Ext4 provides the feature of storing data inline and automatically converts it to extent data when appropriate. However, files stored as extents cannot be converted back to inline data after truncation, even if the file size allows for inline data storage. This patch set implements the feature to store large truncated files as inline data when suitable, improving disk utilization. Patches 1-3 include some cleanups and fixes. Patches 4-6 refactor the functions responsible for writing inline data, consolidating their logic for better code organization. Patch 7 implements the feature of storing truncated files as inline data on the next write operation. Below is a comparison of results before and after applying the patch set. Before: root@q:linux# dd if=/dev/urandom bs=1M count=10 of=/mnt/ext4/test 10+0 records in 10+0 records out 10485760 bytes (10 MB, 10 MiB) copied, 0.0770325 s, 136 MB/s root@q:linux# filefrag -v /mnt/ext4/test Filesystem type is: ef53 File size of /mnt/ext4/test is 10485760 (2560 blocks of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 2559: 0.. 0: 0: last,unknown_loc,delalloc,eof /mnt/ext4/test: 1 extent found root@q:linux# echo a > /mnt/ext4/test root@q:linux# filefrag -v /mnt/ext4/test Filesystem type is: ef53 File size of /mnt/ext4/test is 2 (1 block of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 0: 34304.. 34304: 1: last,eof /mnt/ext4/test: 1 extent found After: root@q:linux# dd if=/dev/urandom bs=1M count=10 of=/mnt/ext4/test 10+0 records in 10+0 records out 10485760 bytes (10 MB, 10 MiB) copied, 0.0883107 s, 119 MB/s root@q:linux# filefrag -v /mnt/ext4/test Filesystem type is: ef53 File size of /mnt/ext4/test is 10485760 (2560 blocks of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 2559: 38912.. 41471: 2560: last,unknown_loc,delalloc,eof /mnt/ext4/test: 1 extent found root@q:linux# echo a > /mnt/ext4/test root@q:linux# filefrag -v /mnt/ext4/test Filesystem type is: ef53 Filesystem cylinder groups approximately 78 File size of /mnt/ext4/test is 2 (1 block of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 1: 4340520.. 4340521: 2: last,not_aligned,inline,eof /mnt/ext4/test: 1 extent found Using filefrag, we can see that after applying this patch, large truncated files also utilize the inline data feature. This patch set has been tested with xfstests' check -g and has not introduced any additional failures. Julian Sun (7): ext4: Modify ei->i_flags before calling ext4_mark_iloc_dirty() ext4: Remove a redundant return statement ext4: Don't set EXT4_STATE_MAY_INLINE_DATA for ea inodes ext4: Introduce a new helper function ext4_generic_write_inline_data() ext4: Refactor out ext4_da_write_inline_data_begin() ext4: Refactor out ext4_try_to_write_inline_data() ext4: Store truncated large files as inline data. fs/ext4/extents_status.c | 1 - fs/ext4/ialloc.c | 2 +- fs/ext4/inline.c | 205 ++++++++++++++++----------------------- fs/ext4/inode.c | 5 + 4 files changed, 91 insertions(+), 122 deletions(-) -- 2.39.5
