diff options
| author | Joanne Koong <joannelkoong@gmail.com> | 2025-11-11 11:36:51 -0800 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2025-11-12 10:50:31 +0100 |
| commit | 9d875e0eef8ec15b6b1da0cb9a0f8ed13efee89e (patch) | |
| tree | 495218333e496345cab1c340223e87f1c221ea8f | |
| parent | a0f1cabe294c914ef58a414dce0de5c46a767bb5 (diff) | |
iomap: account for unaligned end offsets when truncating read range
The end position to start truncating from may be at an offset into a
block, which under the current logic would result in overtruncation.
Adjust the calculation to account for unaligned end offsets.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://patch.msgid.link/20251111193658.3495942-3-joannelkoong@gmail.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
| -rw-r--r-- | fs/iomap/buffered-io.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 7dcb8bbc9484..0eb439b523b1 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -219,6 +219,22 @@ static void ifs_free(struct folio *folio) } /* + * Calculate how many bytes to truncate based off the number of blocks to + * truncate and the end position to start truncating from. + */ +static size_t iomap_bytes_to_truncate(loff_t end_pos, unsigned block_bits, + unsigned blocks_truncated) +{ + unsigned block_size = 1 << block_bits; + unsigned block_offset = end_pos & (block_size - 1); + + if (!block_offset) + return blocks_truncated << block_bits; + + return ((blocks_truncated - 1) << block_bits) + block_offset; +} + +/* * Calculate the range inside the folio that we actually need to read. */ static void iomap_adjust_read_range(struct inode *inode, struct folio *folio, @@ -263,7 +279,8 @@ static void iomap_adjust_read_range(struct inode *inode, struct folio *folio, /* truncate len if we find any trailing uptodate block(s) */ while (++i <= last) { if (ifs_block_is_uptodate(ifs, i)) { - plen -= (last - i + 1) * block_size; + plen -= iomap_bytes_to_truncate(*pos + plen, + block_bits, last - i + 1); last = i - 1; break; } @@ -279,7 +296,8 @@ static void iomap_adjust_read_range(struct inode *inode, struct folio *folio, unsigned end = offset_in_folio(folio, isize - 1) >> block_bits; if (first <= end && last > end) - plen -= (last - end) * block_size; + plen -= iomap_bytes_to_truncate(*pos + plen, block_bits, + last - end); } *offp = poff; |