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ext4: factor out ext4_truncate_[up|down]()
Refactor ext4_setattr() by introducing two helper functions, ext4_truncate_up() and ext4_truncate_down(), to handle size changes. The current ATTR_SIZE processing consolidates checks for both shrinking and non-shrinking cases, leading to cluttered code. Separating the truncation paths improves readability. Signed-off-by: Zhang Yi <yi.zhang@huawei.com> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Reviewed-by: Jan Kara <jack@suse.cz> Tested-by: syzbot@syzkaller.appspotmail.com Link: https://patch.msgid.link/20261009103033.2920530-3-yi.zhang@huaweicloud.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Zhang Yi
Theodore Ts'o
parent
e9941268ba
commit
bbe1fc8a29
199
fs/ext4/inode.c
199
fs/ext4/inode.c
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@ -5982,6 +5982,112 @@ static void ext4_wait_for_tail_page_commit(struct inode *inode)
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}
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}
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/*
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* Set i_size and i_disksize to 'newsize'.
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*
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* Both i_rwsem and i_data_sem are required here to avoid races between
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* generic append writeback and concurrent truncate that also modify
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* i_size and i_disksize.
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*/
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static inline void ext4_set_inode_size(struct inode *inode, loff_t newsize)
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{
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WARN_ON_ONCE(S_ISREG(inode->i_mode) && !inode_is_locked(inode));
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down_write(&EXT4_I(inode)->i_data_sem);
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i_size_write(inode, newsize);
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EXT4_I(inode)->i_disksize = newsize;
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up_write(&EXT4_I(inode)->i_data_sem);
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}
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static int ext4_truncate_up(struct inode *inode, loff_t oldsize, loff_t newsize)
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{
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ext4_lblk_t old_lblk, new_lblk;
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handle_t *handle;
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int ret;
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if (!IS_ALIGNED(oldsize | newsize, i_blocksize(inode))) {
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ret = ext4_inode_attach_jinode(inode);
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if (ret)
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return ret;
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}
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inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
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if (!IS_ALIGNED(oldsize, i_blocksize(inode))) {
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ret = ext4_block_zero_eof(inode, oldsize, LLONG_MAX);
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if (ret)
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return ret;
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}
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handle = ext4_journal_start(inode, EXT4_HT_INODE, 3);
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if (IS_ERR(handle))
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return PTR_ERR(handle);
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old_lblk = oldsize > 0 ? (oldsize - 1) >> inode->i_blkbits : 0;
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new_lblk = newsize > 0 ? (newsize - 1) >> inode->i_blkbits : 0;
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ext4_fc_track_range(handle, inode, old_lblk, new_lblk);
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ext4_set_inode_size(inode, newsize);
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ret = ext4_mark_inode_dirty(handle, inode);
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ext4_journal_stop(handle);
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if (ret)
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return ret;
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/*
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* isize extend must be called outside an active handle due to
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* the lock ordering of transaction start and folio lock in the
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* iomap buffered I/O path (folio lock -> transaction start).
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*/
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pagecache_isize_extended(inode, oldsize, newsize);
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return 0;
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}
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static int ext4_truncate_down(struct inode *inode, loff_t oldsize,
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loff_t newsize, int *orphan)
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{
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ext4_lblk_t start_lblk;
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handle_t *handle;
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int ret;
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/* Do not change i_size. */
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if (newsize == oldsize)
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goto truncate;
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/* Shrink. */
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handle = ext4_journal_start(inode, EXT4_HT_INODE, 3);
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if (IS_ERR(handle))
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return PTR_ERR(handle);
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if (ext4_handle_valid(handle)) {
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ret = ext4_orphan_add(handle, inode);
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*orphan = 1;
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if (ret) {
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ext4_journal_stop(handle);
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return ret;
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}
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}
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start_lblk = newsize > 0 ? (newsize - 1) >> inode->i_blkbits : 0;
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ext4_fc_track_range(handle, inode, start_lblk, EXT_MAX_BLOCKS - 1);
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ext4_set_inode_size(inode, newsize);
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ret = ext4_mark_inode_dirty(handle, inode);
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ext4_journal_stop(handle);
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if (ret)
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return ret;
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if (ext4_should_journal_data(inode))
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ext4_wait_for_tail_page_commit(inode);
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truncate:
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/*
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* Truncate pagecache after we've waited for commit in data=journal
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* mode to make pages freeable. Call ext4_truncate() even if
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* i_size didn't change to truncate possible preallocated blocks.
