nilfs2: prevent kernel bug at submit_bh_wbc()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: nilfs2: prevent kernel bug at submit_bh_wbc() Fix a bug where nilfs_get_block() returns a successful status when searching and inserting the specified block both fail inconsistently. If this inconsistent behavior is not due to a previously fixed bug, then an unexpected race is occurring, so return a temporary error -EAGAIN instead. This prevents callers such as __block_write_begin_int() from requesting a read into a buffer that is not mapped, which would cause the BUG_ON check for the BH_Mapped flag in submit_bh_wbc() to fail.

References

• https://git.kernel.org/stable/c/91e4c4595fae5e87069e44687ae879091783c183
• https://git.kernel.org/stable/c/32eaee72e96590a75445c8a6c7c1057673b47e07
• https://git.kernel.org/stable/c/f0fe7ad5aff4f0fcf988913313c497de85f1e186
• https://git.kernel.org/stable/c/ca581d237f3b8539c044205bb003de71d75d227c
• https://git.kernel.org/stable/c/192e9f9078c96be30b31c4b44d6294b24520fce5
• https://git.kernel.org/stable/c/0c8aa4cfda4e4adb15d5b6536d155eca9c9cd44c
• https://git.kernel.org/stable/c/48d443d200237782dc82e6b60663ec414ef02e39
• https://git.kernel.org/stable/c/76ffbe911e2798c7296968f5fd72f7bf67207a8d
• https://git.kernel.org/stable/c/269cdf353b5bdd15f1a079671b0f889113865f20