomic(kaddr, KM_USER0);
+
+ err = mapping->a_ops->commit_write(NULL, page, from, to);
unlock_page(page);
page_cache_release(page);
@@ -2051,36 +2069,6 @@ out:
return err;
}
-int generic_cont_expand(struct inode *inode, loff_t size)
-{
- pgoff_t index;
- unsigned int offset;
-
- offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */
-
- /* ugh. in prepare/commit_write, if from==to==start of block, we
- ** skip the prepare. make sure we never send an offset for the start
- ** of a block
- */
- if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
- /* caller must handle this extra byte. */
- offset++;
- }
- index = size >> PAGE_CACHE_SHIFT;
-
- return __generic_cont_expand(inode, size, index, offset);
-}
-
-int generic_cont_expand_simple(struct inode *inode, loff_t size)
-{
- loff_t pos = size - 1;
- pgoff_t index = pos >> PAGE_CACHE_SHIFT;
- unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1;
-
- /* prepare/commit_write can handle even if from==to==start of block. */
- return __generic_cont_expand(inode, size, index, offset);
-}
-
/*
* For moronic filesystems that do not allow holes in file.
* We may have to extend the file.
@@ -3014,7 +3002,6 @@ EXPORT_SYMBOL(fsync_bdev);
EXPORT_SYMBOL(generic_block_bmap);
EXPORT_SYMBOL(generic_commit_write);
EXPORT_SYMBOL(generic_cont_expand);
-EXPORT_SYMBOL(generic_cont_expand_simple);
EXPORT_SYMBOL(init_buffer);
EXPORT_SYMBOL(invalidate_bdev);
EXPORT_SYMBOL(ll_rw_block);
diff -puN fs/fat/file.c~fs-fix-cont-vs-deadlock-patches fs/fat/file.c
--- a/fs/fat/file.c~fs-fix-cont-vs-deadlock-patches
+++ a/fs/fat/file.c
@@ -143,7 +143,7 @@ static int fat_cont_expand(struct inode
loff_t start = inode->i_size, count = size - inode->i_size;
int err;
- err = generic_cont_expand_simple(inode, size);
+ err = generic_cont_expand(inode, size);
if (err)
goto out;
diff -puN fs/fat/inode.c~fs-fix-cont-vs-deadlock-patches fs/fat/inode.c
diff -puN fs/reiserfs/file.c~fs-fix-cont-vs-deadlock-patches fs/reiserfs/file.c
--- a/fs/reiserfs/file.c~fs-fix-cont-vs-deadlock-patches
+++ a/fs/reiserfs/file.c
@@ -892,6 +892,37 @@ static int reiserfs_submit_file_region_f
return retval;
}
+/* To not overcomplicate matters, we just call prepare/commit_wrie
+ which will in turn call other stuff and finally will boil down to
+ reiserfs_get_block() that would do necessary conversion. */
+static int reiserfs_convert_tail(struct inode *inode, loff_t offset)
+{
+ struct address_space *mapping = inode->i_mapping;
+ pgoff_t index;
+ struct page *page;
+ int err = -ENOMEM;
+
+ index = offset >> PAGE_CACHE_SHIFT;
+ page = grab_cache_page(mapping, index);
+ if (!page)
+ goto out;
+
+ offset = offset & ~PAGE_CACHE_MASK;
+ WARN_ON(!offset); /* shouldn't pass zero length to prepare/commit */
+
+ err = mapping->a_ops->prepare_write(NULL, page, 0, offset);
+ if (err)
+ goto out_unlock;
+
+ err = mapping->a_ops->commit_write(NULL, page, 0, offset);
+
+out_unlock:
+ unlock_page(page);
+ page_cache_release(page);
+out:
+ return err;
+}
+
/* Look if passed writing region is going to touch file's tail
(if it is present). And if it is, convert the tail to unformatted node */
static int reiserfs_check_for_tail_and_convert(struct inode *inode, /* inode to deal with */
@@ -930,14 +961,12 @@ static int reiserfs_check_for_tail_and_c
if (is_direct_le_ih(ih)) {
/* Ok, closest item is file tail (tails are stored in "direct"
* items), so we need to unpack it. */
- /* To not overcomplicate matters, we just call generic_cont_expand
- which will in turn call other stuff and finally will boil down to
- reiserfs_get_block() that would do necessary conversion. */
cont_expand_offset =
le_key_k_offset(get_inode_item_key_version(inode),
&(ih->ih_key));
pathrelse(&path);
- res = generic_cont_expand(inode, cont_expand_offset);
+
+ res = reiserfs_convert_tail(inode, cont_expand_offset);
} else
pathrelse(&path);
diff -puN include/linux/buffer_head.h~fs-fix-cont-vs-deadlock-patches include/linux/buffer_head.h
--- a/include/linux/buffer_head.h~fs-fix-cont-vs-deadlock-patches
+++ a/include/linux/buffer_head.h
@@ -203,7 +203,6 @@ int block_prepare_write(struct page*, un
int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
loff_t *);
int generic_cont_expand(struct inode *inode, loff_t size);
-int generic_cont_expand_simple(struct inode *inode, loff_t size);
int block_commit_write(struct page *page, unsigned from, unsigned to);
void block_sync_page(struct page *);
sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
_
Patches currently in -mm which might be from npiggin@xxxxxxx are
mm-only-mm-debug-write-deadlocks.patch
mm-fix-pagecache-write-deadlocks.patch
mm-fix-pagecache-write-deadlocks-comment.patch
mm-fix-pagecache-write-deadlocks-mm-pagecache-write-deadlocks-efault-fix.patch
mm-fix-pagecache-write-deadlocks-zerolength-fix.patch
mm-fix-pagecache-write-deadlocks-stale-holes-fix.patch
fs-prepare_write-fixes.patch
fs-prepare_write-fixes-fuse-fix.patch
fs-prepare_write-fixes-jffs-fix.patch
fs-prepare_write-fixes-fat-fix.patch
fs-fix-cont-vs-deadlock-patches.patch
oom-dont-kill-unkillable-children-or-siblings.patch
oom-cleanup-messages.patch
oom-less-memdie.patch
mm-incorrect-vm_fault_oom-returns-from-drivers.patch
mm-add-arch_alloc_page.patch
mm-arch-do_page_fault-vs-in_atomic.patch
mm-pagefault_disableenable.patch
mm-kummap_atomic-vs-in_atomic.patch
radix-tree-rcu-lockless-readside.patch
-
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