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*/
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truncate_pagecache(inode, newsize);
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return ext4_truncate(inode);
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}
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/*
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* ext4_setattr()
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*
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@ -6078,7 +6184,6 @@ int ext4_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
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}
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if (attr->ia_valid & ATTR_SIZE) {
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handle_t *handle;
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loff_t oldsize = inode->i_size;
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int shrink = (attr->ia_size < inode->i_size);
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@ -6130,94 +6235,14 @@ int ext4_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
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goto err_out;
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}
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if (attr->ia_size != inode->i_size) {
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/* attach jbd2 jinode for EOF folio tail zeroing */
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if (attr->ia_size & (inode->i_sb->s_blocksize - 1) ||
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oldsize & (inode->i_sb->s_blocksize - 1)) {
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error = ext4_inode_attach_jinode(inode);
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if (error)
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goto out_mmap_sem;
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}
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/*
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* Update c/mtime and tail zero the EOF folio on
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* truncate up. ext4_truncate() handles the shrink case
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* below.
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*/
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if (!shrink) {
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inode_set_mtime_to_ts(inode,
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inode_set_ctime_current(inode));
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if (oldsize & (inode->i_sb->s_blocksize - 1)) {
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error = ext4_block_zero_eof(inode,
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oldsize, LLONG_MAX);
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if (error)
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goto out_mmap_sem;
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}
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}
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handle = ext4_journal_start(inode, EXT4_HT_INODE, 3);
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if (IS_ERR(handle)) {
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error = PTR_ERR(handle);
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goto out_mmap_sem;
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}
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if (ext4_handle_valid(handle) && shrink) {
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error = ext4_orphan_add(handle, inode);
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orphan = 1;
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if (error)
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goto out_handle;
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}
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if (shrink)
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ext4_fc_track_range(handle, inode,
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(attr->ia_size > 0 ? attr->ia_size - 1 : 0) >>
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inode->i_sb->s_blocksize_bits,
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EXT_MAX_BLOCKS - 1);
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else
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ext4_fc_track_range(
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handle, inode,
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(oldsize > 0 ? oldsize - 1 : oldsize) >>
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inode->i_sb->s_blocksize_bits,
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(attr->ia_size > 0 ? attr->ia_size - 1 : 0) >>
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inode->i_sb->s_blocksize_bits);
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/*
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* We have to update i_size under i_data_sem together
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* with i_disksize to avoid races with writeback code
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* updating disksize in mpage_map_and_submit_extent().
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*/
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down_write(&EXT4_I(inode)->i_data_sem);
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i_size_write(inode, attr->ia_size);
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EXT4_I(inode)->i_disksize = attr->ia_size;
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up_write(&EXT4_I(inode)->i_data_sem);
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error = ext4_mark_inode_dirty(handle, inode);
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out_handle:
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ext4_journal_stop(handle);
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if (error)
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goto out_mmap_sem;
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if (!shrink) {
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pagecache_isize_extended(inode, oldsize,
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inode->i_size);
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} else if (ext4_should_journal_data(inode)) {
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ext4_wait_for_tail_page_commit(inode);
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}
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if (attr->ia_size > oldsize)
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error = ext4_truncate_up(inode, oldsize, attr->ia_size);
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else {
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/* Shrink or do not change i_size. */
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error = ext4_truncate_down(inode, oldsize,
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attr->ia_size, &orphan);
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}
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/*
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* Truncate pagecache after we've waited for commit
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* in data=journal mode to make pages freeable.
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*/
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truncate_pagecache(inode, inode->i_size);
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/*
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* Call ext4_truncate() even if i_size didn't change to
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* truncate possible preallocated blocks.
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*/
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if (attr->ia_size <= oldsize) {
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rc = ext4_truncate(inode);
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if (rc)
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error = rc;
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}
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out_mmap_sem:
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filemap_invalidate_unlock(inode->i_mapping);
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}
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