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author | Theodore Ts'o <tytso@mit.edu> | 2013-04-03 12:45:17 -0400 |
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committer | Theodore Ts'o <tytso@mit.edu> | 2013-04-03 12:45:17 -0400 |
commit | 26a4c0c6ccecf6814cf44f951c97222bd795bc1a (patch) | |
tree | 9b3a2fa02c61464ead1456499cad46e41644878b /fs/ext4/indirect.c | |
parent | 781f143ea0fd7981ebe2e8cd96114997c8cf6c07 (diff) | |
download | linux-stable-26a4c0c6ccecf6814cf44f951c97222bd795bc1a.tar.gz linux-stable-26a4c0c6ccecf6814cf44f951c97222bd795bc1a.tar.bz2 linux-stable-26a4c0c6ccecf6814cf44f951c97222bd795bc1a.zip |
ext4: refactor punch hole code
Move common code in ext4_ind_punch_hole() and ext4_ext_punch_hole()
into ext4_punch_hole(). This saves over 150 lines of code.
This also fixes a potential bug when the punch_hole() code is racing
against indirect-to-extents or extents-to-indirect migation. We are
currently using i_mutex to protect against changes to the inode flag;
specifically, the append-only, immutable, and extents inode flags. So
we need to take i_mutex before deciding whether to use the
extents-specific or indirect-specific punch_hole code.
Also, there was a missing call to ext4_inode_block_unlocked_dio() in
the indirect punch codepath. This was added in commit 02d262dffcf4c
to block DIO readers racing against the punch operation in the
codepath for extent-mapped inodes, but it was missing for
indirect-block mapped inodes. One of the advantages of refactoring
the code is that it makes such oversights much less likely.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/indirect.c')
-rw-r--r-- | fs/ext4/indirect.c | 158 |
1 files changed, 2 insertions, 156 deletions
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c index c0f9e4699f0b..d8846779f4ea 100644 --- a/fs/ext4/indirect.c +++ b/fs/ext4/indirect.c @@ -1434,8 +1434,8 @@ err: return ret; } -static int ext4_free_hole_blocks(handle_t *handle, struct inode *inode, - ext4_lblk_t first, ext4_lblk_t stop) +int ext4_free_hole_blocks(handle_t *handle, struct inode *inode, + ext4_lblk_t first, ext4_lblk_t stop) { int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb); int level, ret = 0; @@ -1469,157 +1469,3 @@ err: return ret; } -int ext4_ind_punch_hole(struct file *file, loff_t offset, loff_t length) -{ - struct inode *inode = file_inode(file); - struct super_block *sb = inode->i_sb; - ext4_lblk_t first_block, stop_block; - struct address_space *mapping = inode->i_mapping; - handle_t *handle = NULL; - loff_t first_page, last_page, page_len; - loff_t first_page_offset, last_page_offset; - int err = 0; - - /* - * Write out all dirty pages to avoid race conditions - * Then release them. - */ - if (mapping->nrpages && mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { - err = filemap_write_and_wait_range(mapping, - offset, offset + length - 1); - if (err) - return err; - } - - mutex_lock(&inode->i_mutex); - /* It's not possible punch hole on append only file */ - if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) { - err = -EPERM; - goto out_mutex; - } - if (IS_SWAPFILE(inode)) { - err = -ETXTBSY; - goto out_mutex; - } - - /* No need to punch hole beyond i_size */ - if (offset >= inode->i_size) - goto out_mutex; - - /* - * If the hole extents beyond i_size, set the hole - * to end after the page that contains i_size - */ - if (offset + length > inode->i_size) { - length = inode->i_size + - PAGE_CACHE_SIZE - (inode->i_size & (PAGE_CACHE_SIZE - 1)) - - offset; - } - - first_page = (offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; - last_page = (offset + length) >> PAGE_CACHE_SHIFT; - - first_page_offset = first_page << PAGE_CACHE_SHIFT; - last_page_offset = last_page << PAGE_CACHE_SHIFT; - - /* Now release the pages */ - if (last_page_offset > first_page_offset) { - truncate_pagecache_range(inode, first_page_offset, - last_page_offset - 1); - } - - /* Wait all existing dio works, newcomers will block on i_mutex */ - inode_dio_wait(inode); - - handle = start_transaction(inode); - if (IS_ERR(handle)) - goto out_mutex; - - /* - * Now we need to zero out the non-page-aligned data in the - * pages at the start and tail of the hole, and unmap the buffer - * heads for the block aligned regions of the page that were - * completely zerod. - */ - if (first_page > last_page) { - /* - * If the file space being truncated is contained within a page - * just zero out and unmap the middle of that page - */ - err = ext4_discard_partial_page_buffers(handle, - mapping, offset, length, 0); - if (err) - goto out; - } else { - /* - * Zero out and unmap the paritial page that contains - * the start of the hole - */ - page_len = first_page_offset - offset; - if (page_len > 0) { - err = ext4_discard_partial_page_buffers(handle, mapping, - offset, page_len, 0); - if (err) - goto out; - } - - /* - * Zero out and unmap the partial page that contains - * the end of the hole - */ - page_len = offset + length - last_page_offset; - if (page_len > 0) { - err = ext4_discard_partial_page_buffers(handle, mapping, - last_page_offset, page_len, 0); - if (err) - goto out; - } - } - - /* - * If i_size contained in the last page, we need to - * unmap and zero the paritial page after i_size - */ - if (inode->i_size >> PAGE_CACHE_SHIFT == last_page && - inode->i_size % PAGE_CACHE_SIZE != 0) { - page_len = PAGE_CACHE_SIZE - - (inode->i_size & (PAGE_CACHE_SIZE - 1)); - if (page_len > 0) { - err = ext4_discard_partial_page_buffers(handle, - mapping, inode->i_size, page_len, 0); - if (err) - goto out; - } - } - - first_block = (offset + sb->s_blocksize - 1) >> - EXT4_BLOCK_SIZE_BITS(sb); - stop_block = (offset + length) >> EXT4_BLOCK_SIZE_BITS(sb); - - if (first_block >= stop_block) - goto out; - - down_write(&EXT4_I(inode)->i_data_sem); - ext4_discard_preallocations(inode); - - err = ext4_es_remove_extent(inode, first_block, - stop_block - first_block); - err = ext4_free_hole_blocks(handle, inode, first_block, stop_block); - - ext4_discard_preallocations(inode); - - if (IS_SYNC(inode)) - ext4_handle_sync(handle); - - up_write(&EXT4_I(inode)->i_data_sem); - -out: - inode->i_mtime = inode->i_ctime = ext4_current_time(inode); - ext4_mark_inode_dirty(handle, inode); - ext4_journal_stop(handle); - -out_mutex: - mutex_unlock(&inode->i_mutex); - - return err; -} |