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| author | Chandan Rajendra | 2016-01-21 11:26:03 +0100 |
|---|---|---|
| committer | David Sterba | 2016-02-01 19:24:29 +0100 |
| commit | 27772b68f6994f0011690899c31717b7cbec51c9 (patch) | |
| tree | 51c06f3d06a72082de3e63e6c7c2a9a710d4369b /fs/btrfs/file.c | |
| parent | Btrfs: Fix block size returned to user space (diff) | |
| download | kernel-qcow2-linux-27772b68f6994f0011690899c31717b7cbec51c9.tar.gz kernel-qcow2-linux-27772b68f6994f0011690899c31717b7cbec51c9.tar.xz kernel-qcow2-linux-27772b68f6994f0011690899c31717b7cbec51c9.zip | |
Btrfs: Clean pte corresponding to page straddling i_size
When extending a file by either "truncate up" or by writing beyond i_size, the
page which had i_size needs to be marked "read only" so that future writes to
the page via mmap interface causes btrfs_page_mkwrite() to be invoked. If not,
a write performed after extending the file via the mmap interface will find
the page to be writaeable and continue writing to the page without invoking
btrfs_page_mkwrite() i.e. we end up writing to a file without reserving disk
space.
Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/file.c')
| -rw-r--r-- | fs/btrfs/file.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 58bb29788f5f..953f0ad17802 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1778,6 +1778,8 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, ssize_t err; loff_t pos; size_t count; + loff_t oldsize; + int clean_page = 0; mutex_lock(&inode->i_mutex); err = generic_write_checks(iocb, from); @@ -1816,14 +1818,17 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, pos = iocb->ki_pos; count = iov_iter_count(from); start_pos = round_down(pos, root->sectorsize); - if (start_pos > i_size_read(inode)) { + oldsize = i_size_read(inode); + if (start_pos > oldsize) { /* Expand hole size to cover write data, preventing empty gap */ end_pos = round_up(pos + count, root->sectorsize); - err = btrfs_cont_expand(inode, i_size_read(inode), end_pos); + err = btrfs_cont_expand(inode, oldsize, end_pos); if (err) { mutex_unlock(&inode->i_mutex); goto out; } + if (start_pos > round_up(oldsize, root->sectorsize)) + clean_page = 1; } if (sync) @@ -1835,6 +1840,9 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, num_written = __btrfs_buffered_write(file, from, pos); if (num_written > 0) iocb->ki_pos = pos + num_written; + if (clean_page) + pagecache_isize_extended(inode, oldsize, + i_size_read(inode)); } mutex_unlock(&inode->i_mutex); |