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authorLukas Czerner <lczerner@redhat.com>2015-04-03 00:09:13 -0400
committerTheodore Ts'o <tytso@mit.edu>2015-04-03 00:09:13 -0400
commit0f2af21aae11972fa924374ddcf52e88347cf5a8 (patch)
tree753b0c67fecebe1cc2bf15ca775b9ea13312b85c /fs/ext4
parent5a4f3145aa685ddc2caf424763d42d3eaaebbc6f (diff)
downloadop-kernel-dev-0f2af21aae11972fa924374ddcf52e88347cf5a8.zip
op-kernel-dev-0f2af21aae11972fa924374ddcf52e88347cf5a8.tar.gz
ext4: allocate entire range in zero range
Currently there is a bug in zero range code which causes zero range calls to only allocate block aligned portion of the range, while ignoring the rest in some cases. In some cases, namely if the end of the range is past i_size, we do attempt to preallocate the last nonaligned block. However this might cause kernel to BUG() in some carefully designed zero range requests on setups where page size > block size. Fix this problem by first preallocating the entire range, including the nonaligned edges and converting the written extents to unwritten in the next step. This approach will also give us the advantage of having the range to be as linearly contiguous as possible. Signed-off-by: Lukas Czerner <lczerner@redhat.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/extents.c31
1 files changed, 19 insertions, 12 deletions
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 2e6af88..3cc17aa 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4797,12 +4797,6 @@ static long ext4_zero_range(struct file *file, loff_t offset,
else
max_blocks -= lblk;
- flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT |
- EXT4_GET_BLOCKS_CONVERT_UNWRITTEN |
- EXT4_EX_NOCACHE;
- if (mode & FALLOC_FL_KEEP_SIZE)
- flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
-
mutex_lock(&inode->i_mutex);
/*
@@ -4819,15 +4813,28 @@ static long ext4_zero_range(struct file *file, loff_t offset,
ret = inode_newsize_ok(inode, new_size);
if (ret)
goto out_mutex;
- /*
- * If we have a partial block after EOF we have to allocate
- * the entire block.
- */
- if (partial_end)
- max_blocks += 1;
}
+ flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT;
+ if (mode & FALLOC_FL_KEEP_SIZE)
+ flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
+
+ /* Preallocate the range including the unaligned edges */
+ if (partial_begin || partial_end) {
+ ret = ext4_alloc_file_blocks(file,
+ round_down(offset, 1 << blkbits) >> blkbits,
+ (round_up((offset + len), 1 << blkbits) -
+ round_down(offset, 1 << blkbits)) >> blkbits,
+ new_size, flags, mode);
+ if (ret)
+ goto out_mutex;
+
+ }
+
+ /* Zero range excluding the unaligned edges */
if (max_blocks > 0) {
+ flags |= (EXT4_GET_BLOCKS_CONVERT_UNWRITTEN |
+ EXT4_EX_NOCACHE);
/* Now release the pages and zero block aligned part of pages*/
truncate_pagecache_range(inode, start, end - 1);
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