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zonefs: Fix O_APPEND async write handling

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zonefs updates the size of a sequential zone file inode only on
completion of direct writes. When executing asynchronous append writes
(with a file open with O_APPEND or using RWF_APPEND), the use of the
current inode size in generic_write_checks() to set an iocb offset thus
leads to unaligned write if an application issues an append write
operation with another write already being executed.

Fix this problem by introducing zonefs_write_checks() as a modified
version of generic_write_checks() using the file inode wp_offset for an
append write iocb offset. Also introduce zonefs_write_check_limits() to
replace generic_write_check_limits() call. This zonefs special helper
makes sure that the maximum file limit used is the maximum size of the
file being accessed.

Since zonefs_write_checks() already truncates the iov_iter, the calls
to iov_iter_truncate() in zonefs_file_dio_write() and
zonefs_file_buffered_write() are removed.

Fixes: 8dcc1a9d90 ("fs: New zonefs file system")
Cc: <stable@vger.kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
This commit is contained in:
Damien Le Moal 2021-03-10 15:20:28 +09:00
parent 1601ea068b
commit ebfd68cd0c
1 changed files with 68 additions and 10 deletions
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78
fs/zonefs/super.c
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@ -743,6 +743,68 @@ out_release:
return ret;
}
/*
* Do not exceed the LFS limits nor the file zone size. If pos is under the
* limit it becomes a short access. If it exceeds the limit, return -EFBIG.
*/
static loff_t zonefs_write_check_limits(struct file *file, loff_t pos,
loff_t count)
{
struct inode *inode = file_inode(file);
struct zonefs_inode_info *zi = ZONEFS_I(inode);
loff_t limit = rlimit(RLIMIT_FSIZE);
loff_t max_size = zi->i_max_size;
if (limit != RLIM_INFINITY) {
if (pos >= limit) {
send_sig(SIGXFSZ, current, 0);
return -EFBIG;
}
count = min(count, limit - pos);
}
if (!(file->f_flags & O_LARGEFILE))
max_size = min_t(loff_t, MAX_NON_LFS, max_size);
if (unlikely(pos >= max_size))
return -EFBIG;
return min(count, max_size - pos);
}
static ssize_t zonefs_write_checks(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file_inode(file);
struct zonefs_inode_info *zi = ZONEFS_I(inode);
loff_t count;
if (IS_SWAPFILE(inode))
return -ETXTBSY;
if (!iov_iter_count(from))
return 0;
if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
return -EINVAL;
if (iocb->ki_flags & IOCB_APPEND) {
if (zi->i_ztype != ZONEFS_ZTYPE_SEQ)
return -EINVAL;
mutex_lock(&zi->i_truncate_mutex);
iocb->ki_pos = zi->i_wpoffset;
mutex_unlock(&zi->i_truncate_mutex);
}
count = zonefs_write_check_limits(file, iocb->ki_pos,
iov_iter_count(from));
if (count < 0)
return count;
iov_iter_truncate(from, count);
return iov_iter_count(from);
}
/*
* Handle direct writes. For sequential zone files, this is the only possible
* write path. For these files, check that the user is issuing writes
@ -760,8 +822,7 @@ static ssize_t zonefs_file_dio_write(struct kiocb *iocb, struct iov_iter *from)
struct super_block *sb = inode->i_sb;
bool sync = is_sync_kiocb(iocb);
bool append = false;
size_t count;
ssize_t ret;
ssize_t ret, count;
/*
* For async direct IOs to sequential zone files, refuse IOCB_NOWAIT
@ -779,12 +840,11 @@ static ssize_t zonefs_file_dio_write(struct kiocb *iocb, struct iov_iter *from)
inode_lock(inode);
}
ret = generic_write_checks(iocb, from);
if (ret <= 0)
count = zonefs_write_checks(iocb, from);
if (count <= 0) {
ret = count;
goto inode_unlock;
iov_iter_truncate(from, zi->i_max_size - iocb->ki_pos);
count = iov_iter_count(from);
}
if ((iocb->ki_pos | count) & (sb->s_blocksize - 1)) {
ret = -EINVAL;
@ -844,12 +904,10 @@ static ssize_t zonefs_file_buffered_write(struct kiocb *iocb,
inode_lock(inode);
}
ret = generic_write_checks(iocb, from);
ret = zonefs_write_checks(iocb, from);
if (ret <= 0)
goto inode_unlock;
iov_iter_truncate(from, zi->i_max_size - iocb->ki_pos);
ret = iomap_file_buffered_write(iocb, from, &zonefs_iomap_ops);
if (ret > 0)
iocb->ki_pos += ret;