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erofs: restrict pcluster size limitations

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Error out if {en,de}encoded size of a pcluster is unsupported:
  Maximum supported encoded size (of a pcluster):  1 MiB
  Maximum supported decoded size (of a pcluster): 12 MiB

Users can still choose to use supported large configurations (e.g.,
for archival purposes), but there may be performance penalties in
low-memory scenarios compared to smaller pclusters.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240912074156.2925394-1-hsiangkao@linux.alibaba.com
This commit is contained in:
Gao Xiang 2024-09-12 15:41:56 +08:00
parent 79f504a2cd
commit 7c3ca1838a
2 changed files with 24 additions and 23 deletions
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5
fs/erofs/erofs_fs.h
View File

@ -288,9 +288,12 @@ struct erofs_dirent {
#define EROFS_NAME_LEN 255
/* maximum supported size of a physical compression cluster */
/* maximum supported encoded size of a physical compressed cluster */
#define Z_EROFS_PCLUSTER_MAX_SIZE (1024 * 1024)
/* maximum supported decoded size of a physical compressed cluster */
#define Z_EROFS_PCLUSTER_MAX_DSIZE (12 * 1024 * 1024)
/* available compression algorithm types (for h_algorithmtype) */
enum {
Z_EROFS_COMPRESSION_LZ4 = 0,

42
fs/erofs/zmap.c
View File

@ -687,32 +687,30 @@ int z_erofs_map_blocks_iter(struct inode *inode, struct erofs_map_blocks *map,
int err = 0;
trace_erofs_map_blocks_enter(inode, map, flags);
/* when trying to read beyond EOF, leave it unmapped */
if (map->m_la >= inode->i_size) {
if (map->m_la >= inode->i_size) { /* post-EOF unmapped extent */
map->m_llen = map->m_la + 1 - inode->i_size;
map->m_la = inode->i_size;
map->m_flags = 0;
goto out;
} else {
err = z_erofs_fill_inode_lazy(inode);
if (!err) {
if ((vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER) &&
!vi->z_tailextent_headlcn) {
map->m_la = 0;
map->m_llen = inode->i_size;
map->m_flags = EROFS_MAP_MAPPED |
EROFS_MAP_FULL_MAPPED | EROFS_MAP_FRAGMENT;
} else {
err = z_erofs_do_map_blocks(inode, map, flags);
}
}
if (!err && (map->m_flags & EROFS_MAP_ENCODED) &&
unlikely(map->m_plen > Z_EROFS_PCLUSTER_MAX_SIZE ||
map->m_llen > Z_EROFS_PCLUSTER_MAX_DSIZE))
err = -EOPNOTSUPP;
if (err)
map->m_llen = 0;
}
err = z_erofs_fill_inode_lazy(inode);
if (err)
goto out;
if ((vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER) &&
!vi->z_tailextent_headlcn) {
map->m_la = 0;
map->m_llen = inode->i_size;
map->m_flags = EROFS_MAP_MAPPED | EROFS_MAP_FULL_MAPPED |
EROFS_MAP_FRAGMENT;
goto out;
}
err = z_erofs_do_map_blocks(inode, map, flags);
out:
if (err)
map->m_llen = 0;
trace_erofs_map_blocks_exit(inode, map, flags, err);
return err;
}