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KallistiOS
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KallistiOS
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VFS interface for an ext2 filesystem. More...
Go to the source code of this file.
Macros | |
| #define | FS_EXT2_MOUNT_READONLY 0x00000000 |
| Mount read-only. More... | |
| #define | FS_EXT2_MOUNT_READWRITE 0x00000001 |
| Mount read-write. More... | |
Functions | |
| int | fs_ext2_init (void) |
| Initialize fs_ext2. More... | |
| int | fs_ext2_shutdown (void) |
| Shut down fs_ext2. More... | |
| int | fs_ext2_mount (const char *mp, kos_blockdev_t *dev, uint32_t flags) |
| Mount an ext2 filesystem in the VFS. More... | |
| int | fs_ext2_unmount (const char *mp) |
| Unmount an ext2 filesystem from the VFS. More... | |
| int | fs_ext2_sync (const char *mp) |
| Sync an ext2 filesystem, flushing all pending writes to the block device. More... | |
VFS interface for an ext2 filesystem.
This file defines the public interface to add support for the Second Extended Filesystem (ext2) to KOS' VFS. ext2 is one of the many filesystems that is natively supported by Linux, and was the main filesystem used by most Linux installations pretty much until the creation of the ext3 filesystem.
The KOS ext2 driver was designed with two purposes. First of all, this fs was added to provide a filesystem for use on SD cards used with the Dreamcast SD adapter. ext2 was chosen for this purpose for a bunch of reasons, but probably the biggest one was the non-patent-encumbered nature of ext2 and the availability of programs/drivers to read ext2 on most major OSes available for PCs today. The second purpose of this filesystem driver is to provide an alternative for fs_romdisk when swapping out disk images at runtime. Basically, if a disk image is useful to you, but cacheing it fully in memory is not important, then you could rig up a relatively simple interface with this filesystem driver.
Note that there is a lower-level interface sitting underneath of this layer. This lower-level interface (simply called ext2fs) should not generally be used by any normal applications. As of this point, it is completely non thread-safe and the fs_ext2 layer takes extreme care to overcome those issues with the lower-level interface. Over time, I may fix the thread- safety issues in ext2fs, but that is not particularly high on my priority list at the moment. There shouldn't really be a reason to work directly with the ext2fs layer anyway, as this layer should give you everything you need by interfacing with the VFS in the normal fashion.
There's one final note that I should make. Everything in fs_ext2 and ext2fs is licensed under the same license as the rest of KOS. None of it was derived from GPLed sources. Pretty much all of what's in ext2fs was written based on the documentation at http://www.nongnu.org/ext2-doc/ .
| int fs_ext2_init | ( | void | ) |
Initialize fs_ext2.
This function initializes fs_ext2, preparing various internal structures for use.
| 0 | On success. No error conditions currently defined. |
| int fs_ext2_mount | ( | const char * | mp, |
| kos_blockdev_t * | dev, | ||
| uint32_t | flags | ||
| ) |
Mount an ext2 filesystem in the VFS.
This function mounts an ext2 filesystem to the specified mount point on the VFS. This function will detect whether or not an ext2 filesystem exists on the given block device and mount it only if there is actually an ext2 filesystem.
| mp | The path to mount the filesystem at. |
| dev | The block device containing the filesystem. |
| flags | Mount flags. Bitwise OR of values from ext2_mount_flags |
| 0 | On success. |
| -1 | On error. |
| int fs_ext2_shutdown | ( | void | ) |
Shut down fs_ext2.
This function shuts down fs_ext2, basically undoing what fs_ext2_init() did.
| 0 | On success. No error conditions currently defined. |
| int fs_ext2_sync | ( | const char * | mp | ) |
Sync an ext2 filesystem, flushing all pending writes to the block device.
This function completes all pending writes on the filesystem, making sure all data and metadata are in a consistent state on the block device. As both inode and block writes are normally postponed until they are either evicted from the cache or the filesystem is unmounted, doing this periodically may be a good idea if there is a chance that the filesystem will not be unmounted cleanly.
| mp | The mount point of the filesystem to be synced. |
| 0 | On success. |
| -1 | On error. |
| int fs_ext2_unmount | ( | const char * | mp | ) |
Unmount an ext2 filesystem from the VFS.
This function unmoutns an ext2 filesystem that was previously mounted by the fs_ext2_mount() function.
| mp | The mount point of the filesystem to be unmounted. |
| 0 | On success. |
| -1 | On error. |
1.8.7
