Commit 96391e2bae0f8882b6f44809202a68be66e91dce
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86093aaff5
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exofs: Error recovery if object is missing from storage
If an object is referenced by a directory but does not exist on a target, it is a very serious corruption that means: 1. Either a power failure with very slim chance of it happening. Because the directory update is always submitted much after object creation, but if a directory is written to one device and the object creation to another it might theoretically happen. 2. It only ever happened to me while developing with BUGs causing file corruption. Crashes could also cause it but they are more like case 1. In any way the object does not exist, so data is surely lost. If there is a mix-up in the obj-id or data-map, then lost objects can be salvaged by off-line fsck. The only recoverable information is the directory name. By letting it appear as a regular empty file, with date==0 (1970 Jan 1st) ownership to root, we enable recovery of the only useful information. And also enable deletion or over-write. I can see how this can hurt. Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Showing 1 changed file with 11 additions and 1 deletions Side-by-side Diff
fs/exofs/inode.c
| ... | ... | @@ -903,8 +903,18 @@ |
| 903 | 903 | ios->in_attr_len = ARRAY_SIZE(attrs); |
| 904 | 904 | |
| 905 | 905 | ret = exofs_sbi_read(ios); |
| 906 | - if (ret) | |
| 906 | + if (unlikely(ret)) { | |
| 907 | + EXOFS_ERR("object(0x%llx) corrupted, return empty file=>%d\n", | |
| 908 | + _LLU(ios->obj.id), ret); | |
| 909 | + memset(inode, 0, sizeof(*inode)); | |
| 910 | + inode->i_mode = 0040000 | (0777 & ~022); | |
| 911 | + /* If object is lost on target we might as well enable it's | |
| 912 | + * delete. | |
| 913 | + */ | |
| 914 | + if ((ret == -ENOENT) || (ret == -EINVAL)) | |
| 915 | + ret = 0; | |
| 907 | 916 | goto out; |
| 917 | + } | |
| 908 | 918 | |
| 909 | 919 | ret = extract_attr_from_ios(ios, &attrs[0]); |
| 910 | 920 | if (ret) { |