mirror of https://github.com/acidanthera/audk.git
a131839a3d
This patch improves dirty bit checking in FAT and coalesces multiple writes to adjacent blocks into a single write. For good read performance, the Fat code caches 64KB lines from the file system. Any update to the data will force 64KB writes. Writing the full 64KB causes collateral blocks (i.e. blocks belonging to other files) to be written. This is inefficient to write blocks that are not dirty, the FAT driver should only be writing blocks that have actually been updated through its cache. This also resolves an issue with existing bootloaders which have ways to update files outside of the FAT code and the collateral write can corrupt those files. One such file is the Windows BCD that gets updated outside of the FAT code and has been seen to be corrupted by the collateral writes, causing the OS to fail to boot. This fix keeps track of physical disk block (LBA) size and will only mark LBA size zones of the 64KB cache line that are written to. When the file is closed and the cached data is written, only the dirty LBAs are written, which avoids the collateral write and therefore the corruption. In addition, adjacent LBAs will be coalesced into one write for performance considerations. Signed-off-by: Oliver Smith-Denny <osde@linux.microsoft.com> |
||
|---|---|---|
| .. | ||
| EnhancedFatDxe | ||
| FatPei | ||
| FatPkg.ci.yaml | ||
| FatPkg.dec | ||
| FatPkg.dsc | ||
| FatPkg.uni | ||
| FatPkgExtra.uni | ||